Electron and Optical Microscopy

Electron and Optical Microscopy L. Ben-Dor Departments of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel Parti: Electron Microscopy CONTENTS 1 2 3 4 5 6'

Introduction Unhydrated Clinker and Clinker Minerals Silicate Hydrates Calcium Aluminate Hydrates Cement, Mortar and Concrete Hydration Slag Cement, Blast-furnace Cement, Polymer-impregnated Concrete and Fibre-reinforced Cement 7 Fly-ash, Pozzolana and Inorganic Cements 8 Alkali Silica/aggregate Cements 9 Plasters Dedication Acknowledgement References 1 INTRODUCTION

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Midgley [1] discussed the formation and phase composition of Portland cement clinker and included electron microscopy in the methods of qualitative examination. Plates of thin section of clinker showing various cement minerals are presented. Grudemo [2], in the same treatise, reviewed electron microscopy of cement pastes from the early studies of Eitel and co-workers (1939-42) and up to 1962. Micrographic plates are shown of cement suspension and paste, and various hydrated cement minerals. Effects of admixtures, temperature and aggregate materials on microstructure were also discussed. Various other micrographs of cement minerals, natural and synthetic, appear in Vol. 2 of the same treatise [3J. Chatterji [4] cited several precautions to be taken in the use of SEM techniques for the study of cements. Problems could arise in two main areas: the nature of the instrument and the specimen preparation. Fracture in tension was suggested to give the least distortions, and carbon coatings were found to be advantageous in comparison to metal ones.

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The SEM produced in England and Japan in the late sixties gave a further push to cement research. Due to the machine's deep focal length it was found useful for the observation of the structure of fibres, powders and porous bodies. Within ten years [5] the SEM was being used to examine fracture, an area once exclusively restricted to optical microscope and more and more fractographs are appearing. 2

UNHYDRATED CLINKER AND CLINKER MINERALS

Microstructure [6] of clinkers prepared by the dry method were compared with those by the wet method, and morphological characteristics [7] of undisturbed clinker minerals were described. When EDXA is fitted to SEM installations, the data permit the accumulation of at least semiquantitative information on structure. This was indicated by Diamond [8] and by Hantshe [9]. However, a warning [10] was sounded in using the joint technique; serious errors could arise in semi-quantitative determinations of composition, especially for rough surfaces. Incidence and take-off angles are important factors and so are variations in local areas. Half a decade later [11], scientists are still worried with the undesirable artefacts that can be introduced by the use of EDXA coupled to the SEM, and the optimum conditions for its use are being studied. This technique had been used in the study of Portland cement clinkers under dry and humid conditions (storage problems) and for identifying various minerals [12] (Figs. 1 and 2), and for examining industrial clinkers [13]. Silicon was used as primary standard in quantitative EDXA [14] and the analysis of Ca, Si, Al and Fe in individual grains [15] enabled characterization of the. main cement minerals. Further studies made it possible to differentiate between silicates and aluminates [16] and to investigate the composition of belite grains in commercial clinkers [17-18]. This joint technique was also used to study ettringite [19]. Acetic acid vapour was found to be a suitable etchant for clinker prior to microscopic observation [20]. Various reviews [21-24] deal with microstructure of both anhydrous clinker and hydrated cement. For the study of minor constituents in clinkers and impurities, microscopy was used with electron diffraction [25] and with EPMA. The latter was used [26-29 ] to study minor elements incorporated in the four major phases and to give ranges of composition of both major and minor elements in alites, belites and interstitial material found in commercial clinkers. SEM was used to study fracture of C3S and C2S grains [30], The effect of heating to 1400 C followed by slow cooling [31] and that of fineness of grinding [32] on clinker microstructure was also revealed by microscopy. Besides mineral composition [33], sampling method as affecting the accuracy of the analytical results was determined [34], Microscopic techniques were shown to offer a wide range of control of parameters essential in cement manufacture [35]. The interplay between clinker microstructure and phase distribution and hydraulic properties was investigated [36]. Concerning reliability of quantitative estimations [37], it was stated that point counting was much superior to grid counting.

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TEM was used [38] to study defects in clinker phases and to differentiate alite and bellte polymorphic modifications. FeO in raw mixes [39] reduced C3S content in clinker and affected microstructure. C3S phase change rhombohedral - monoclinic (M3) at 1000 C was characterized microscopically [40]. Lower temperature phases Mi and M 2 (900°C) were also identified. The high temperature M3 phase was stabilized at ambient temperature by rapid cooling and in the presence of sufficient MgO in solid solution. Reduction in MgO content produced Μχ form.

Fig. 1.

A l i t e ^ and Belite (#) χ 1600.[12 ].

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Fig. 2.

(a) Needlelike hydrates growing from interstitial phase *800. (b) Platy rosette growing on surface of fractured clinker xl600. [12].

SEM was used [41] to characterize clinkers produced from various raw materials by different processes. The composition of the raw mix and the conditions of clinkerization greatly affect the clinker microstructure, and the distribution and size of the silicate grains. It was concluded that SEM provides a unique and accurate means for evaluating and controlling inhomogeneity of the feed and product. The same author 142] examined four commercial samples by SEM and found that variation in composition of Portland clinker and grindability showed variation in microstructure. Raw mix compositions, homogeneity and burning/cooling conditions were also related to clinker microstructure [43]. Regourd [44] reviewed the crystal chemistry of Portland cement minerals and also the texture and microstructure of clinker. Electron microscopy among other means has been found very useful in the control of the burnability of clinker and predictability of the quality of cement stone. Recently [45] various silicate phases (a-, a'-, 3-C2S), stabilized by impurities, were prepared and studied also by electron microscopy. 3 SILICATE HYDRATES A brief review of the applications of SEM to silicate research was presented [46], A similar study was published more recently [47] wherein the microstructure of silicate hydration products was described.

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Ciach and co-workers [48] studied microstructural changes, with time, of hydrated C3S by SEM (and XRD). The products consisted of amorphous material, crumpled foils, fibrous particles and plates. The platy morphology occurred for C-S-H as well as for CH. Comparison was made between C3S and Portland cement paste. Daimon and co-workers [49] defined three hydrated phases in C3S paste: inner C-S-H, outer C-S-H and CH crystals. The latter two made up the outer product and seemed to contribute to the strength of the hardened paste. Nestik and co-workers [50] found that the nature of the initial crystallization of large single crystals of C3S was a function of stage-wise hydration. If the original grains were large, the growth of individual hydrosilicate fibres, during early hydration, was more intensive. Lawrence and co-workers [51-53] published a series of reports on the early hydration of C3S paste. Two distinct C-S-H morphologies had been observed: an acicular product and an inner product not resolved by the SEM. In the second study, the fracture of the hardened paste was studied and the path of fracture was found to change with age: in young pastes the fracture passed through the highly porous C-S-H gel; in more mature pastes, there was no discrimination as the matrix became more homogeneous in porosity. In the third study it was shown that some calcium salts modifed the morphology of both the gel and CH (Figs. 3 and 4). Nearly all admixtures caused reduction in the c-axis as compared to the a-axis of CH crystals until both became of comparable dimensions. Collepardi [54] produced further evidence to strengthen the above observations [51] but Lawrence and Young [56] stressed that large magnifications, above X20,000, showed no new features. In a second discussion [55] the striking similarity between micrographs of Portland cement paste and C3S paste was pointed out. . Thus additional credence was lent to the view that there is a basic similarity between the gel phase of C3S and of Portland cement. McConnell [57] showed that the hydrogel formed during the hydration of bredigite and larnite in nature was different from tobermorite. The structure of the fundamental crystalline sheets in the hydrogel was found to be complex. Tobermorite (11 Â) and hydrated magnesium silicate talc-like material were investigated by SEM and by TEM [58], The lath-like plates of tobermorite were very thick compared with the synthetic products which gave irregular flake-shaped aggregates similar to the talc-like material. The carbonization of porous concrete was studied by various techniques including SEM [59]. It was observed that no substantial change occurred in the habit of the (11 A) tobermorite crystals, even though decomposition had taken place. Hydration of silicates was studied both with addition of alkali carbonates [60] and when exposed to CO2 [61]. It was shown that SEM morphology of C-S-H under CO2 atmosphere was different from that without CO2. The calcite crystals, from the carbonated samples, were <1 nm in size and seemed to be contaminated with S1O2 or C-S-H type material; thus making it difficult to distinguish C-S-H from calcite. The inner portion of the sample consisted of fairly dense material.

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Fig. 3.

Acicular CSH gel: C3S 7 d hydration.[53 ]

Chiocchio and Collepardi [62-63] studied cement minerals after autoclaving. In the case of C3S, long fibrous crystals of C3SH1.5 were observed and rectangular block-shaped crystals of QC-C2SH. On the addition of CaCl2, fibres were found to cover the C3S granules. In contrast, after roomtemperature hydration, laminar particles of irregular shapes were formed. SEM micrographs also showed that pre-curing prior to autoclaving caused the formation of the largest amount of fibrous C3SHi,5. Other hydrated cement minerals of various compositional mixtures were also examined. It was shown that xonotlite produced after autoclaving [64] gave poor strength due to its less dense matrix compared to C-S-H gel. Alunno-Rossetti and co-workers [65] reported that C3S pastes hydrated at either 25° or 90°C gave similar fibrous morphology radiating from C3S granules. This view was not shared by Skalny [66] in a porosity study, although similarity between the results of both groups could be demonstrated [67]. In any case, a decrease in porosity was always associated with increase in hydration temperature. Another study also dealt with porosity of hydrated C3S paste viewed by SEM"[68]. Studies on the C/S ratios in C-S-H of hardened cement paste using SEM-EDXA combination were reported [69-70]. It was suggested [70] that ratios in excess of 2.3 probably represented the occurrence of higher calcium phases. This review contained a summary of the structure and properties of hardened paste.

Electron and Optical Microscopy

Fig. 4.

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C3S paste + CaC#2 0.5 d hydration; arrows show pullouts due to fracture.[53J.

Marchese [71 a,b] and Berger and co-workers [72] concentrated on fracture characteristics of hydrated C3S. The emphasis was placed on the intergranular and transcrystalline Ca(0H)2 fractures. Teoreanu and Muntean [73] studied calcium silicates - water - electrolyte systems and observed the morphology of the products as well as other properties. Transmission electron microscopy was used to observe thin films of hydrated cementiteous materials [74-76], Lawrence and co-workers [77] used TEM on thin films of hydrated C2S. Two forms of C-S-H(II) were observed: fans and fibre bundles, and also afwillite and CH morphologies (Figs. 5-6). Goto and co-workers [78] used an electron probe in suitable areas from SEM examinations for determining the chemical composition, C/S, of C-S-H. An etching technique permitted distinguishing areas of "inner product" from "outer product". Extensive electron microscopy and other methods were presented [79] for studying the crystal structure of C-S-H(II). An overview of the microstructure of cement paste, in considerable detail, was presented by Diamond [80]. A revised classification of four types of hydration products was suggested:

740 Type I Type II Type III Type IV

L. Ben-Dor Fibrous particles. Reticular network (honeycomb), undistinguishable individual particles. Small irregular grains (0.3 nm across). Inner product, packed small grains (0.1 nm in size).

Regourd and co-workers [81 ] observed the microstructure of C-S-H after 7 d hydration of C3S, revealing a uniform coverage of the grains by gel. An extensive discussion regarding the initial stages of C3S hydration [82] showed that the induction period was due to the formation, on the C3S surface, of a hydrate closely covering the anhydrous surface [cf. 81 ]. Further studies on the hydration mechanism of C3S, also using SEM had been presented Γ83-84].

Fig. 5.

TEM, C2S 3 d hydration; crumpled foils. [77].

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Fig. 6. TEM, C S 6 d hydration; fan morphology. [ 77 ] . Kalousek and co-workers [85] conducted an extensive characterization study of xonotlite. The microstructure of binders hydrothermally hardened above lOO^C was studied and described [86], In the range 50-300 C the major phases found were C-S-H, tobermorite and xonotlite. The composition of various zones of C-S-H gel produced from C3S paste was studied using an SEM equipped for EDXA [87], Collepardi and Marchese [88] observed that neat pastes of C3S produced, after hydration, laminar particles of C-S-H which changed after a few hours of hydration into curled cigar-shaped particles. However, no morphological changes were observed, with time, for pastes containing CaCl2· Berger and co-workers [89] agreed that the microstructure of C-S-H(I) is not affected by CaCl2 but that of C-S-H(II) is generally associated with accelerating admixtures such as CaCl2· Odler and Skalny [90] showed that the neat product of C3S paste took the form of cigar-shaped fibres while in the presence of CaCl2 the products had a spherulitic morphology.

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Traetteberg and co-workers [91-92] also studied the microstructural behavior of C3S pastes in presence of CaCl2. They found both foil-like C-S-H(I) and fibrous C-S-H(II). In the presence of CaCl2 the hexagonal feature of CH crystals became less distinct. However, Collepardi and co-workers [93] found no fibrous particles in all of their cements hydrated in the presence of the same admixture [cf. 88]. Ben-Dor and Perez [94] examined the influence of CaCl2, CrCl"3 and Cdl2 on the microstructure of C3S paste. Large hexagonal plates of CH were found only in pastes that showed a retardation effect on hydration. CaCl2 (accelerator) promoted the development of a gel phase with a honeycomb-like structure while Cdl2 (retarder) enhanced the formation of sponge-like C-S-H phase [cf. 91-92] (Fig. 7). Another study [95] dealt with the influence of CaCl2 on the microstructure of alite paste, and in a recent one [96], the early hydration of the same system was studied. The microstructure of pastes produced from 0-C2S with and without admixtures was studied by Young and Tong [97]. Similarity was found with the feature of C3S pastes, except that larger and better developed outer product Type I elongated particles, and large CH crystals were developed. An attempt to relate microstructure observed for C3S and 3-C2S pastes to mechanical and physical properties was reported by Lawrence and co-workers [98J. Changes in microstructure, induced by admixtures, were not found to affect mechanical strength. The microstructure of 3-year-old C3S and alite pastes was investigated by Marchese [99], and twin matching surfaces on either side of the fracture were compared. In discussing an earlier paper by Goto and co-workers [78], Marchese [100] questioned certain interpretations made by the authors in their study.of C3S paste micromorphology and phase composition. In their reply [101], the authors reiterated their belief in the utility of etching, prior to SEM examination, for the interpretation of morphological detail in hardened pastes. In a number of studies an outline of SEM results in various general applications usually including, but not limited to, C-S-H hydration products had been described [102-104], Another study concentrated on the morphology of C-S-H containing sodium originating from hydrothermal systems [105]. Polymorphic modifications of C3S were prepared by autoclaving with La2Û3 and ZnO [106]. The fractured surfaces revealed polycrystalline plates of C2SH and CH and also amorphous gel with honeycombe texture. Young and co-workers [Ί07] hydrated C3S with and without admixtures and examined the changes in the microstructure. The influence of admixtures could be predicted from their effect on the crystal growth of CH, the nucleation of which controlled the induction period cf.[94], Chromate ions [108] were found to accelerate the hydration of alite and change the morphology of the hydration products. An admixture which was found to stabilize C2S was B2O3 [109], its activity being due to differences in crystal imperfections as determined by electron microscopy (and diffraction). Dent Glasser and co-workers [110] suggested that C-S-H exists as a surface hydrate attached to the C3S particle and a precipitated hydrate including both Type I and Type II [cf. 80]. It was found that the Type depended on lime concentration of the system [111]. In low lime systems C-S-H(I) developed as flaky-crinkly, irregular crystals intermingled with twisted foils, whereas in supersaturated lime solutions C-S-H(III) formed as fibres and needle-like bundles. It was also found that alkalis influenced the composition and structure of hydration products, and that the C-S-H formed had a fibrous structure [C-S-H(III)?] [112].

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Various polymorphs of C3S gave morphologically different hydration products [113], on the other hand, different synthetic alites gave C-S-H of similar morphology [114], thus showing that hydrated pure C3S is different from hydrated synthetic alites [115]. The initial reaction in the zeolitic tuff - CaQ-^O system [116] was the dissolution of zeolite and portlandite; tobermorite was formed by heterogeneous nucleation on the' C-S-H(I) - liquid interface. Bentur and co-workers [117] studied drying shrinkage and induced microstructural changes of calcium silicate pastes. Drying and loading increased silicate polymerization. Various morphological forms of hydrated cement minerals were related to their strength developing properties [118]. The nature of various calcium silicate hydrates had been studied [119], and also the effect of tricalcium silicate hydrate crystals on the microstructure of C3S paste [120]. The effect of water and inorganic salt solutions on the microstructure of hydrated alite, C3S and Portland cement was determined [121]. Calcium hydroxide in the fresh surface was found to be unstable while, in comparison, C-S-H was more resistant towards all admixture solutions. Bentur and co-workers [122] correlated irreversible strains on loaded calcium silicate pastes with structural changes occurring within the pastes. These changes were interpreted in terms of microstructural models of the hydrated pastes. This paper was discussed by Chatterji [123] and a reply by the former authors was presented [124]. In a further study [125], strains of calcium silicate pastes containing CaCl2 or cured at 65 C were measured and correlated with evidence of structural changes. Previously observed negative „effect of phosphate on the hydration of Portland cement was substantiated by results obtained from studies of the system C3S:P2Û5 [126]. C3S in presence of sugars and sugar acids [127], hydrated' to give C-S-H gel which was found to be flaky and not acicular. In low porosity C3S pastes the hydration products were semicrystalline, whereas in high porosity pastes the hydrates appeared as tubular masses joined to partly-hydrated grains [128]. Reactivity and stabilization of silicate hydrates on carbonation had been studied [129-130]. Photomicrographs showed that the morphology of the precarbonated material was retained. Another study revealed [131] that aragonite was the principal carbonate formed and C-S-H gel formation was minimal. The aragonite obtained had a block habit when formed from C2S, and an orthorhombic lath habit from C3S. Recently high-resolution SEM with and without ESCA and high-resolution scanning TEM (STEM) had been used to explore the surface hydration of silicates [132-135] (Figs. 8-10). The surface texture of C3S was studied during the first 3 hours of hydration. Only honeycomb Type II C-S-H was observed and at no time was acicular Type I C-S-H morphology found. The surface morphology of early hydration 3-C2S was also studied on immediate contact with water. The hydration products were formed at localized spots and were mostly short rod-like particles found on or near grain boundaries. These results were different from those observed with C 3 S. The effect of gypsum on the early stages of hydration of C3S caused the beginning of honeycomb morphology and large CH crystals. Later there was transformation of the thin sheets that form honeycomb C-S-H^into parallel fibre bundles. Another STEM study [136] using a very large enlargement (X80,000) showed the equant grains of Type III C-S-H cf.[77]. Both thin foils of cement paste and hydrated C3S were examined. It was shown that in young paste, inter-particle

Electron and Optical Microscopy

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fracture took place through the porous C-S-H gel and around the crystalline CH. As the paste matured, the extent of transparticle fracture increased, with the crack propagating through both the C-S-H and CH regions along a much straighter path. Taylor [137] discussed silicate phases in cement hydration reactions, and concentrated on results of analytical electron microscopy. Various studies [138-140, cf. 69,70,78,87] discussed C/S ratios in C3S pastes and in cement pastes, and a difference in composition between inner and output products. In a more recent study [141] it was shown that the overall range of C/S ratios of C-S-H particles from C3S pastes was 1.21-1.96. Most of the variation was considered to represent real differences in composition between individual particles. No significant correlations with curing time, degree of hydration or morphological type of C-S-H were found. The microstructure of hydrated C3S in the absence and presence of heavy metal hydroxides was studied [142]. Hydration characteristics were followed by microscopic observation (and XRD) for C3S, C2S and other cement minerals alone and in mixed systems 1143-144]. Combined silicate hydrate crystals were broader and shorter than those of either silicate alone.

Fig. 8.

High-resolution SEM anhydrous C3S - smooth surface.

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Fig. 9.

High-resolution SEM 10 min hydrated C3S leached surface *25,000. [ 132 ].

Fig. 10. High-resolution SEM 180 min hydrated C3S - Type II or honeycomb CSH *25,000. [132],

Electron and Optical Microscopy 4

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CALCIUM ALUMINATE HYDRATES

The formation of ettringite by various reactions in the system CA-CS-CH was studied [145], Acicular crystals were observed where a mixture of C3A with 3 moles of gypsum was hydrated. Ciach and Swenson studied in detail [146] the morphology and microstructure of hydrated calcium aluminate, calcium silicates, gypsum and Portland cement with and without organic admixtures. The specific influence of the admixtures on the microstructure was small and the morphological changes that occurred in the cement paste were similar to those in the mixture of cement minerals (Figs. 11-12). Gupta and co-workers [147] studied the effect of lime, calcium salts and NaOH on the hydration of C3A by TEM and SEM (and XRD). During neat hydration comparatively large, thick crystals of hexagonal CAHIQ were formed, but in the presence of CH the products were thin, small crystals of C H AH X . These crystals formed an impervious coating to water, on the C3A grains, thus retarding the hydration. There was evidence [148] that 80 C considerably accelerated the 20 C hydration reaction of calcium aluminate. The low-temperature hydrated material showed cracks but these were not observed in the samples cured at 80 C. Many studies were devoted to the changes accompanying the conversion of hexagonal CAHiQ to cubic C3AH5 [149], Evidence was found [150] that at low-temperature (20°C) hydration of C3A, the hexagonal morphology was prominent while at high temperature (80°C) the cubic phase resulted. Strength was attributed to the formation of a closely welded network of the cubic phase. Triethanolamine [151] accelerated the conversion as also the formation of ettringite in the C3A-CS-H20 system. Ettringite needles predominated in all samples for early age, and, with time, the morphology became more platy due to the formation of hexagonal aluminate hydrate. Salicylic acid acted as a retarder for C3A hydration [152]. Agglomerations of small (0.3 nm) equiaxed particles were precipitated from concentrated solutions of the acid, and were accompanied by peculiar hexagonal prismatic crystallites with rounded edges of CH. In more dilute solutions, distorted hexagonal plates of C^AH^-type compounds were also formed. The hydration of C3A was studied in a mixed cement minerals-water system [153]. Crystal hydrates were relatively unstable and most products formed mainly as micro- and submicrocrystals. Cottin [154] studied the hydration of high alumina cement. At 12°C, CAHIQ was observed and at 30 C, C 2 AH Ö . The former developed from seeds during the dormant period which later produced pencil-like crystals. Another study on a high alumina cement involved curing at 18CC and 50°C [155]. Below 50°C pastes contained largely CAH^o and showed some healed cracking; above 50 C the pastes contained C3AH6 with gibbsite (γ-ΑΗ3).

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Fig. 11.

C3A 3d hydration. Cubic hydrogarnet crystals covered by small hexagonal and other hydration products. [146 ].

Carbonization of C3AH6 gave C3AH11 which decomposed into A1(0H)3 and vaterite and later transformed into calcite. The microstructure of the transformation was studied [156]. The hydration of calcium sulphoaluminate was also studied in the above report as well as by another group [157], Hydrated calcium aluminate reacted with carbonate ions (dissolution of CaCC^) to produce calcium hydrocarboaluminate [158], It was shown that the reaction was limited to the interfacial zone and depended on w/c ratio. The mineral CxiA7.CaF2 is native to Japan and thus was subject to studies in that country 1159-160]. Cements of low C3A content were found to produce pastes of higher frost resistance 1161-162]. Microstructure, porosity and specific surface of high alumina cements were obtained by electron microscopy [163], It was suggested that differences in microstructure could be caused by different rates of transformation reactions.

Electron and Optical Microscopy

Fig. 12.

C3A with gypsum (and calcium lignosulphonate) 14 d hydration. Short ettringite rods between small rounded low-sulphate CAH plates. [146 ].

Fig. 13.

Gypsum in C3A solution 1 hr. on surface of gypsum.[168 ].

Ettringite crystals

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Traetteberg and Sereda [164] observed morphological changes in C3A and c A 3 "gyPsuin pastes after addition of CaCl2. It: w a s also found [165] that the primary hydration product of C3A was poor crystalline material. Breval 1166], in accordance with the above, found at the outset of C3A hydration the formation of a gel, followed by nonhexagonal hydrates. In some cases single crystals of cubic C3AH6 were observed. Further, hydration morphology was temperature dependent. Hot pressed calcium aluminate cement pastes [167] indicated by SEM almost featureless massive structure with essentially no visible porosity. SEM was used to examine the morphology of ettringite [168] (Figs. 13-14) produced from various reactions between gypsum and C3A, and from calciummagnesium sulphate paste hydrations. CH was always found to reduce the rate of ettringite formation. High w/s and high porosity, that is sufficient space, enabled the growth of large spherulitic ettringite crystals or slender needles; and in low w/s, short prismatic crystals were formed. In a discussion [169] the occurrence of topochemical initial reaction was suggested but this interpretation was rejected [170], Another discussion [171] supported the through-solution mechanism, but an early belief was reiterated, namely, that CaO was responsible for the expansive effect of Type K cement. In reply [172] it was stated that 1% free CaO in the above cement could not produce significant expansion in concrete under restraint. The advantageous role of CaO in expansive cements 1173], and the formation of aluminates in the limesinter process [174] were also studied. Ramachandran and Beaudoin [1751 investigated characteristics of hydrating Ci^AF pastes between 23 and 80 C with w/s ratios between 0.3 and 1.0. Morphology with a dense structure generally signified greater strength in this system. The sequence of products [176] formed in the hydration of C3A at various temperatures was: amorphous gel -*■ irregular flakes (mostly amorphous but with weak traces of C2AH8 and C^AH^) -► hexagonal flakes (C2AHÖ and C^AH^) -*· C3AHe single crystals (mostly icosahedral) -> C3AH6 aggregates of various habits (Figs. 15-17). It was suggested [177] that the initial reaction to produce gel was topochemical but this view was met with uncertainty [178]. Bradbury and co-workers [179] investigated the "conversion reaction" undergone by calcium aluminate cements. The strength development in C3A pastes [180] containing CaCl2 with or without gypsum was related to the morphological changes in the pastes. Regourd and co-workers [181] had studied.the hydration of three crystalline varieties of solid solution of C3A with Na20. The results obtained by SEM and EPMA had shown that the degree of reactivity decreased with increase of Na 2 0. Also, it was shown that the diffusion of chloride into the specimens was more rapid than for sulphate. They [182] also observed the hydration ^reactions of C3A-C3S by SEM and EPMA.

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Fig. 14. C3A in gypsum solution 5 min. Slender needles and also spherulites of ettringite in large cavities. [168 ]. The prehydration of cement was found to involve mainly the reaction of C3A with water vapour. It was shown [183-185] that the products of hydration were: gel, irregular hexagonal hydrates, hexagonal single crystals and aggregates and cubic aggregates [cf. 176]. At high temperatures and relatively low humidities, gel was the sole hydration product. At low temperatures and high humidities, hexagonal hydrates, well crystallized, appeared. The hydration sequence in liquid water was: gel, hexagonal hydrates and cubic hydrates. The hydration of C3A in different pH's in the presence of sulphate ions was studied [186], SEM was used to show that no ettringite was formed during the dissolution. The microstructure of aluminate cements [187] exposed to steam - CO at various temperatures was studied by Day and co-workers.

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Fig. 15.

C3A 72 hr hydration 10 C - hexagonal thin flakes C2AH8.[176].

Fig. 16.

C3A 47 d hydration 10 C - hexagonal aggregates 0,ΑΗ13.[176].

Electron and Optical Microscopy

Fig. 17.

753

C3A 6 d hydration 20 C - hexagonal aggregates and icosahedral C3AH5.U76].

Andreeva and co-workers [188 a-c] in a series of studies reported the microstructure of Ci+AF mixed with CH, gypsum and CaCl2· The low-temperature hydration of &+AF [189] in the presence of NaCl and CaCl2 was also studied. The hydration of aluminate and silicate phases was accelerated in the presence of CrO£ ions [190] and a chromium analogue of ettringite was observed. TEM and other methods were used in another study of the same team 1191]. Chromate ions were found to act as retarder to early hydration and affected composition and morphology of the hydration products. The influence of citric acid on the hydration of C3A with CH and gypsum was studied [192], A reaction scheme was proposed whereby citric acid was absorbed on C3A thus producing morphological and physical changes in the hydrate layers. In a similar study [193] it was shown that the ettringite crystals formed from a stoichiometric mixture of C3A and gypsum had a tendency to adhere together and were rather long; in the presence of CH the crystals studied were submicroscopic. Micrographs of C3A paste with and without 1-20 mol% of metal oxides as admixtures were shown [194], With no admixture, C3AH5 formed in considerable amount and in presence of some admixtures the formation of the cubic hydrate was hindered. The microstructure of hardened ettringite was also studied in the presence of the admixtures. All of them promoted crystal growth and produced some change in microstructure 1195]. A discussion to this study was presented [196] which corroborated with earlier work, but in their reply the authors stressed their observation regarding the influence of many metal ions on the crystal growth and microstructure of ettringite [197], The same team [198] concluded that some heavy metal oxides accelerated the formation of ettringite.

754

L. Ben-Dor

Hydration of C3A with gypsum [199] produced a gel with a foil-like form. The hexagonal phases, C2AH8, Ct+XH^, Ci^ASH^» appeared as hexagonal flakes, ettringite appeared as needles (perpendicular to the C3A surface) and the cubic C3AH5 appeared in many forms. Sodium aromatic sulphonates retarded the hydration of C3A with or without gypsum [200], After 30 hours ettringite was formed and after 72 hours monosulphate was obtained. Microstructure of C3A and Ci+AF with organic admixture was presented and the effect of retardation and water reduction was studied [201]. Somiya and co-workers [2021 observed the decomposition of C3AH5 at various temperatures up to 1400 C. SEM observations confirmed that the shape of the polyhedrons of the cubic aluminate were unchanged after the 1000 C decomposition reaction. Microprobe and microscope examinations were used to follow the reaction at the contact zone of calcite embedded in alumina [203]. The dominant phase was C12A7 with increasing amounts of C3A at higher temperature accompanied by a decrease in CA and CA£. The hydration of C 1 2 A 7 *·η the presence of CH resulted in the formation of (^ΑΗ13 and C2AHÖ [204], The plate-like morphology of these hydrates was illustrated and their relationship to flash setting was considered. Hydrogarnets containing low silica content were prepared hydrothermally [205]. It was found that the dimensions of the crystallites depended on the conditions of preparation and not on the silica content. Mehta [206-207] showed that ettringite formed in the presence of lime is colloidal rather than lath-like crystalline. This form adsorbed large quantities of water, caused inter-particle repulsion, slump loss in concrete and an overall expansion of the system. This view was discussed by both Mather [208] and Hansen [209] and resummarized by Mehta [210]. Ettringite under hydrothermal conditions was studied by SEM and other techniques [211]. Changes in crystal structure of ettringite on dehydration were investigated by electron microscopy and other methods [212]. It was shown that 30 moles of water can be present in the internal channels and surface defects of the crystal. The crystals disintegrated only when all but 6 moles of water were withdrawn. Another group [213] prepared large perfect crystals of ettringite and of calciummonosulphoaluminate and studied them by SEM. The optical characteristics of ettringite were outlined under natural, polarized or convergent light [214]. 5

CEMENT, MORTAR AND CONCRETE HYDRATION

The early electron microscope studies of cement concentrated on looking at the material between the sand grains: the tobermorite-like "crystals" [215-216], and the microstructure was related to various physical properties [217-219]. Curing temperature was found to have an influence on structure; the higher the temperature, the coarser the texture and the lower the strength [220], An extensive illustration of the wide uses of SEM in investigating hydration products was provided [221-222].

Electron and Optical Microscopy

755

Various studies were reported on the microstructure of cement paste and its relationship to strength development [223-229]. Lach and Bures [230] observed the microstructure of early cement pastes formed between 40 and 95 C. At 60 C, C-S-H gel formed in large amounts, and also tobermorite-like crys.tals, CH and ettringite, but no C3AH5 or hydrogarnet were detected. At 70 C the amounts increased and the crystals were better developed. At higher temperatures the crystals were coarser cf.[220], the structure more porous and ettringite was absent. Jambor [231-233] studied and reviewed the microstructure of cement paste. Theisen and Johansen [234] studied phase analysis of prehydrated cement. Wellcrystallized calcium monosulphoaluminate, at 120 C exposure, was observed. Low-temperature exposure did not produce well-crystallized hydrates. A study of the microstructure and pore structure of hardened cements was connected with surface free energy changes due to sorption of water [235]. The composition and structure of anhydrous phases in Portland cements, cement hydration constituents and their structure were reviewed [236]. The microstructures were discussed with respect to strength development. Nussbaum and co-workers [237], in a very detailed study, presented a qualitative correlation between reactivity, based on SEM observations, and compressive strength development. The properties and microstructure of lightweight aerated mortars were also discussed [238]. According to Hornain [239] the increase in strength of pastes and mortars of Portland cement are related to the transformation of the fibrous texture of high microporosity into a very compact texture due to the formation of microcrystals of calcite, from C-S-H rich in S1O2, and also of amorphous silica. The hydraulic activity of cement [240-241] was found to be dependent on the micromorphology, crystallinity and defects concentration of the main clinker components and crystal pattern of the CSH. Taylor described a new technique whereby the cement sample was hydrated directly on a SEM mount [242]. This technique enables observations of early hydration reactions and detection of both amorphous and crystalline phases. Methods were discussed [243] for controlling the microstructure of cement stone at 22-300 C. At temperatures <50 C the main factors determining structure formation were the concentration of the slurry, dispersion of the solid phase and hardening time. Above 75 C the C/S ratio had the principal effect on structure. Studies of Portland cement paste, combining SEM with EDXA, were reported by two teams [244-245]. A study combining SEM and TEM observations was also presented [246]. Cement phases, thinned by ion beam, were identified by TEM [247]. In discussing correlation between microstructure and strength of hydrated cements [248], it was maintained [249] and in general concurred [250] that strength could be represented as a plot of porosity vs. proportion of dense material in the sample. It was shown [251 ] that exposure of concrete to heat caused decomposition due to changes in microstructure and material properties. Cements which consisted of blast-furnace slag, gypsum and slaked lime [252] showed narrow tablet-like ettringite crystals which contributed to strength and needle-like crystals which inhibited the strength. From XRD and SEM it was found [252] that coatings form near the inlet of a cement kiln due to condensation of molten salt. The condensing droplets enclose dust particles or clinker carried with kiln gas, connect them with salt bridges and consolidate them on kiln walls. Using SEM as the main experimental tool, the formation of a C-S-H layer and CH crystals on the surface of%anhydrous cement clinker particles were observed [254].

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The hydration products of a variety of cementing compounds were examined [255] and strength was related to morphology. In a similar study [256] it was argued that high strength was associated with whisker crystals in the gel matrix and high microporosity. Drying hydrated Portland cement below 11% relative humidity [257] especially disturbed the structure of the material. The microstructure of cement was studied as a function of a variety of physical methods [258-259]. A review of analytical techniques used in order to obtain microstructural information was also published [260]. A cement soil stabilizer was used instead of Portland cement and mixed with clay minerals (sludge) to give a better hardened specimen [261], Ettringite played an important role in the quality of the material. A least four or five distinct varieties of C-S-H products of Portland cement paste exist, in consequence, Diamond suggested the terms "C-S-H gel" and "substituted C-S-H gel" in his nomenclature guide [262], Regourd and coworkers [81] in a 1974 report supported the view that C-S-H may form a through-solution mechanism. This claim was based on SEM observations of C-S-H deposition on a thin nickel plate. A different view was put forward by Kittle and Castro [263] who concluded that topochemical growth rather than Williamson's [219] through-solution solidification was responsible for the hardening of cement paste [cf. 172], The microstructure of cement paste in an 84-year-old concrete structure was examined [264] and lath-shaped particles, C-S-H gel, and platy-shaped intergrowths with hexagonal angles (in some cases) were found. Marchese [265] studied noncrystalline CH in ancient nonhydraulic lime mortars from fragments of old mosaics. SEM showed uneven agglomerations of grains forming uneven porosity. Perhaps core CH was covered with layers of CaCÜ3. The surface of a 30-year-old dam was quite cracked [266]. Samples of material showed' evidence of a formation of reaction products, resembling zeolite A, within the aggregate and matrix. Carbonization [267] was found to change composition of cement: tobennorite was decomposed to vaterite, calcite and gel, but no substantial change was found in the morphology of the cementing phase. Aggregates limited the formation of ettringite and portlandite and new crystal hydrates were formed [268]. The transformation of ettringite to calcite in cement exposed to carbonated water wa*s studied by SEM [269]. The corrosion of concrete [270] was studied by electron microscopy (and other methods) and was shown to be a result of attack of free alkali bases and carbonates with the aluminate solutions. Concrete was also damaged by alkali-aggregate reaction [355]. A monograph by Ramachandran [271 ] reviewed the essentials of cement science and the hydration behaviour of the individual cement minerals in the presence of CaCl2, and its influence on characteristics of cement and concrete as observed by SEM (and other techniques used in the study of cementitious sytems). Another study dealing with cement containing up to 3.5% CaCl2 was presented by the same laboratory [272]. The microstructures of the pastes were compared for equal degrees of hydration. Super-sulphated cement [273] having a rapid increase in strength up to 7 d contained large lath-like crystals of ettringite. The subsequent slower strength increase was due to the formation of both granular and platy C-S-H. TEM was used [274] to study the micromorphology of cement hydration products with and without gypsum. The corrosive effect of sulphuric acid on mortar specimens [275] and the microstructure of steel-corroded concrete [276] was also studied.

Electron and Optical Microscopy

757

The effect of KaCl, artificial and natural seawater, [277-279] on the durability of cements was studied and changes in morphology were observed. Two reports [280-281] discussed the deterioration of concrete exposed to seawater. Exposure tests dating from 1905, as well as modern laboratory investigations using SEM and EDXA were summarized. A 30-year-old concrete [282] deteriorated by dry winds, salt-laden winds and solar radiation was studied. The fibrous and more equant morphologies were shown in micrographs. Correlations between structural-morphological modifications of mineralized Portland cement clinkers and their mechanical strength was shown [283] for the following admixtures: CaSO^, FeSOt,, Α1 2 (50^) 3 , alkali and MgO. The three sulphates increased the strength. The main pre-requisites for good clinker hydraulic activity are a microcrystalline texture and an increase in C3S crystal morphology in two directions. The early hydration products of a chromium-bearing super high early strength cement were found to include thick CH plates and thicker ettringite needles than were found in the absence of chromium [284]. It was considered that early strength refelcted higher paste density associated with thicker plates and thick, elongated ettringite. The influence of various electrolytes on the strength development in cement pastes was reviewed [285]. It was proposed that at equal degrees of hydration the morphological and structural nature of the paste were important factors in determining strength. Structural defects also influenced mechanical properties. The effect of Pb(NÜ3)2 on early hydration [286] and on the physical properties [287] of cement pastes was studied. The additive was found to have a retarding effect and at high concentrations it caused deleterious cracking of the pastes. The effect of sodium tripolyphosphate on Portland cement paste was explored [288] and the chemistry of early hydration and development of structure during setting [289]. A systematic SEM investigation on cement mortars containing eleven types of commercially available air entrainers was undertaken [290J. Numerous microcracks, having a wide variety of patterns, were observed in the cement paste. Surfactants [291 ] improved tensile strength of hydration products by improving cement-aggregate bond. Surfactants, such as Na2SiF£, were used in order to study their modifying effect on the crystal morphology of CH during crystallization [292]. Whereas CaO hydration produced colloidal material, the above admixture caused the growth of macrocrystals [292]. The influence of organic admixtures on the microstructure of Portland cement pastes was also explored [294-295]. Cements to which triethanolamine and boric acid were added have been studied [296]. Micrographs were made on high early strength pastes [297 ] with and without lignin-based water-reducing commercial admixtures. Physical and structural-properties of the paste were modified by the admixtures. Collepardi and Massidda [298] investigated the influence of conventional and super-water reducers on the morphology of hydrated cement. In the presence of a water-reducing agent (aromatic sulphonate) [299] the formation of ettringite, in Portland cement, was suppressed and also the hexagonal plates of CH which appear in early hydration. The microstructure of low porosity Portland cement paste with lignosulphonate and an alkali carbonate or bicarbonate instead of gypsum as admixtures [300] was described. Types I and II C-S-H gel were generally not observed in these pastes. At early age thin plates of C-S-H appeared, subsequently fol-lowed by Type III gel. Products analogous to ettringite did not seem to be produced. After approximately 2 days a massive structure formed. This microstructure was not developed when low porosity cement was bottle hydrated: space was then freely available and the admixture solution concentration levels were correspondingly decreased. The same system was studied [301] and similar results obtained, viz. Type III C-S-H was found independent of admixture used.

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The microstructure [302] of very high strength, hot-pressed cement pastes was found to be very dense. The effects of applications of heat and pressure on the morphology of hydrating cement paste were illustrated [303]. In addition to the usual ill-crystallized C-S-H gel material, well-crystallized hydrates including C5S2H, C 3 SH 1# 5, C3AH6 and Ci^He were detected in hotpressed pastes. Hot-pressed cement [304] was investigated in presence of admixtures. Little difference was found in the microstructure of pastes prepared with or without admixtures. Morphology and microstructure of autoclaved clinker and slag-lime paste were studied [305]. Hydration products containing crumpled foils and tubular masses of C-S-H and a few cubic crystals of hydrogarnet appeared only during the initial stage of the reaction. In clinker-sand mixtures the C-S-H phase only was identified. In slag-lime hydration both hydrogarnet and C-S-H phase were displayed. In an optimum mixture containing sand both ill-crystallized and 11 A tobermorite were the main products. The same group [306] studied the morphology and microstructure of autoclaved slag-clinker with and without sand. The first mixture contained nearly amorphous, fibrous and radial plates of C-S-H, large cubes of hydrogarnet (mainly C3ASH1J and hexagonal CH. The second composition was associated with the formation of semi-crystalline, low-lime tobermorite. Strength development was also related to the microstructure. The effect of w/c ratio on frost resistance, structure and strength was investigated [307] and also that of variations in microstructure on frost resistance of hardened paste [308-309], The influence of freezing and thawing cycles in the microstructure of cement pastes cured for various periods was studied [310], The severe loss of strength was explained by the development of numerous large crystals of CH' surrounded by voids. It was found useful to inspect early stage hydration on frozen specimens of cement paste by SEM [311j. Regulated jet (set) cement [312] was studied and micrographs revealed that the initial hydration products were needle-shaped ettringite crystals, growing on the clinker and anhydrite grains. Within hours the close-knit structure changed to hexagonal plates of the monosulphate. The growth of ettringite followed that of the monosulphate to achieve a maximum and decreased again. The C-S-H material was wrapped around the crystals. Uchikawa and Uchida [312] studied the influence of additives on regulated-set cement. C3S started to hydrate only after the hydration of CiiAyCaF2 slowed down. Surface active agents influenced the habit and size of the ettringite crystals formed. A team from the same lab [314] connected composition and pore structure of jet cement with strength. Their results coincided with the crack distribution in fracture surfaces as observed by SEM. Two rapid-hardening cements were subjected to three hydration treatments [315]. Curing at 70 C resulted in large grains covered with gel-like product; the above curing, following a 20°C pre-treatment, resulted in crystalline products with great morphological diversity; while curing at 20,C only, produced bandlike hydration products with a felt-like structure. Analytical and high resolution electron microscopy was used to characterize hydrated ultra-rapid cement [316], The microstructure and composition of C-S-H, ettringite and C3ASH were investigated.

Electron and Optical Microscopy

759

Portland cement fracture surfaces [317] (Figs. 18-20) and shrinkage microcracking in concrete pastes were examined [318J. The results of SEM investigations of the paste-aggregate interfacial zone were presented by Barnes [319]. Initially a duplex film of oriented CH backed with a single layer of C-S-H gel particles was deposited directly on the surface of the aggregate, and a few large hexagonal CH crystals projected back into the cement paste. A secondary layer of these crystals filled up the porous zone behind the duplex film thus attaching the aggregate firmly to the bulk paste. The original findings of Hadley [320] whereby C3S grains dissolved out from within shells of early hydration products were confirmed and occurred not only near aggregate surface but also in bulk cement paste. Another study 1321 ] of interfacial zone employed SEM and TEM on ultra-thin sections normal to the interface. Pore sizes and the evolution of the contact zone structures were discussed by Grudemo [322] with respect to the deformation and fracture mechanism. The growth of gel and the structure of the hydration products were also reviewed.

Fig. 18.

APC - Y

(a) PC 24 h hydration, gel fibres, (b) magnification.[317].

higher

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L. Ben-Dor

Fig. 19.

(a) PC 21 d hydration, CH pla-telets, (b) higher magnification. [317].

Fig. 20. As 19, rosette of CAH.[317].

Electron and Optical Microscopy

761

Diamond [322] summarized the structures and reactivities of various silica and silicate aggregates. Extensive studies of the microstructure of the interfacial zone between cement paste and aggregate [324-330] revealed characteristic portlandite-CSH gel duplex structure. The same morphology was shown in mortars. The presence of hollow-shell hydration (Hadley grains) in the interfacial region was observed. When samples tested in wet and dry conditions, under static and fatigue loadings, were observed by SEM [331 ] it was found that the fatigued samples showed significantly more microcracks than failed samples. A microstructural study of hardened cement pastes showed the existence of three types of channels along grain boundaries [332], As hydration proceeded, these channels were filled with ettringite and CH. The fatigue of cementitious materials [333] was examined by studying microcracking. The presence of uncombined water in the matrix affected static strength. The process of cracking in mortar was observed within a SEM chamber [334]. The crack was found to be tortuous, somewhat branched and discontinuous. A comprehensive review in the area of expansive cements [335] contains data on the crystal data and morphology of ettringite. A report was presented on the influence of curing temperature on hydration of pastes of expansive cement [336], Large quantities of well-developed, columnar ettringite crystals were observed at higher curing temperatures, whereas large hexagonal plates of CH formed by hydration of free CaO lost shape when the temperature was about 80 C. At the same meeting [337] a report dealing with the effect of calcium sulphate on the expansion of Portland cement, containing deadburnt CaO as expansive agent, was presented. In expansive cement pastes [338] correlation was found between surface area, pore volume and microstructure. Expansive cement [339] was prepared from kaolin, CaC03 and gypsum. The morphology was studied and correlation was made between the mechanism of hydration and pore size. Expansion of cement [340] was caused by the growth of ettringite crystals when cement was hydrated in the presence of free CaO, anhydrite and C3A. The monosulphoaluminate did not contribute to expansion but free CaO contributed to it and controlled the rate of crystal growth of ettringite. Since 1976 Double and co-workers have been devoting a great deal of thought to the mechanism of hydration of cement narrowing themselves to the silicate phases. A correlation was found between features observed in hydrating cement paste by SEM and those revealed by TEM for "silicate gardens" [341], The fascinating growth forms in "silicate gardens" are described in textbooks of chemistry see, for instance, Sherwood Taylor [342]. A popular presentation appeared by the same team [343] , and the view proposed was that the hardening of cement was due to osmotic pressure. This proposal was based on an earlier one suggested by Powers in 1961 1344], and the idea was that the tubular fibrils of C-S-H were formed via a semipermeable membrane. In further studies

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[345-346] (Figs. 21-24) high-voltage electron microscopy was used to study the mechanism and driving force of early hydration. The hydration sequence was explained in terms of gel formation around the grains, as a result of osmotic pressure effects and a secondary fibrillar growth of gel after osmotic rupture of the coating. Jennings and Pratt [347] obtained micrographs of hydration products of Portland cement and concluded that "osmotic" mechanism for cement hydration was viable for some of the morphologies obtained but an alternative mechanism is more suitable for others. Using a STEM (Scanning TEM) [348] the same team supplied evidence for the existence of a membrane surrounding cement particles during the induction period. In a further study [349] cement samples were studied in the moist state in an environmental stage of the high-voltage EM. Square-ended fibres containing Al, S, Ca and some Si, hollow structures, C-S-H sheet-like foils and small hexagonal crystals (CH) were observed. It was proposed that the rolling up of the sheets produced the fibrous or acicular particles. Birchall and co-workers [350-351 ] also voted for the "osmotic" mechanism. Using TEM [351] it was found that the initial hydration products of the aluminates were noncrystalline hydrates (CASH) of tubular habit. The properties of these Type II fibres suggested that an osmotic bursting model, as proposed above for C-S-H, could account for aluminate hydration products.

Fig. 21.

SEM PC 30 d hydration, hollow shell of hydration enclosing original grain. [345] .

Electron and Optical Microscopy

Fig. 22.

763

High-voltage EM: (a-c) sequence within 20 min of mixing, (d) after 3 hr. [345J.

The existence of the hollow cement tubules was confirmed by realistic w/c ratios [352J by utilizing multiple electron microscope viewing: TEM, SEM, STEM, of the hydration products. Their behaviour, in particular damage to them, was noted under the electron beam. However, microanalysis of these tubes along with selective phase hydration experiments showed unambiguously that the "reverse silica garden" mechanism cannot be solely responsible. Probably a more complex chemical multi-phase system operates in which rheological factors are also important or rather may turn out to be key factors in tubular growth. A recent report from the Oxford group [353J reaffirmed the earlier osmotic mechanism based on semipermeable properties not confined to silicates but also including aluminates and ferrocyanides, and probably to system where a continuous gel membrane is precipitated between two aqueous solutions of differing compositions. A special report [354] on cement hydration was summzrized by Birchall. Special emphasis was placed on the analytical electron microscope and on electron microscopy of cement particles in the process of hydration. The following participated: Diamond contrasted examination of dry specimens by TEM, STEM, etc., with that of "wet cell" electron microscopy. He strongly advocated a multi-disciplinary attack on the problems of cement hydration. Dent-Glasser applied herself to analytical electron microscopy and showed that C/S ratio for C3S hydration was constant with time as 1.5-1.6, whereas in Portland cement there was variation of composition with time. Double used high-voltage electron mieroscopy to show tubiform excrescences of hydrated gel formed by an osmotic mechanism. Bailey and Chescoe described the same

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outgrowths but used an analytical microscope for elemental analysis of them. It was shown that hollow calcium sulphoaluminate fibres were found to be produced from C3A hydration. Pratt and Jennings showed evidence for the formation of a membrane at the gel-like surface of a hydrating cement grain, with the exfoliation of the membrane as sheets which layer coiled to form tube-like structures. The observed accentuated growth of fibres could not be explained by a "through-solution" mechanism and supported the osmotic one. Birchall proposed that an amphorous membrane of calcium sulphoaluminate allowed osmosis across it. Groves used analytical electron microscopy to identify clinker phase and the presence of an overlying, non-crystalline gellike layer. Ball showed that treatment of white Portland cement with salicylaldehyde produced a change in hydrate morphology — very long fibrous growths.

Fig. 23.

High-voltage EM: (a) fibrillar CSH gel 1 d, (b) greater detail.[345].

Electron and Optical Microscopy

765

Fig. 24. TEH dried fibrillar CSH suggesting tubular morphology. [345].

6

SLAG CEMENT, BLAST-FURNACE CEMENT,

Satarin [356] had reviewed seventy-eight publications, mostly of Russian studies, on Portland-slag cements. From electron microscopy it was indicated that the early stages of the hydration process involved slag grains as centres, around which the aluminate sulphate hydrates and amorphous silicate hydrates were formed. The high durability of this cement to sulphate was attributed to the microstructure which consisted of denser formation of C-S-H gel and smaller amounts of crystalline CH than are found in hydrated Portland cement paste. When CaCl2 1357] was added to Portland blast-furnace slag cement the microstructure was altered to a more open pore-structure. A comprehensive review [358] covered the physico-chemical processes of rapid hardening and high-strength slags. The microstructure of the clinkers was discussed. Another report [359] dealt with the microstructure of hydrated synthetic slags at 5WC.

Polymer-impregnated concrete. Fibre-reinforced cement.

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The microstructure of two different slags [360] was related to the products formed in corresponding hydrated slag cements. For early age both clinker and slag were covered by C-S-H derived from the clinker. At 28 days the beginning of hydration of the slag could first be detected. The morphology of the ettringite needles depended on the amount of slag. Blast-furnace slag-gypsum mixtures [252] activated with CH gave rise mainly to C-S-H gel and narrow, paper tablet-like ettringite particles; the development of needle-like ettringite was found to be deleterious to strength. The hydration of industrial slags in the presence of alkaline solution produced C-S-H and hydrogarnet [361] as was identified by SEM. Two reports [362-363] dealt with resistance of Portland blast-furnace slag cements to seawater. The granulated slags were found to increase the resistance of the cement to chemical attack. Blast-furnace slag in the presence of gypsum [364 I was hydrated at 70 C and the material formed contained many voids. At 180 C the material was more compact because the pores were filled with plazolite. Sulphated slag cement mortars containing gypsum and slaked lime [365] were carbonated with CO2. The carbonation proceeded easily, ettringite and C-S-H (I) were decomposed while gypsum, CaCÛ3 and amorphous phases were formed. The pore size distribution and morphology of hardened slag-lime-gypsurn was also studied [366]. Ettringite and CSH were the main products when supersulphated slag cement was hydrated in the presence of lime [367]. Impregnation with polymer [368] remarkably improved the structural properties of cement and mortar composites. A unique method of investigating the geometry of the pore system in hardened cement paste 1369] was by impregnating and polymerizing a monomer in situ within the paste, then dissolving away the paste and examining the replica of the pore structure using electron microscopy. In microscopic studies polymethylmethacrylate (PMMA) had been observed to either fill br line the surfaces of pores in hardened cement matrices and to have a glassy apearance [370-371 J. The PMMA structure in polymer-imprégnated concretes appeared to approximate a negative replica of the cement pore structure having a three-dimensional fibrous network. Polymer added to concrete or cement during mixing [372-373] modified the microstructure and increased the number of planes contacting the newly produced phases. SEM was used for explaining the mechanism of reinforcement of Portland cement pastes by vinylidene chloride, and styrene-butadiene copolymer latexes [374] (Fig. 25). Another study showed [375] that organic resin was adsorbed and partly filled the pores of cement paste. The influence of low molecular weight polymers on. the hydration and characteristics of cement minerals was also examined [376]. It was possible to observe microcracks [377] in a modified vacuum-impregnation technique, in which the sample and the resin were degassed separately. This enabled a three-dimensional picture of the pore structure to be obtained. The structure of gels obtained from reaction of anhydrous cement and methacrylate cement suspension was studied [378]. In a recent review [379], the bonding between polymer and the concrete matrix was discussed. A most interesting cementitious material has been developed — a "glass ionomer" cement or ionic "polymer" [380]. The material is based on a hardening reaction between a powdered ion-leachable aluminosilicate glass and acidic polyelectrolyte solutions. The cement formation and reaction between these glasses and polyacrylic acid solution have been characterized by various methods including SEM studies. The glass particle surface is converted into a siliceous hydrogel, and the metal ions go into solution to form a metal polyacrylate gel matrix. The structure of glass ionomer cements was examined by SEM, TEM and phase-contrast microscopy [381-383].

Fig. 25.

Styrene-butadiene copolymer latex modified mortar. (a) Microfibres of polymer retaining substrate and overlay of mortar after fracture along interface. (b) Microcrack between sand and mortar spanned by polymer fibres. (c) Microcrack halted by microfibres. [374].

c^

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768

Although corrosion of asbestos fibres [384J due to the alkalinity of cement paste was observed after long-time performance, it was suggested that this was not a harmful phenomenon since the corrosion product protected fibres from further attack 1385]. Asbestos reinforced cement was studied [386] (Figs. 26-28) and also interior surfaces of new and used asbestos-cement pipes t387]. The interface region between cement paste and steel fibres [388] was studied and CH was found there. In a similar study [389] inclusions of C-S-H gel were also found [cf. 324-327]. The effects of fibre reinforcement on the physicochemical and engineering properties of hardened cement pastes was studied with asbestos, glass fibres and polymer-coated glass fibres [390-391 ] The fibres affected the habit of the hydration products.

Fig. 26.

Fig. 27.

Fractured asbestos-reinforced cement. are seen. [386 ].

Fibres

Emergence of large fibre of asbestos.[386].

Electron and Optical Microscopy

Fig. 28.

769

Flower-like ettringite crystals characteristic of solution growth due to asbestos in paste.[386].

The interfacial bond strength between cement and various glasses was examined [392J, and no indication of severe etching or chemical reaction was discerned after long age. Majumdar [393] (Figs. 29-33) studied the fracture of frc with particular attention to the interface. SEM micrographs of fracture samples [394] of plain and fibre-reinforced mortars were compared.

CEM-FIL glass fibres (high zirconia content) which are alkali resistant (pH 12-13) were compared with basalt fibres (mineral rock) and jute fibres (vegetable source) [395]. The fibres were dipped in cement aqueous extract of pH = 13.36 and the micrographs showed the superiority of CEM-FIL over other glass fibres (A or E). The basalt fibres, due to the presence of AI2O3, were also alkali resistant. On the other hand, the jute fibres were found unsuitable as a reinforcement since they are composed of cellulose and lignin which are not alkali resistant. Microscopic studies [396J indicated that the morphology of hydrated CEM-FIL reinforced cement for accelerated conditions (high temperature hydration) was akin to that observed in weathering exposure.

Fracture surfaces of 2-year-old specimens of glass-reinforced concrete [397] showed signs of deterioration. CH was observed at the interface when no blast-furnace slag was added. In all cases embrittlement coincided with the appearance of etch pits and massive precipitation around the glass fibres.

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L. Ben-Dor

Fig. 29.

Glass-fibre-reinforced cement - glass strand (diameter of one filament = 10 urn).[393],

Fig. 30. Glass-fibre-reinforced cement - glass filament (diameter of one filament = 10 pm).[393].

Electron and Optical Microscopy

Fig. 31.

Interfacial bond in glass-fibre-reinforced cement (diameter of one filament = 10 ym).[393].

Fig. 32.

Smooth surface of alkali-resistant glass after reaction with cement extract solution. [393].

771

772

L. Ben-Dor 7

FLY-ASH, POZZOLANA AND INORGANIC CEMENTS

In one of the early studies dealing with the reaction between fly-ash and Portland cement [398] it was shown that CH produced by cement hydration adsorbed on the surface of the fly-ash particles. This adsorbed CH appeared to form a membrane over the particles and a film of water, or water gap, existed at the interface, especially at early age. Connection between structure and properties of cements containing fly-ash was explored [399]. Fly-ashes and fly-ash cements from different countries were reviewed [400]. Strength behaviour over a long period of time was deduced from SEM studies. Strength development, which is a slow process, depends upon filling up of capillaries with the products of the pozzolanic reaction. Using electron microscopy and microprobe analysis [401], it was shown that initially the fly-ash particles were not chemically bonded with the hydration products of the cement paste, but were eventually involved in the hardening process as a result of surface corrosion by CH. Using SEM techniques it was found that pozzalanic products were precipitated in the water film at the interface, and that surface layers of the fly-ash grains were gradually consumed [402]. Eventually the particles were coated by their own reaction products and further pozzolanic reaction depended on CH diffusion. A study of the mechanism of pozzolanic action of fly-ashes in cements [403J, provided detailed models and micrographs of the process. The reaction between power station fly-ash and CaO under hydrothermal conditions [404] was investigated.

Fig. 33.

Damaged surface of E-glass after reaction with cement extract solution. [393 ].

Electron and Optical Microscopy

773

Collepardi and co-workers [405] studied the morphological structure of compacted mixtures of CH and pozzolana. Microstructure and other characterization data were reported to confirm the effectiveness of siliceous fly-ash and metallurgical slags in stabilizing high MgO cements. Duplex films were found to occur around all grains from fly-ash bearing Portland cement pastes [406]. The consequence of SEM observations of hydration products, without and with HCl etching, was that some of the C-S-H bearing shells around grains of Portland cement might represent the effects of deposition from solution onto surfaces of grains that are chemically inactive. A mixture of five Japanese pozzolanas and pure C3S were hydrated 1407] and the pozzolanas were found to accelerate C3S hydration. Autoclaved fly-ash cement mixtures were studied [408-409]. Based on SEM observations [410] it was confirmed that higher reactivity was obtained for high-lime fly-ashes and that the latter itself showed cementing properties in contrast to the behaviour of low-lime fly-ashes. Micrographs [411] illustrated the fly-ash particle morphology and the alkali content of the pore solutions was examined as well. Santorin earth was blended with Portland cement and its pozzolanic activity was studied [412]. The microstructure of Sorel cement, containing MgO, was found to consist of regions of fine growths of needle crystals and regions denser and more homogeneous in appearance [413], SEM observations were related to cement formation. Shrinkage cracks had smooth sides with lack of needle-like crystals indicating that these were not pulled apart during the cracking process. In the hardening process, magnesium oxychloride crystals grew rapidly and filled the space available between MgO grains with mechanical interlocking responsible for the onset of rigidity and stiffening. In a discussion to the above study [414] another possible interpretation was offered based on the thickness of the conducting coating used. The former team stressed [415] that the microstructural details observed did not change when carbon coatings, transparent to secondary electrons, were used. Set Sorel cement was treated in water at 85 C exhibiting improved mechanical properties [416]. SEM revealed an amorphous-like microstructure with a glassy and compact appearance. The smooth monolithic regions, rather than the needle-like regions, contributed to the strength properties of this cement. The system C-A-S-M was studied [417] under hydrothermal conditions both by SEM and XRD, and also mixtures of MgO and silica gel [418]. Newesely [419] studied the microsfructure of cements of zinc phosphate with aluminosilicate and phosphoric acid.

774

L. Ben-Dor 8

ALKALI SILICA/AGGREGATE CEMENTS

Pastes prepared from CH, C3A and C3S as binders and dacite tuff, fly-ash, kaolinite and sand as aggregates were shaped into cubes, cured and studied by a variety of methods including SEM [420]. Certain aggregates were found to react with alkali in cement to produce stains and pop-outs on concrete surfaces [421]. Using SEM and EPMA it was not possible to identify positively the materials but they were found to contain iron. Mixtures of autoclaved quartz and hydrated lime were examined morphologically [422] and fibrous or crinky foils of semi-crystalline material (C-S-H II?) were revealed after 12-24 hr and platy crystalline material (C-S-H I?) after 48 hr. CaO and SiÛ2-source materials with various additives were used for the formation of tobermorite [423]. Initially C-S-H gel was obtained which transformed to 11 A tobermorite. The reaction rim between cement paste and opal particles were examined by SEM and EPMA [424]. The composition of alkali-silica gel in the cracks was also examined. Sauman [425] studied the products of steam-cured building materials and calcium silicates and related technical characteristics with morphology of 11 A tobermorite. Later he studied the morphology of the gels and several varieties of 11 A tobermorite as functions of type and grain size of the filler used. Electron microscope studies [426] of lime-silica filter pressed products were reported and industrial products made from dehydrated and pressed slurries were examined [427], The identification of produces produced from hydration of lime-silica mixtures and characterization of their morphologies by SEM were reported'by several investigators [428-430]. In general the products are well crystallized 11 A tobermorite, xonotlite and sometimes less crystallized C-S-H phases. Hasaba and co-workers [431] showed that fibrous crystals are formed on the alkali-silica gel which covered the opaline aggregate during storage.

The use of fine quartz sand resulted in a decrease of the basicity of hydrated silicates and hydrogarnets formed in concrete [432]. The reaction between lime and clay was limited in the presence of high gypsum content [433]. With sand soil, a reticulated network of C-S-H gel and plate shaped calcium aluminate hydrate were formed. The morphology of needle-like ettringite formation stabilized by lime and gypsum varied with lime/gypsum ratio. Suspension of quartz and CaO at 80-120°C were studied and different hydrates were obtained for different C/S ratios [434]. A cement void stabilizer was mixed with sludge (clay minerals) [261]. The amount of clay minerals in the sludge, and the amount of ettringite formed, played important roles in the solidification process.

Electron and Optical Microscopy

775

Beltane opal is a standard reactive aggregate for alkali-silica reactions. The material ground to pozzolana size was grossly heterogenous [435 j and the reaction product in mortars was spongy with intrinsically fuzzy outlines. The surface microstructural features of Ottawa sand were examined [436], The observed features included large areas of rounded grain surfaces which under high magnification consisted of sharp hills and valleys. Areas of smooth planar surfaces were thought to represent cleavage planes. Large dish-shaped concavities might have been formed from violent grain-to-grain contact. SEM was used to study aluminous cement hydration in the presence of calcareous and siliceous aggregates [437]. 9

PLASTERS

The hydration of a- and 3-hemihydrates was studied [438] and the same topic revisited later by the same team [439J. The products of dehydration (under low vapor pressure) of the dihydrate of CaSO^ to ß-anhydrite III were different from those of the dehydration of 3-hemihydrate to p-anhydrite III [440]. Murat [441] used SEM to study the morphology of by-product gypsums. The morphology depended on the origin of the sample and the ions present during crystallization. A close relationship existed between the morphology of the crystals and the impurities. Another report from the same lab [442] showed that an entirely different behaviour was observed when B-hemihydrate was exposed to either 80% rh or to saturated water vapour. In yet another report [443] the surface fractures of natural and synthetic anhydrite were presented. The crystal structure and morphology of the natural anhydrites were rather similar and were characterized by orthorhombic cleavage planes. The synthetic anhydrites differed considerably depending on the method of preparation. The reactivity was found to vary with the microstructure of the hydration products of the anhydrites. Gypsum research carried in Würzburg, Germany, was described by Scholze [444]. The bond between gypsum and concrete was demonstrated by micrographs and the microstructure of gypsum at the interface was dependent both upon the type of gypsum plaster and the condition of the concrete surface. Micrographs were presented of samples of pure gypsum heated to various temperatures in the range 50-1100 C [445]. As the temperature increased there were substantial changes in surface features, such as cracks and fissures. A magnesite-gypsum cement containing 25% gypsum was examined [446]. SEM micrographs showed deformed gypsum crystal masses and incompletely hydrated magnesite. In a study devoted to examine grain size and texture of raw materials, changes in textural properties of gypsum during dehydration and rehydration were also studied [26]. In a 1977 RILEM Symposium [447-449], SEM was employed to study a series of specimens of gypsum and anhydrite according to their origin and genesis. A variety of textures and crystallization states were observed, such as: saccharoidal gypsums, alabaster, fibrous, porous and siliceous gypsums. In the case of anhydrite, the crystal morphology and habit were less diverse. In the study presented by Hamori [449 ] the process of hydration of activated Hungarian natural anhydrite was presented.

APC - Z

L. Ben-Dor

776

The effects of some additives on set gypsum were examined [450]. SEM and optical microscopy were used to measure the effects on crystallization. A new method was described for measuring the columnar crystallites of gypsum by SEM [451]. Polyvinyl acetate improved the workability of gypsums due to lower intergranular friction [452], DEDICATION This chapter is dedicated to my beloved teacher, the late Professor A. Glasner, who led me through the maze of thermal analysis. ACKNOWLEDGEMENT The author thanks the publishers for copyright permission to reproduce figures and is grateful to all the colleagues who were willing to allow their data to be used in this chapter. The American Ceramic Society: 1. S. E. Ampian and E. P. Flint, Amer. Ceram. Soo. Bull. _52> 604(1973), ref. 25, Figs. 1-3. 2. L. Ben-Dor, D. Perez and S. Sarig, -J. Amer. Ceram. Soo. _5£, 87(1975), ref. 43, Figs. 6-7. Elsevier Scientific Publishing Company: 1. V. S. Ramachandran and P. J. Sereda, Thermochim. Aota _5, 443(1973), ref. 183, Figs. 16-17. 2. L. Ben-Dor and D. Perez, Thermochim. Aota J_2, 81(1975), ref. 43a, Figs. 4-5. 3. V. S. Ramachandran and G. M. Polomark, Thermochim. Aota _25, 161(1978), ref. 251, Fig. 20, Pergamon Press Ltd. 1. V. S. Ramachandran, Cem. Conor. Res. 9_ 677(1979), ref. 69, Fig. 8. 2. D. Ménétrier, I. Jawed and J. Skalny, Cem. Conor. Res. _1_0, 697(1980), ref. 71, Fig. 9. 3. V. S. Ramachandran and R. F. Feldman, Cem, Conor. Res. .3» 729(1973), ref. 77, Figs. 10-11. 4. V. S. Ramachandran, Cem. Conor. Res. _3, 41(1973), ref. 79, Fig. 12. 5. M. Collepardi, S. Monosi, G. Moriconi and M. Corradi, Cem. Conor. Res. _9, 431 (1979), ref. 118, Fig. 13. 6. Z. Sauman, Cem. Conor. Res. J_, 645(1971), réf. J24, Fig. 14. 7. L. Massida and U. Sanna, Cem. Conor. Res. £, 127(1979), ref. 179, Fig. 15. 8. R. Kovacs, Cem. Conor. Res. _5> 73(1975), ref. 195, Fig. 18. 9. J. J. Beaudoin and V. S. Ramachandran, Cem. Conor. Res. 5^ 617(1975), ref. 207, Fig. 19. Chapman & Hall Ltd. 1. Walsh et αΙ.Λ J. Mater.

Soi.

£, 423(1974), Figs. 2,3,6.

Electron and Optical Microscopy

777

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37.

Midgley, H. G., The Chemistry of Cements, éd. H. F. W. Taylor, Academic Press/London (1964), Vol. 1, Chap. 3, p. 89. Grudemo, A., ibid., Vol. 1, Chap. 9, p. 371 (1964). Gard, J. A., ibid., Vol. 2, Chap. 21, p. 243 (1964). Chatterji, S., Cem. Teohnol. _6, 5 (1975). Mindess, S. and Diamond, S., Cem. Conor. Res. J_0, 509 (1980). Volkonskii, B. V., Chistyakova, A. A. and Zhmodikova, M. S., Tsèment (12) 11 (1971). Timashev, V. V., Malinin, Yu. S., Papeashvili, Sh., Ceram. Abstr. 56, 190-(1973). Diamond, S., 6th ICCC, Moscow (1974). Hantshe, H., Silicates Ind. 39_, 155 (1974). Diamond, S., Young, J. F. and Lawrence, F. V. Jr., Cem. Conor. Res. _4, 899 (1974). Barnes, P., Fonseka, G. M., Ghose, A. and Moore, N. T., J. Mater Soi. J_4, 2831 (1979). Skalny, J. and Maycock, J. N., J. Amer. Ceram. Soo. 5J, 253 (1974). Skalny, J., Mander, J. E. and Meyerhoff, M. A., Cem. Conor. Res. 5_> ]1 9 (1975). Moore, N. T., Sarkar, S. L. and Jeffery, J. W. , World Cem. Teohnol. _8, 240 (1977). Barnes, P., Moore, N. T., Jeffery, J. W. and Sarkar, S. L., World Cem. Teohnol. 9_y 50 (1978). Barnes, P., Moore, N. T. and Sarkar, S. L., X-ray Speotrom. 7_> 1Z*5 (1978). Sarkar, S. L., Indian Conor. J. _51_, 283 (1977). Barnes, P., Jeffery, J. W. and Sarkar, S. L., Cem. Conor. Res. j8, 559 (1978). Lukas, W., Rveck, R. and Hagleitner, K., Zem.-Kalk-Gips _30, 328 (1977). Chromy, S., Zem.-Kalk-Gips 27_, 79 (1974). Butt, Yu. M., Timashev, V. V. and Osokin, A. P., 6th ICCC, Wsoow (1974). Yamguchi, A. and Takagi, Sh., 6th ICCC, Moscow (1974). Malinin, Yu. S., Papiashvili, U. I. and Yudovich, B. E., Chem. Abstr. 8£, 184669 (1978). Papiashvili, U. I., Chem. Abstr. 8_9, 94122 (1978). Deloye, F. X. and Louarn, N., ButïT Liaison Lab. Ponts Chaussées (Paris)

22, 71 (1975).

Ludwig, U., Kahn, N., Kuhlmann, J., Mueller, W. and Zografou, C , Chem. Abstr. j*6, 144658 (1977). Kristmann, M., Cem. Conor. Res. ^, 93 (1978). Belov, N. V. and Boikova, A. I., Tsement (9), 10 (1978). Ghose, A. and Barnes, P., Cem. Conor. Res. _9, 747 (1979). Paniashvili, V. I., Yudovich, B. E. and Malinin, Yu. S., Chem. Abstr. £6, 20991 (1977). Wojnarovits, L. and Udvardi, M., Epitoanyag 25, 162 (1976). Volkonskii, B. V., Sudakas, L. G. and Kraplya, A. F., Ceram. Abstr. 5*6, 3 (1977). Par la Commission chimique du CETIC, Cim., Betons, Plâtres, Chaux 713, 205 (1978). Chromy, S., Silikaty 22, 229 (1978). Cieslinski, W., Cem. -Wapno-Gips j£, 285 (1978). Sudakas, L. G., Kraplya, A. F., Sychev, M. M., Sverdlev, L. L., Zhmodikova, M. S. and Vasil'eva, L. B., Izv. Akad. Nauk SSSR, Neorg. Mater. J_3, 2103 (1977). Grattan-Bellew, P. E., Quinn, E. G. and Sereda, P. J., Cem. Conor. Res. £, 333 (1978).

778 38. 39. 40. 41. 42. 43. 44. 45.

46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71a. 71b. 72. 73. 74. 75. 76. 77. 78.

L. Ben-Dor Malinin, Yu. S., Kravchenko, V. V., Yudovich, B. E., Dimitrieva, V. A. and Papiashvili, U. I., Chem. Abavr. _89, 94103 (1978). Abakumov, A. V., Savel'ev, V. G. and Keshishyan, T. N., Chem. Abstr. 89, 151451 (1978). Maki, I. and Chromy, S., Cemento 75_9 247 (1978). Gouda, G. R., Scanning Eleotr. Miorosc. J_, 387 (1979). Gouda, G. R., Cem. Conor. Res. 9_, 209 Ô979). Chatterjee, A. K. , Cem. Teohnol. J_0, 127, 131, 165, 171 (1979). Regourd, M. in Cement Production and \Jse> ed. J. Skalny, Engineering Foundation, New Hampshire (1979), p. 41. Suzuki, K., Shibata, S. and Ito, S., Chem. Abstr. _93_, 191036 (1980).

Berger, I. and Bimberg, R., Wies. Z. Roahsoh. Architekt.

Bauw. Weimar

10 479 (1973). Sauman, Z., Silikaty 2Q_, 169 (1976). Ciach, T. D., Gillott, J. E., Swenson, E. G. and Sereda, P. J., Cem. Conor. Res. J_, 13 (1971). Daimon, M., Ueda, S. and Kondo, R., Cem. Conor. Res. j_, 391 (1971). Nestik, S. V., Butt, Yu. M., Timashev, V. V. and Kholodnyi, A. G., Ceram. Abstr. 56_, 189 (1973). Lawrence, F. V. Jr. and Young, J. F., Cem. Conor. Res. 2» 1 4 9 (1973). Berger, R. L., Lawrence, F. V. Jr. and Young, J. F., Cem. Conor. Res. 2, 479 (1973). Young, J. F., Berger, R. L. and Lawrence, F. V. Jr., Cem. Conor. Res. 2, 689 (1973). Collepardi, M., Cem. Conor. Res.· 2» 645 (1973). Morgan, D. R., Cem. Conor. Res. 2» 847 (1973). Lawrence, F. V. Jr. and Young, J. F., Cem. Conor. Res. 2» 649 (1973). McConnell, J. D. C., J. Brit. Ceram. Soo. 7£, 171 (1971). Mitsuda, T., Cem.'Conor. Res. 3_, 71 (1973). Sauman, Z., Cem. Conor. Res. J_, 645 (1971). Mori, H., Minegishi, K., Ohta, T. and Akiba, T., Ceram. Abstr. 52, 214e (1972). Young, J. F., Berger, R. L. and Breese, J., J. Amer. Ceram. Soo. 21» 394 (1974). Chiocchio, G. and Collepardi, M., Cem. Conor. Res. 4_, 753 (1974). Chiocchio, G. and Collepardi, M., Cem. Conor. Res. _4, 441 (1974). Dyczek, J. and Pétri, M., oth.ICCC, Moscow (1974). Alunno-Rossetti, V., Chiocchio, G. and Collepardi, M., Cem. Conor. Res. 4_, 279 (1974). Skalny, J., Cem. Conor. Res. 4_, 987 (1974). Alunno-Rossetti, V., Chiocchio, G. and Collepardi, M., Cem. Conor. Res. 4_, 991 (1974). Young, J. F., Powder Teohnol. £, 173 (1974). Diamond, S., Cem. Conor. Res. 2» 6 I 7 (1972). Copeland, L. E. and Verbeck, G., 6th ICCC, Moscow (1974). Marchese, B., Cem. Conor. Res. 4·, 481, 485 (1974). Marchese, B., Cemento 7J_, 23, 67 (1974). Berger, R. L., Lawrence, F. V. and Young, J. F., Cem. Conor. Res. 4_, 498 (1974). Teoreanu, I. and Muntean, M., 6th ICCC3 Moscow (1974). Javelas, R., Maso, j. C. and Ollivier, J. P., Cem. Conor. Res. 4_, 167 (1974). Locher, F. and Richartz, W., 6th ICCC, Moscow (1974). Sierra, R., 6th ICCC3 Moscow (1974). Lawrence, F. V. Jr., Reid, D. A. and DeCarvalho, A. A., J. Amer. Ceram. Soc. 27, 144 (1974). Goto, S., Daimon, M. , Hosaka, G. and Kondo, R. , J. Amer. Ceram. 22.» 2 8 ] (1976).

Electron and Optical Microscopy

779

79. Gard, J. A. and Taylor, H. F. W. , Cem. Conor. Res. _6, 667 (1976). 80. Diamond, S. in Hydraulio Cement Pastes: Their Struoture and Properties, Cem. Concr. Assoc, London (1976), p. 2. 81. Regourd, M., Hornain, H. and Mortureux, B., Cim., Betons, Plâtres, Chaux 6_93, 87 (1975). 82. Stein, H. N., Cemento J7£, 3 (1977). 83. Ménétrier, D., Ph.D. thesis, University of Dijon (France), 1977. 84. Barret, P., Ménétrier, D. and Bartrandie, D., Chem. Abstr. 8£, 11016 (1977). 85. Kalousek, G. L., Mitsuda, T. and Taylor, H. F. W. , Cem. Conor. Res. ]_, 305 (1977). 86. Danyushevskii, V. S. and Dzhabarov, K. A., Izv. Akad. Nauk SSSR Neorg. Mater. _Γ3, 1289 (1977). 87. Stucke, M. S. and Majumdar, A. J., Cem. Conor. Res. ]_, 711 (1977). 88. Collepardi, M. and Marchese, B., Cem. Conor. Res. _2, 57 (1972). 89. Berger, R. L., Young, J. F. and Lawrence, F. V., Cem. Conor. Res. _2, 633 (1972). 90. Odler, I. and Skalny, J., J. Amer. Ceram. Soo. 54, 362 (1971). 91. Traetteberg, A. and Ramachandren, V. S., J. AvpTT Chem. Bioteohnol. 24, 157 (1974). 92. Traetteberg, A., Ramachandran, V. S. and Grattan-Bellew, P. E., Cem. Conor. Res. 4_, 203 (1974). 93. Collepardi, M., Marcialis, A. and Vincenzu, S., Cemento 7£, 83 (1973). 94. Ben-Dor, L. and Perez, D., J. Mater. Soi. JJ_, 239 (1976). 95. Berger, R. L., Kung, J. H. and Young, J. F., J. Testing Evaln. 4_, 85 (1976). 96. Singh, N. B. and Ojha, P. N., J. Mater. Soi. Jj>, 2675 (1981). 97. Young, J. F. and Tong, H-S., Cem. Conor. Res. ]_, 627 (1977). 4 98. Lawrence, F. V., Young, J. F. and Berger," R. L., Cem. Conor. Res. 7_, 369 (1977). 99. Marchese, B., Cemento 73, 195 (1976); Cem. Conor. Res. ]_, 9 (1977).

100.

101. 102. 103. 104. 105. 106. 107. 108. 109. 110.

Marchese, B . , J.

Amer.

Cem.

8_9 733 (1978).

Cerarrt. Soo.

_60, 459 ( 1 9 7 7 ) .

Goto, S., Daimon, M., Hosaka, G. and Kondo, R., J. Amer. Ceram. Soo. j)0, 461 (1977). Bobrov, B. S. and, H i n , V. I., Chem. Abstr. 87_, 72457 (1977). Efes, Y., Chem. Abstr. £6, 144693 (1977). Kurczyk, H. G., Chem. Abstr. 8£, 160085 (1977). Nikonova, N. S. and Timashev, V. V., Chem. Abstr. 8(6, 194002 (1977). Stevula, L. and Petrovic, J., Cem. Conor. Res. JJ_, 183 (1987). Young, J. F., Tong, H. S. and Berger, R. L., J. Amer. Ceram. Soo. 6£, 193 (1977). Krzywoblocka-Laurow, R. and Zielinska, E., Cem.Wapno-Gips 32, 80 (1978). Jelenic, I., Bezjak, A. and Bujan, M., Cem. Conor. Res/ _8, 173 (1978). Dent Glasser, L. S., Lachowski, E. E., Mohan, K. and Taylor, H. F. W. , Conor.

Res.

Hannawayya, F., Mater. Soi. Eng. _34, 183 (1978). Dobronravora, L. A., Butt, Y. M. , Kolbasov, V. M. and Sazonova, L. A., Chem. Abstr. _89, 134528 (1978). 113. Harada, T., Ohta, M. and Tagaki, S., Chem. Abstr. _88, 196407 (1978). 114. Valenti, G. L., Sabatelli, V., Ann. Chim. (Rome) J56, 551 (1976); ibid., 68_, 7 (1978). 115. Valenti, G. L., Sabatelli, V. and Marchese, B., Cem. Conor. Res. 8_, 61 (1978). 116. Drzaj, B., Hocevar, S., Slokan, M. and Zajc, A., Cem. Conor. Res. 8_, 711 (1978). 117. Bentur, A., Milestone, N. B. and Young, J. F., Cem. Conor. Res. 8, 7 21 (1978). 118. Hedin, R. , Chem. Abstr. 8_8, 11040 (1978).

111. 112.

780 119. 120. 121. 122. 123. 124. 125. 126. 127. 128. 129. 130. 131. 132. 133. 134. 135. 136. 137. 138. 139. 140. 141. 142. 143. 144. 145. 146. 147. 148. 149. 150. 151. 152. 153. 154. 155. 156.

L. Ben-Dor Shchurov, A. F., Ershova, T. A., Danyushevskii, V. S. and Dzhabarov, K. A., Izv. Akad. Nauk SSSR, Neorg. Mater. _T4, 569 (1978). Aiitonicheva, N. B., Balkevich, L. V., Leonov, I. I. and Timashev, V. V., Chem. Abstr. 89_, 134530 (1978). Marchese, B., J. Amer. Ceram. Soo. 6J_, 349 (1978). Bentur, A., Berger, R. L., Lawrence, F. V. Jr., Milestone, N. B., Mindess, S. and Young, J. F., Cem. Conor. Res. £, 83 (1979). Chatterji, S., Cem. Conor. Res. _9, 655 (1979). Bentur, A., Berger, R. L., Lawrence, F. V. Jr., Milestone, N. B., Mindess, S. and Young, J. F., Cem. Conor. Res. j>> 657 (1979). Bentur, A., Milestone, N. B., Young, J. F. and Mindess, S., Cem. Conor. Res. 9_. 161 (1979). Ben-Dor, L. and Rubinsztain, Y., J. Mater. Soi. _U, 365 (1979). Milestone, N. B., J. Amer. Ceram. Soo. 62_y 321 (1979). Abo-El-Enein, S. A. and Mikhail, R. Sh., J. Chem. Teohnol. Bioteohnol. _29, 629 (1979). Bukowski, J. M. and Berger, R. L., Cem. Conor. Res. _9, 57 (1979). Berger, R. L., Cem. Conor. Res. _9, 649 (1979). Goodbrake, C. J., Young, J. F. and Berger, R. L., J. Amer. Ceram. Soo. 62, 168 (1979). Menetrier, D., Jawed, I., Sun, T. S. and Skalny, J., Cem. Conor. Res. 2, 473 (1979). Menetrier, D., McNamara, D. K., Jawed, I. and Skalny, J., Cem. Conor. Res. 2J), 107 (1980). Menetrier, D., Jawed, I., Sun, T. S. and Skalny, J., Cem. Conor. Res. _K), 425 (1980). Menetrier, D., Jawed, I. and Skalny, J., Cem. Conor. Res. jjO, 697 (1980). Diamond, S. and Lachowsky, E.E., Cem. Conor. Res. JMO, 703 (1980). Taylor, H. F. W. in Cement Production and Use, ed. J. Skalny, Eng. Foundation, New Hampshire (1979), p. 107; Proo. Brit. Ceram. Soo. (28), 147 (1979). Diamond, S., Cem. Conor. Res. £, 413 (1976). Stucke, M. S. and Majumdar, A. J., in Portland Cement Pastes - Their Structure and Properties3 Cem. & Concr. Assoc, Slough, U.K. (1976), p. 31. Stucke, M. S. and Majumdar, A. J., Cem. Conor. Res. £, 515 (1979). Gard, J. A., Mohan, K. and Taylor, H. F. W., J. Amer. Ceram. Soo., 63_, 336 (1980). Tashiro, C. Okuni, K. and Mino, K., Chem. Abstr. _93, 191040 (1980). Fujii, K. and Kondo, W., J. Amer. Ceram. Soo. 62., 161 (1979). Suzuki, Y., Ogawa, K. and Hishiyama, K., Chem. Abstr. ^3., 191035 (1980). Urano, T. and Sumiyoshi, Y., Ceram. Abstr. .54, 191 (1971). Ciach, T. D. and Swenson, E. G., Cem. Concr. Res. ±, 143, 159, 257, 367, 515 (1971). Gupta, P., Chatterji, S. and Jeffery, J. W., Chem. Teohnol. jl_, 59 (1970); 2» 19, 146 (1972); _4, 146 (1973). Ramachandran, V. S. and Feldman, R. F., Cem. Conor. Res. }_, 729 (1973). Mehta, P. K. and Lesnikoff, G., J. Amer. Ceram. Soo. 5A_, 210 (1971). Ramachandran, V. S. and Feldman, R. F., J. Appl. Chem. Bioteohnol. Z3, 625 (1973). Ramachandran, V. S. and Feldman, R. F., Cem. Concr. Res. 3, 41 (1973). Diamond, S., J. Amer. Ceram. Soc. _56_, 323 (1973). Kozyreva, N. A., Butt, Yu. M. and Kolbasov, V. M., Ceram. Abstr. 5β_9 165h, j (1973). Cottin, B., Cem. Concr. Res. J_, 177, 273 (1971). Midgley, H. B. and Pettifer, K., Trans. J. Brit. Ceram. Soo. 7_1_, 55 (1972). Sauman, Z. and Lach, V., Cem. Conor. Res. 2_, 435 (1972).

Electron and Optical Microscopy 157. 158. 159. 160. 161. 162. 163. 164. 165. 166. 167. 168. 169. 170. 171. 172. 173. 174. 175. 176. 177. 178. 179. 180. 181. 182. 183. 184. 185. 186. 187. 188a. 188b. 188c. 189. 190. 191. 192. 193. 194. 195. 196. 197. 198. 199. 200. 201.

781

Choi, S. H. and Han, S. M., Ceram. Abstr. _5£, 242 i (1973). Grandet, J. and Ollivier, J. P., Cem. Conor. Res. ±Q_9 759 (1980). Uchikawa, H. and Uchida, S., Cem. Conor. Res. 2_, 681 (1972). Uchikawa, H. and Uchida, S., Cem. Conor. Res. J3> 607 (1973). Butt, Yu. M., Beton Zhelezobeton JJ_, 9 (1974). Frost Resistance of Concrete, Netherlands, C.U.R. Report 64 (1974). Revay, M., 6th ICCC, Moscow (1974). Traetteberg, A. and Sereda, P. J., 6th ICCC, Moscow (1974). Traetteberg, A. and Grat tan-Be Hew, P. E., J. Amer. Ceram. Soc. _58, 221 (1975). Breval, E., Summaries of Contributions to a Seminar in Koge, Denmark. Gouda, G R. and Roy, D. M., Cem. Conor. Res. _5> 551 (1975). Mehta, P. K., Cem. Conor. Res. j6, 169 (1976). Hansen, W. C , Cem. Conor. Res. 6>, 595 (1976). Mehta, P. K., Cem. Conor. Res. <6, 597 (1976). Chatterji, S., Cem. Conor. Res. £, 711 (1976). Mehta, P. K. , Cem. Conor. Res. _6, 713 (1976). Kurdowski, W. and Thiel, A., Cem. Conor. Res. U_9 29 (1981). Chou, K. S. and Burnet, G., Cem. Conor. Res. JJ_, 57 (1981). Ramachandran, V. S. and Beaudoin, J. J., J. Mater. Sei. jj_, 1893 (1976). Breval, E., Cem. Conor. Res. _6, 129 (1976). Hansen, W. C. , Cem. Conor. Res. 6_, 819 (1976). Breval, E., Cem. Conor. Res. £,819 (1976). Bradbury, C , Callaway, P. M. and Double, D. D., Mater. Sei. Eng. ^23, 43 (1976). Traetteberg, A. and Sereda, P. J., Cem. Conor. Res. _6, 41 (1976). Regourd, M., Hornain, H. and Mortureux, B., Cim., Betons, Plâtres,, Chaux. 68T7, 69 (1974). Regourd, M., Hornain, H. and Mortureux, B., Cem. Conor. Res. _6, 733 (1976). Breval, E., Cem. Conor. Res. ]_, 297 (1977). Tech. Rpt., F.L. Smidth Labs., Copenhagen (1977). Reaction of AVuminates during the Settling of Cement, éd. H. N. Stein, CEMBUREAU, Paris, 1977, Seminar in Eindhoven (Netherlands). Skalny, J. and Tadros, M. E., J. Amer. Ceram. Soc. 60, 174 (1977). Ballard, W. V. and Day, D. E., Amer. Ceram. Soc. BuTZ. 5]_9 660 (1978); Winstrom, K. W. and Day, D. E., Amer. Ceram. Soc. Bull. ^57, 680 (1978). Andreeva, E. P. and Sanzhaasuren, R., Chem. Abstr. £7, 156219 (1977). Sanzhaasuren, R., Andreeva, E. P. and Burova, D. K., Chem. Abstr. &]_, 72465 (1977). Stukalova, N. P. and Andreeva, E. P., Chem. Abstr. _87, 72466 (1977). Klyusov, A. A., Lepnev, E. N., Bakshutov, V. S., Ilyukhin, V. V. and Nikitin, V. N., Izv. Ahad. Nauk SSSR, Neorg. Mater. Jjj», 2070 (1977). Krzywoblocka-Laurow, R. and Zielinska, E., Cem.-Wapno-Gips 30, 372 (1976). Krzywoblocka-Laurow, R. and Zielinska, E., Cem.-Wapno-Gips 32., 206 (1978). Tinnea, J. and Young, J. F., J. Amer. Ceram. Soc. £0, 387 (1977). Sudoh, G. Akiba, T. and Iwasaki, T., Rev. 30th Gen. Mtg. Cem. Assoc. Japan (Engl. Abstr.), p. 42 (1976). Tashiro, C. and Oba, J., Cem. Conor. Res. _9, 253 (1979). Tashiro, C , Oba, J. and Akama, K., Cem. Conor. Res. 2» 303 (1979). Bensted, J. Cem. Conor. Res. 10, 110 (1980). Tashiro, C. Oba, J. and Akama, K., Cem. Conor. Res. 10, 121 (1980). Akama, K. and Oba, J., Chem. Abstr. 93,, 191039 (198077 Breval, E., J. Amer. Ceram. Soc. J32, 395 (1979). Sakai, E., Raina, K., Asaga, K., Goto, S. and Kondo, R., Cem. Conor. Res. J_0, 311 (1980). Lorprayoon, V. and Rossington, D. R., Cem. Conor. Res. JJ_, 267 (1981).

782 202. 203. 204. 205. 206. 207. 208. 209. 210. 211. 212. 213. 214. 215. 216. 217. 218. 219. 220. 221. 222. 223. 224. 225. 226. 227. 228. 229. 230. 231. 232. 233. 234. 235. 236. 237. 238. 239. 240. 241. 242.

L. Ben-Dor Somiya, S., Yoshimura, M., Yamazaki, K. and Nakano, Y., Chem. Abstr. 93, 136900 (1980). Weisweiler, W. and Ahmed, S. J., Zem.-Kalk-Gips 13» 84 (1980). Tsuyuki, N., Sugano, M., Ito, T. and Kasai, J., Chem. Abstr. 89, 66171 (1978). Marchese, B., Masolo, G. and Sersale, R., J. Amer. Ceram. Soo. 55, 146 — (1972). Mehta, P. K., Cem. Conor. Res. 3^» 1 (1973). Mehta, P. K. , J. Amer. Ceram. Soo. 56_, 315 (1973). Mather, B., Cem. Conor. Res. 3, 651 (1973). Hansen, W. C , Cem. Conor. Res. 3_, 655 (1973). Mehta, P. K., Cem. Conor. Res. jS, 653, 657 (1973). Satava, V. and Veprek, 0., J. Amer. Ceram. Soo. _5£, 357 (1975). Skoblinska, N. N. and Krasilnikov, K. G., Cem. Conor. Res. _5, 381 (1975); Skoblinksa, N. N., Krasilnikov, K. G., Niktina, L. V. and Varlamov, V. P. Cem. Conor. Res. _5> 419 (1975). Sycheva, L. I., Timashev, V. V. and Butt, Y. M., Ceram. Abstr. 56_, 53 (1977). Marchi, M., Chem. Abstr. 93_, 202910 (1980). Spit, J. and van der Knapp, S. C., Klei Keram. _20, 331 (1970). Gorelova, I. L., Lyubimova, T. Yu., Bykov, M. V. and Mikhailov, N. V., Dokl. Akad. Nauk SSSR 199, 883 (1971). Chat ter ji, S., Trans. J. Brit. Ceram. Soo. _70> 195 (1971). Volzhenskii, A. V. and Chistov, Yu. D., Tsemenv (7) 9 (1971). Williamson, R. B., Frog. Mater. Soi. JL5, 189 (1972). Gyula, Z., Epitoanyag 23, 281 (1971). Regourd, M. and Hornain, H., Rev. Mater. Constr. 693, 73 (1975). Regourd, îi., Cim., Betons, Plâtres, Chaux (692) 9 (1975). Grudemo, Ä., 6th TCCC, Moscou) (1974). Copeland, L. E. and Verbeck, G., 6th TCCC, Moscow (1974). Hedin, R., 6th TCCC, Moscow (1974). Kondo, R. and Daimon, M., 6th TCCC, Moscow (1974). Mori, H., Sudoh, G., Minegishi, K. and Uhta, T., 6th TCCC, Moscow (1974). Feldman, R. F. and Beaudoin, J. J., 6th TCCC, Moscow (1974). Mironov, S. A., Larionova, Z. M. and Garashin, V. P., Tsement 73^ 18 (1974). Lach, V. and Bures, J., 6th TCCC, Moscow (1974). Jambor, J., 6th TCCC, Moscow (1974). Jambor, J. and Zivica, V., Cem. Res. Progress 1975, Chap. 2, 16 (1976). Jambor, J. in Hydraulic Cement Pastes: Their Structure and Properties, Cem. Concr. Assoc, London (1976), p. 175. Theisen, K. and Johansen, V., Amer. Ceram. Soc. Bull. _54., 787, 791 (1975). Setzer, M. J., Zement u. Beton 85/86, 29 (1975). Matkovic, B. and Young, J. F., Cement (Yugoslavia) \]_, 119, 185 (1973/4). Nussbaum, P. J., Kantro, D. L. and Helmuth, R. A., Draft Rpt. DOT-FH-118129, Fed. Kwy. Admin. U.S. Dept. Transp., Washington, D.C. (August 1975). Venuat, M. and Tran-Thanb-Phat, M., Cim., Betons, Platines, Chaux 693, 99 (1975). Hornain, H. in J. Alexandre, Rate of Carbonation, RILEM Mtg. Carbonation of Concrete, England, April (1976). Sudakas, L. G., Tsement (7), 7 (1977). Volkonskii, B. V., Sudakas, L. G. and Kraplya, A. F., Chem. Abstr. 9\_9 26117 (1979). Taylor, D. H., J. Testing- Evaln. 5>, 102 (1977).

Electron and Optical Microscopy 243. 244. 245. 246. 247. 248. 249. 250. 251. 252. 253. 254. 255. 256. 257. 258. 259. 260. 261. 262. 263. 264. 265. 266. 267. 268. 269. 270. 271. 272." 273. 274. 275. 276. 277. 278. 279. 280. 281. 282. 283. 284. 285.

783

Danyushevskii, V. S. and Dzhabarov, K. A., Chem. Abstr. _86, 94927 (1977). Barnes, P., Moore, N. T. and Sarkar, S. L., Ind. Conor. J. 5J_, 181 (1977). Lyuttsau, V. G., Parygin, V. P. and Shtein, L. M., Izv. Akad. Nauk SSSR, Neorg. Mater. J_3, 1078 (1977). Malinin, Yu. S., Papiashvili, U. I. and Yudovich, B. E., Dokl. Akad. Nauk SSSR 233, 653 (1977). Groves, G. W., J. Mater. Soi. \6_, 1063 (1981). Feldman, R. F. and Beaudoin, J. J., Cem. Conor. Res. _6, 389 (1976). Taylor, H. F. W., Cem. Conor. Res. ]_, 465 (1977). Feldman, R. F. and Beaudoin, J. J., Cem. Conor. Res. 1_, 469 (1977). Schneider, V. and Weiss, R., Cem. Conor. Res. 1_, 259 (1977). Tashiro, C. and Urushima, H., Rev. 30th Gen. Mtg. Cem. Assoo. Japan (English. Abstr.) 36 (1976). Sylla, H. M. , Zem. -Kalk-Gips 3JD, 487 (1977). Kittl, P. and Castro, J., Chem. Abstr. 8_8, 54256 (1978). Rune, H., Chem. Abstr. £8, 11040 (1978). Timashev, V. V., Tsement (2), 6 (1978). Sereda, P. J., Epitoanyag 30, 147 (1978). Rosova, M. and Tichomirov, V., Chem. Abstr. _92, 10302 (1980). Drescher, E., Chem. Abstr. 9J_, 127935 (1979). Chatterji, S., Amer. Ceram. Soo. Bull. _58_, 233 (1979). Sugi, T., Kataoka, K., Yanagihara, H. and Ando, Y., Chem. Abstr. ^93, 209253 (1980). Diamond, S., Hwy. Res. Brd., Speo. Rpt. 127 (1972). Kittl, P. and Castro, J. H., Mater. Constr. JL58, 81 (1975). Gebauer, J. and Harnik, A. B., Cem. Conor. Res. 5_, 163 (1975). Marchese, B., Cem. Conor. Res. _K), 861 (1980). Cole, W. F., Lancucki, C. J. and Sandy, M. J.., Cem. Conor. Res. jj_, 443 (1981). Sauman, Z., Cem. Conor. Res. _2> 54Γ (1972). Fataliev, S. A. and Imanov, A. M., Ceram. Abstr. 51_t 144a (1974). Mueller, H., Ridemueller, G. and Schaighofer, B., Chem. Abstr. J35, 98446 (1976). Shpynova, L. G., Tuzyak, V. E., Nikonets, I. I. and Feklin, V. I., Chem. Abstr. 93^, 136832 (1980). Ramachandran, V. S. in Caloium Chloride in Conorete-Soienoe and Technology, Appl. Sei. Pub., U.K. (1976). Ramachandran, V. S. and Feldman, R. F., Cemento 75, 311 (1978). Midgley, H. G. and Pettifer, K., Cem. Conor. Res. J_, 101 (1971). Takagi, S., Yamaguchi, G. and Saito, M., Chem. Abstr. 83_, 102427 (1975). Tashiro, C. and Kubota, W., Cem. Conor. Res. _6, 727 (1976). Hachemi, A. A., Murat, M. and Cubaud, J. C., Cim., Betons, Plâtres, Chaux 7£2, 285 (1976). Kawadkar, K. G. and Krishnamoorthy, S., Cem. Conor. Res. JJ_, 103 (1981). Isagar, J., 6th ICCC, Moscow (1974). Isogai, J. and Kondo, R., Chem. Abstr. £6, 126001 (1977). Regourd, M., in The Action of Sea-Water on Cements, lTInst. Tech. de Bâtiment et de Travaux Publics, No. 329 (1975). Peltier, R., in The Behavior of Cement in Sea Water, Cim. Chaux 21 (Jan. 1976). Figg, J., Moore, A. E. and Gutteridge, W. A., Cem. Conor. Res. _6, 691 0976). Teoreanu, I., Onea, I., Hriscu, C , Bucea, L., Banescu, R. and Stamate, I., Bull. Inst. Politeh nGheorghe Gheorghiu-Dej", Ser. Chim. - Metal. j[9_, 47 (1977). Teramoto, H. and Koie, S., J. Amer. Ceram. Soo. J?9, 522 (1976). Teoreanu, I., Cim., Betons, Plâtres, Chaux 101_9 228 (1977).

784 286. 287. 288. 289. 290. 291. 292. 293. 294. 295. 296. 297. 298. 299. 300. 301. 302. 303. 304. 305. 306. 307. 308. 309. 310. 311. 312. 313. 314. 315. 316. 317. 318. 319. 320. 321. 322. 323. 324.

L. Ben-Dor Thomas, N.L., Jameson, Ώ. A. and Double, D. D., Cem. Conor. Res. 11, 143 (1981). Alford, N. McN., Rahman, A. A. and Salih, N., Cem. Conor. Res. U_, 235 (1981). Komar, A. G., Sulimenko, L. M., Anin, Yu. M. and Koketkina, A. I., J. Appl. Chem. USSR _49, 797 (1976). Locher, F. W., Richartz, W. and Sprung, S., Zem.-Kalk-Gips 29, 435 (1976). Paillere, A. M. and Gonzalez, J. C., Bull. Liaison Labs. Fonts. Chaussées 9J_, 17 (1977). Moldovan, V., Chem. Abstr. _86, 110428 (1977). Shimoda, M., Chem. Abstr. 8£, 46471 (1977). Mori, S., Shimoda, M. and Kasai, J., Ceram. Abstr. .57, 85 (1974). Suleimanov, F. G., Chem. Abstr. 8]_, 72473 (1977). Khalil, S. M. and Ward, M. A., Mater. Constr. (Paris) \0_9 67 (1977). Chebotnikov, V. L. and Shalinets, A. B., Chem. Abstr. 8]_, 121843 (1977). Ward, M. A. and Morgan, D. R., Epitoanyag 24, 329 (1972). Collepardi, M. and Massidda, L., in HydrauTtc Cement Pastes: Their Structure and Properties, Cem. Concr. Assoc, London (1976), p. 256. Takagi, S., Chem. Abstr. 93_» 209225 (1980). Diamond, S. and Gomez-Toledo, C., Cemento 75, 189 (1978). Odler, I., Schönfeld, R. and Dörr, H., Cem. Conor. Res. 18, 525 (1978). Roy, D. M., Gouda, G. R. and Bobrowsky, A., Cem. Conor. Res. _2, 349 (1972). Gouda, G. R. and Roy, D. M., J. Amer. Ceram. Soo. .59, 412 (1976). Sarkar, A. K. and Roy, D. M ., Bull. Amer. Ceram. Soo. _56, 984 (1977). Abo-El-Enein, S. A., Gabor, N. A. and Mikhail, R. Sh., Cem. Conor. Res. _7, 231 (1977). Abo-El-Enein, S. A., Gabor,-N. A. and Mikhail/ R. Sh., Cem. Conor. Res. 1_, 363 (1977). Butt, Yu. M., Beton Zhelezobeton JJ_, 9 (1974). Sudoh, G., Akiba, T. and Arai, K., Chem. Abstr. 8tf 84023 (1975). Sudoh. G., Akiba, T. and Arai, K., Rev. 28th Gen. Mtg. Cem. Assoc, Japan, p. 44 (1979). Kayyali, 0. A., Page, C. L. and Ritchie, A. G. B., in Hydraulic Cemenv Pastes: Their Structure and Properties, Cem. Concr. Assoc, London (1976), p. 204. Chandra, S., Hedberg, B. and Berntsson, L., Cem. Concr. Res. JJ3, 467 (1980). Uchikawa, H. and Tsukiyama, K., Cem. Concr. Res. 3_, 263 (1973). Uchikawa, H. and Uchida, S., J. Res. Onoda Cem. Co. _26, 1 (1974). Uchikawa, H. and Tsukiyama, K., Chem. Abstr. _83, 84008 (1975). Skomorovsky, E., 6th ICCC, Moscow (1974). Uchikawa, H., Uchida, S. and Mihara, Y., Cemento 75, 59 (1978). Walsh, D., Ootoni, M. A., Taylor, M. E. and Marcinkowski, M. J., J. Mater. Soi. £, 423 (1974). Zilosani, Z. N. and Sakvarelidze, A. V., 6th ICCC, Moscow (1974). Barnes, B. D.. Ph.D. Thesis, Purdue University, West Lafayette, Indiana (1975). Hadley, D. W., Ph.D. Thesis, Purdue University, West Lafayette, Indiana (1972). Javelas, R., Maso, J. C., Ollivier, J. P. and Thenoz, B., Cem. Concr. Res. J5, 285 (1975). Grudemo, A., Swedish Cem. Concr. Res. Inst., CBI Rpt. 9:75, 27 pp. (1975). Diamond, S., Cem. Concr. Res. 6, 549 (1976). Barnes, B. D., in Morphology of the Paste-Aggregate Interface, Purdue Univ., Hwy. Res. Prog. JHRP, Rpt. 76-13 (1976).

Electron and Optical Microscopy 325. 326. 327. 328. 329. 330. 331. 332. 333. 334. 335. 336. 337. 338. 339. 340. 341. 342. 346. 344. 345. 346. 347. 348. 349. 350. 351. 352. 353. 354. 355. 356. 357. 358. 359. 360. 361.

785

Barnes, B. D. and Diamond, S., Proo. 2nd Conf, Mech, Behav. Mater, 1414 (1976). Barnes, B. D., Diamond, S. and Dolch, W. L., Cem, Conor, Res. _8, 233, 263 (1978). Barnes, B. D., Diamond, S. and Dolch, W. L., J. Amer, Ceram. Soo, _6_2, 21 (1979). Marchese, B., Cem, Conor, Res, £, 519 (1979). Walker, H. N., Cem. Conor, Res, _9, 525 (1979). Barnes, B. D. , Diamond, S. and Dolch, W. L., Cem, Conor. Res, 9_, 523, 527 (1979). Tait, R. B. and Garrett, G. G., Chem. Abstr, 8£, 157402 (1978). Belov, N. V., Papiashvili, U. I. and Yudovich, B. E., Proo, 9th Int, Cong, Eleo, Mioroso, J_» 484 (1978). Garrett, G. G., Jennings, H. M. and Tait, R. B. , J. Mater, Soi, _U, 296 (1979). Mindess, S. and Diamond, S., Cem, Conor. Res. \0_, 509 (1980). Mehta, P. K. and Polivka, M., 6th ICCC, Mosoow (1974). Miyake, N., Nakagawa, K. and Isogai, J., Rev. 29th Gen. Mtg. Cem. Assoo. Japan, 82_ (1975). Sato, M., Okura, R., Sasaki, M., Miyazawa, Y. and Sato, S., Rev. 29th Gen. Mtg. Cem. Assoo. Japan 80 (1975). El-Didamony, H., Haggag, M. Y. and Abo-El-Eneim, S. A., Cem. Conor. Res. 81, 351 (1978). Hanafi, S., Abo-El-Eneim, S. A., Mikhail, R. S., Good, R. J. and Irani, J., Cemento 76, 189 (1979). Ohta, T., Yokoyama, S. and Sakamoto, K., Rev. Gen. Mtg. Teoh. Sess., 33rd Chem, Assoo, Japan 75_ (1979). Double, D. D. and Hellawell, A., Nature 261, 486 (1976). Sherwood Taylor, F., in Inorganio and Theoretical Chemistry, 8th edi-tion, Heinemann, London (1948). Double, D. D. and Hellawell, A., Soi, Amer. 23Ί_, 82 (1977). Powers, T. C , J. Portland Cem. Ass. Rev. Dev. Labs \ 47 (1961). Double, D. D., Hellawell, A. and Perry, S. J., Proo. Roy. Soo. (London) A 359 435 (1978). Double, D. D., Silic. Ind. JJ_, 233 (1978). Jennings, H. M. and Pratt, P. L., Annual Mtg. British Ceram. Soc. (London), Dec. 1978; Proo. Brit. Ceram. Soo. (28), 179 (1979). Jennings, H. M. and Pratt, P. L., Cem. Conor. Res. £ , 501 (1979). Jennings, H. M. and Pratt, P. L., J. Mater. Soi. J_5, 250 (1980). Birchall, J. D., Howard, A. J. and Bailey, J. E., Proo. Roy. Soo. (London) A 360, 445 (1978). Bailey, J. E. and Chescoe, D., Proo. Brit. Ceram. Soo. (28), 165 (1979). Barnes, P., Ghose, A. and Mackay, A. L., Cem. Conor. Res, _K), 639 (1980). Coatman, R. D., Thoman, N. L. and Double, D. D., J, Mater. Soi, _1_5 2017 (1980). Birchall, J. D., "The Hydration of Portland Cement", informal symposium, Oxford, England (March 1980), Cem. Conor. Res. JJD, 869 (1980). Regourd, M., Ann. Chim. (Paris) 4_, 179 (1979). Satarin, V. I., 6th ICCC, Mosoow (1974). Mikhail, R. Sh., Mourad, W. E. and Gouda, V. K., Cem. Conor. Res. 4_, 807 (1974). Kravshenko, I. V., '6th ICCC, Moscow (1974). Mori, S., Uchikawa, H., Tsukeyama, K. and Uchida, S., 6th ICCC, Moscow, (1974). Regourd, R., Hornain, H. and Mortureux, B., Cim,, Betons, Plâtres, Chaux 699, 83 (1976). Sersale, R., Aiello, R., Colella, C. and Frigione, G., Silic. Ind. 4j_, 513 (1976).

786 362. 363. 364. 365. 366. 367. 368. 369. 370.

371. 372. 373. 374. 375. 376. 377. 378. 379. 380. 381. 382. 383. 384. 385. 386. 387. 388. 389. 390. 391. 392. 393. 394. 395. 396. 397. 398. 399. 400. 401. 402. 403. 404.

L. Ben-Dor Regourd, M., Hornain, H. and Mortureux, B., Silio. Ind. 4_2, 19 (1977) Marchese, B. and Sersale, R., Cemento _75_, 253 (1978). Massida, L. and Sanna, U., Cem, Conor. Res. 9_t 127 (1979). Tashiro, C. and Okubo, Y., Gypsum-Lïme jjrô, 95 (1980). Tashiro, C., Urushima, H. and Yatagai, K., Chem. Abstr. 89_, 151461 (1978). Kondo, R., Daimon, M., Song, C.-T. et al. Λ Amer. Ceram. Soc. Bull. 5_9, 848 (1980). Gebauer, J. and Coughlin, R. W., Cem. Conor, Res, l, 187 (1971). Lyk'yanovich, V. M. and Kolyutskii, U. N., Zhur. fïz. Khim. _48, 2131 (1974). Steinberg, M., Dikeon, J. T., Kukacka, L. E., Backstrom, J. E., Colombo, P., Hickey, K. B., Auskern, A., Rubenstein, S., Manowitz, B. and Jones, C. W., Brookhaven Natl. Lab. Rpt. No. BNL-50218 (T-560) & USBR Gen. Rpt. REC-OCE-70-1 (1969). Auskern, A. and Horn, W., in Polymers in Concrete, Amer. Concr. Inst. Spec. Pub. SP-40, 223 (1973). Lach, V., Knazeva, V. P. and Merking, A. P., Stavivo _54, 18 (1976). Mel'nik, M. V., Chem. Abstr. _85, 129465 (1976). Isenburg, J. E. and Vanderhoff, J. W., J. Amer. Ceram. Soo. _57_, 242 (1974). Suleimanov, F. G., Chem. Abstr. _87, 72473 (1977). Cherkinski, Yu. S. and Slipshenko, G. F., Chem. Abstr. 86, 144653 (1977). Ball, M. C. and Tomkins, D. W., Cem. Conor. Res. 2» 215 (1977). Matsumoto, T., Sakai, I. and Egawa, T., Chem. Absvr. _88_, 54254 (1978). Narayan Swamy, R., J. Mater. Soi. _U, 1521 (1979). Wilson, A. D. , Brit. Polymer J. 6_, 165 (1974). Cowie, J. M. G. and Haq, Z., Polymer j_9, 1052 (1978). Barry, T. I., Clinton, D. J. and Wilson, A. D. , J. Dent. Res. 58.» 1072 (1979). Kent, B. E., Lewis, B. G. and Wilson, A. D. , J. Dent. Res. J58_, 1607 (1979). Opoczky, L. and Bocs, A., Epitoanyag 24, 1 (1972). Opoczky, L., Mechler, I. and Szatura, L., Epitoanyag ]A_t 121 (1972). Murât, M., Cem. Conor. Res. _4, 327 (1974). Mah, M. and Boatman, E. S., Scanning Elect. Miorosc. J_, 85 (1978). Pinchin, D. J. and Tabor, D., Cem. Conor. Res. _8, 15 (1978). Al Khalaf, M. N. and Page, C. L., Cem. Conor. Res. _9> 197 (1979). Mikhail, R. Sh., El-Khalik, Abd., Hassanein, A., Dollimore, D. and Stino, R., Cem. Conor. Res. _8, 765 (1978). Mikahil, R. Sh., Dollimore, D. and Stino, R. , Cemento _75_, 277 (1978). DeVekey, R. C. and Majumdar, A. J., J. Mater. Soi. 5_, 183 (1970). Majumdar, A. J., Cem. Conor. Res. 4_, 247 (1974). Aleszka, J. and Schnittgrund, G., U.S. Army Constr. Eng. Res. Lab. Tech. Rpt. M-122, 69 pp (1975). Velpari.V., Ramachandran, B. E., Bhaskaran, T. A., Pai, B. C. and Balasubramanian, N., J. Mater. Soi. _1_5, 1579 (1980). Litherland, K. L. , 0-akley, D. R. and Proctor, B. A., Cem. Conor. Res. _Π_, 455 (1981). Mills, R. H., Cem. Concr. Res. JJ_, 421 (1981). Saji, K., Zem.-Kalk-Gips _T2> 418 (1959). Kovacs, R. , Epitoanyag 23_, 180 (1971). Kokubu, M. and Yamada, J., 6th ICCC, Moscow (1974). Entin, Z. B., Yashina, E. T., Lepeshenkova, G. G. and Ryazantseva, N. Z., 6th ICCCj Moscow (1974). Kawada, N., Sato, K. and Hashimoto, M., 6th Symp. Composite Mater. (1973); QthlCCC, Mosoow (1974). Terrier, P. and Moreau, M., Cem.-Wapno-Gips 2£, 115 (1975). Sauman, Z., Silikaty \9_, 193 (1975).

Electron and Optical Microscopy 405. 406. 407. 408. 409. 410. ill. 412. 413. 414. 415. 416. 417. 418. 419. 420. 421. 422. 423. 424. 425. 426. 427. 428. 429. 430. 431. 432. 433. 434. 435. 436. 437. 438. 439. 440. 441. 442. 443. 444. 445. 446. 447. 448. 449. 450. 451. 452.

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Collepardi, M., Marcialis, A., Massida, L. and Sanna, U., Cem. Conor. Res. J3, 497 (1976). Diamond, S. Ravina, D. and Lovell, J., Cem. Conor. Res. }0_, 297 (1980). Ogawa, K., Uchikawa, H., Takemoto, K. and Yasui, I., Cem. Conor. Res. j_0, 683 (1980). Beaudoin, J. J. and Feldman, R. F., J. Mater. Soi. _T4, 1681 (1979). Montgomery, D. G., Hughes, D. C. and Williams, R. I. T., Cem. Conor. Res. JJ_, 591 (1981). Grutzeck, M. W., Roy, D. M. and Scheetz, B. E., Cem. Conor. Res. _Π_, 291 (1981). Diamond, S., Cem. Conor. Res. Jj_, 383 (1981). Mehta, P. K., Cem. Conor. Res. JJ_» 5 0 7 (1981). Matkovic, B., and Young, J. F., Nature Rhys. Soi. J246, 79 (1973). Chatterji, S., Nature 250, 443 (1974). Young, J. F., Matkovic, B., Nature 250, 443 (1974). Beaudoin, J. J. and Ramachandran, V. S., Cem. Conor. Res. _5> 6 1 ? (1975). Stevula, L. and Petrovic, J., Silikaty J_9» 331 (1975). Lach, V. and Miskovsky, J., Silikaty _20, 23 (1976). Newesely, H., Monatsh. Chem. jj05, 840 (1974). Jambor, J., Epitoanyag 23_, 121 (1971). Mindess, S. and Gilley, J. C., Cem. Conor. Res. J3, 821 (1973). Suzuki, K., Urakawa, T. and Ito, S., Chem. Abstr. £2, 128761 (1975). Mitsuda, T. and Taylor, H. F. W. , Cem. Conor. Res. _5, 203 (1975). Knudsen, T. and Thaulow, N., Cem. Conor. Res. 5, 443 (1975). Sauman, Z., Cement (Zagreb) J_8, 9 (1975); SiliZaty 20, 136 (1976). Blank, N. B., Chem. Abstr. 85_, 165681 (1976). Kubo, K., Monoura, R. and Yamaguchi, G., Ceram. Abstr. _55, 2 (1976). Suzuki, K., Asakawa, K. Tuchida, Y., Ito, S. and Hukuo, K., Chem. Abstr. £7, 171974 (1977). Chan. C-F. and Mitsuda, T., Chem. Abstr. 87_, 156221 (1977). Lee, K. H., Daimon, M., Asaga, K., Nishikawa, T., Goto, S. and Kondo, R., Chem. Abstr. £6, 94977 (1977). Hasaba, S., Kawamura, M. and Okada, M., Chem. Abstr. 87_, 140230 (1977); 88, 40839 (1978). Kataeva, L. I. and Batalin, B. S., Chem. Abstr. 92» 136843 (1980). Kawamura, M. and Torii, K., 23rd ReV. Gen. Mtg. Teoh. Sess. - Cem. Assoo. Japan, 328 (1979). Ishii, T., Chan, C-F. and Mitsuda, T., Chem. Abstr. _93, 191038 (1980). Diamond, S., CE-MAT-1-78, 4th Proo. Int. Conf. Eff. Alkalies Cem. Conor. 181 (1980). Barnes, B. D., Diamond, S. and Dolch, W. L., Cem. Conor. Aggregates J_, 21 (1979). Bachiorrini, A. and Cussino, L., Cemento 77, 183 (1980). Kroenert and Haubert, P., Zem.-Kalk-Gips 25, 553 (1972). Haubert, P. and Kroenert, W., Tonind.-Ztg. \0\_, 28 (1977). Lehmann, H. and Rieke, K., Tonind.-Ztg. 97_, 157 (1973). Murât, M., Tonind.-Ztg. £8, 73 (1974). Murat, M., Karmazsin, E. and Charbonnier, M., Compt. Rend. 278C, 167 (1974). Murat, M., Tonind.-Ztg. 99_, 110 (1975). Scholze, H., Tonind.-Ztg. 9£, 185 (1975). Bertoldi, G. A., Zem.-Kalk-Gips _29, 469 (1976). Keckarovska, L. and Stamboliev, H., Chem. Abstr. 85, 112115 (1976). Murat, M. and Arnaud, Y., in RILEM Inter. Symp. Caiovum Sulfates and derived Materials3 Paris, 1977, ed. M. Murat and M. Foucault, p. 27. Murat, M., in RILEM Inter. Symp. 1977, p. 59. Hamori, G., in RILEM Inter. Symp. 1977, p. 253. Yamada, T., Suzuki, K. and Sato, K., Chem. Abstr. 8i5, 110440 (1977). Bertoldi, G. A., Zem.-Kalk-Gips 3\_, 12 (1978). Jarmontowicz, A., Cem.-Wapno-Gips 31, 236 (1978).

Part 2: Optical Microscopy CONTENTS 1 Introduction 2 Clinker 3 Phases in Clinker A Cement Paste and Cement Mineral Hydration 5 Corrosion of Concrete References 1

789 790 790 790 791 791

INTRODUCTION

Optical microscopy proved a useful tool for both qualitative and quantitative examination of clinker. Midgley [1] discussed, this method concentrating on the examination of polished and etched surfaces of Portland cement clinker. Plates are presented of C3 S, ß-C2S, MgO, CaO and interstitial material (C3A, C^AF). Various types of apparatus have been invented to try to measure the amounts of the various phases. A comparatively modern method was offered by Chayes [2]. The reproducibility of the method is quite good, but care should be taken, as the results are obtained as volume percentages of the constituents which' should be converted to weight percentages for comparison with other methods. Midgley and Taylor [3] reviewed the optical microscopy of both thin polished sections and crushed material by three main techniques: binocular, polarizing (for small fragments and thin transparent sections) and reflected light microscope. Differential etching is useful in identifying the various constituents in Portland cement clinker. In recent years other instrumental methods such as atomic absorption, X-ray fluorescence, infra-red and Raman spectroscopy and, of course, scanning electron microscopy and scanning transmittance electron microscopy, have greatly reduced the use of optical microscopy.

789

790

L. Ben-Dor 2

CLINKER

The structure of clay, limestones and marls [4-5] was studied in an attempt to correlate the microscopic data with the clinker produced from the raw materials. Cements produced by plasma fusion were studied [6]. A review of the use of polished section clinker microscopy in evaluating effects in raw mix, fineness and composition variations was published [7]. The advantage of microscopic techniques for such evaluations was discussed [8]. Optical photographs of lightweight cellular (aerated) mortars were included in a report of the properties of such materials [9]. 3

PHASES IN CLINKER

Automatic image analysis in conjunction with polished sections was used to analyze quantitatively phases of clinker [10]. The etchants used provided a strong constrast between phases but the results themselves were rather poor. Description of clinker minerals viewed in both reflected and transmitted light were given [11] with emphasis on the Ono method [12], XRD coupled with microscopy [13] was found to give a more complete phase analysis of a clinker than the Bogue composition calculated from XRF data. A microscopic method was used for quantitative evaluation of the four minerals: C3S, C2S, C3A and G+AF [14-15]. Reflected light microscopy was used for quantitative measurements of alite, bellte and interstitial phases [16] and differences were found from calculated compositions according to Bogue. The morphology of bellte [17-19] and that of minor interface components [20] was also studied by reflected light. Particle size has an effect on quantitative optical microscopy techniques [21 ] and the error was found to increase with belite content. Polymorphism of C3S was studied and a new monoclinic phase discovered in a microscopic study [22]. In a series of studies [23-26] the optical properties of C3A were discussed. Epoxy resin impregnation was used for filling pores and cracks due to drying during preparation of polished samples [27-28]. It was possible to differentiate between alite and belite after polish and etch. Cracks in stressed specimens [29] were studied by diffuse light optical microscopy. A resin impregnation and etching was developed to show fine cracks in glass fibre reinforced cement but the method is useful for studying plain cements and mortars [30]. 4

CEMENT PASTE AND CEMENT MINERAL HYDRATION

An automatic image analyzer was used for measuring the paste content in mortars and concretes [31]. Various microscopical methods were used to show spherical pores, voids and pore channel systems in hardened cement paste [32], Long term effect of chlorides on cement and concrete was studied and the accelerated corrosion and development of sulphoaluminate needles were shown [33], The hydration of expansive cement was studied and the hydration products: CH, gypsum and sulphoaluminates were observable after 30h [34]. A hydration scheme for C3 S, as observed by optical microscopy, had been proposed considering the reaction to be topochemical [35]. Optical microscopy showed that the growth pattern of CH formed during C3S hydration was strongly influenced by the presence of admixtures [36]. Also, the path of fracture in hardened C3S paste changed with age [37]. Another study [38] correlated the

Electron and Optical Microscopy

791

growth of CH crystals to the physical properties of C3S mortars and optical microscopy was the main tool used. The formation and the hydration properties of calcium silicates was found to be modified by BaSO^ [39]. The morphology of CSH and CH and the size of the latter was studied by optical microscopy during the hydration of C3S, C2S and their mixture [40]. 5

CORROSION OF CONCRETE

Certain dolomitic aggregates were shown to have a deleterious reaction with cement pastes [41]. The effect was viewed on thin sections. Using a similar technique [42] a possible connection was found between sulphate attack and alkali-aggregate reaction. Microscopy gave evidence of epitaxical growth of certain hydration products on the surface of aggregates [43]. A correlation was found between the quality of the aggregate material and its bond to the paste, and the complexity of the microcrack formed during fracture [44], Sulphate corrosion of alite mortars was monitored [45] and also the damage of concrete after wetting-drying cycles [46]. General and pitting attack was observed microscopically on a concrete structure near a lake [47]. The factors responsible for the deterioration were: the quality of the concrete, the salt water used for mixing, the Cl" and SO* diffusing from the underground water and the vibrations. REFERENCES 1. H. G. Midgley in The Chemistry of Cements, ed. H. F. W. Taylor, Academic Press London (1964), Vol 1, chap 3, p. 106, 121. 2. F. Chayes, Pétrographie Model Analysis, New York (1956). 3. H. G. Midgley and H. F. W. Taylor in The Chemistry of Cements, ed. H. F. W. Taylor, Academic Press London (1964), Vol 2, chap 20, p. 223. 4. B. Tavasci, Cemento 73_9 139 (1976). 5. Y. Kihara and J. V. Valarelli, Chem. Abstr. 86, 21004 (1977). 6. F. P. Glasser, Cem. Conor. Res. 5_f 55 (1975). 7. H. D. Dorn, Cem. Conor. Res. 8_, 635 (1978). 8. W. Cieslinski, Cem.-Wapno-Gips 32, 285 (1978). 9. M. Venuat and M. Tran-Thanb-Phat, Cim., Betons, Plâtres,°Chaux (693) 99 (1975). 10. F. Hofmanner, Zem.-Kalk-Gips 28, 363 (1975). 11. F. A. DeLisle, Cem. Teohnol. ]_, 93 (1976). 12. Y. Ono, Cem. Res. Prog. 1976, chap 2, p. 15. 13. M. Kristmann, Cem. Conor. Res. 2» 649 (1977). 14. T. Knudsen, Amer. Ceram. Soo% Bull. ,55, 1052 (1976). Betons, 15. Comité d'Etudes Techniques de L'Industrie du Cement, Cim., Plates, Chaux (713) 205 (1978). 16. S. Helle, Ceram. Abstr. 56,, 159 (1977). 17. S. L. Sarkar, Miorosoope 27, 391 (1977). 18. B. Tavasci, Cemento _75, 363 (1978). 19. A. I. Boikova, L. V. Grishchenko, G. P. Nilova and A. I. Domanskii, Tsement (7), 9 (1980). Paris 20. F. X. Deloye and N. Louarn, Bull. Liaison Labs. Ponts Chaussées, 71 (1975). 21. S. Chromy, Silikaty 22, 215 (1978). 22. I. Maki and S. Chromy, Cem. Conor. Res. £, 407 (1978). 23. I. Maki, Cem. Conor. Res. 2> 295 (1973). 24. I. Maki, Cem. Conor. Res. 4_, 87 (1974) 25. I. Maki, Cem. Conor. Res. 16, 183 (1976). 26. I. Maki, Cem. Conor. Res. 6, 797 (1976).

792 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47.

L. Ben-Dor S. L. Sarkar, World Cem. Teohnol. JO, 312 (1979). D. H. Bager and E. J. Sellevold, Cem. Conor. Res. _9, 653 (1979). D. D. Higgins and J. E. Bailey, Hydraulic Cement Pastes^ Proc. Conf. University of Sheffield, 1976 (Cem. Concr. Assoc, Wexham Springs, England, 1976, p. 283). A. C. Jaras, Cem. Conor. Res. 6i, 377 (1976). H. Gudmundsson, S. Chatterji, A. Damgaard Jensen, N. Thaulow and P. Christensen, Cem. Conor. Res. 9.» 6 0 7 (1979). N. McN. Alford and A. A. Rahman, J. Mater. Soi. J_6, 3105 (1981). M. Ben-Yair, Cem. Conor. Res. 4_, 405 (1974). M. Ish-Shalom and A. Bentur, Cem. Conor. Res. _4, 519 (1974). P. Terrier and M. Moreau, Cim. Betons (Rev. Mater. Constr.) (613), 379 (1966). R. L. Berger and J. D. McGregor, Cem. Concr. Res. 2^, 43 (1972). R. L. Berger, F. V. Lawrence Jr. and J. F. Young, Cem. Concr. Res. 3_> 497 (1973). J. P. Boyer, M.Sc. Thesis, University of Illinois, Urbana 1976. B. Matkovic, V. Carin, T. Gacesa, R. Halle, I. Jelenic and J. F. Young, Ceram. Soc. Bull. 6£, 825 (1981). J. H. Kung, Ph.D. Thesis, University of Illinois, Urbana 1978. W. J. French and A. B. Poole, Cem. Conor. Res. 4·, 925 (1974). K. Pettifer and P. J. Nixon, Cem. Conor. Res. J[0, 173 (1980). L. Struble, J. P. Skalny and S. Mindess, Cem. Conor. Res. J£, 277 (1980). P. E. Petersson, Cem. Conor. Res. JjO, 91 (1980). P. K. Mehta, D. Pirtz and M. Polivka, Cem. Concr. Res. £, 439 (1979). N. V. Waubke and R. Weiss, Cem. Conor. Res. 9_, 553 (1979). H. A. El-Sayed, S. M. El-Sayed and V. K. Gouda, Cem. Conor. Res. JJ_, 351 (1981).