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Concrete technology and design, vol. 1. New concrete materials
Book reviews
are renowned for their contribution to cement literature. The international nature of the authorship has ensured that the book presents a global picture of current knowledge and world-wide developments. Each chapter, supported by an extensive bibliography, is developed in such a way that the book should appeal not only to those with limited understanding of the material, but also to experts, although not every chapter will appeal to all readers. Quite rightly the first chapter is devoted to silicate structures and the various techniques used for their analysis such as electron microscopy, EXAFS and NMR spectroscopy. The cement clinkering reactions discussed in the second chapter concentrate on the kinetics of processes in the anhydrous stages of cement manufacture. The crystal chemistry of portland cements is described in chapter three. The polymorphism and solid solutions of the four principal minerals are analysed and then related to industrial clinker minerals. Chapter four deals with the microscopy of unhydrated portland cement. Optical and electron microscopy together with their additional capabilities to extract structural and chemical information are reported in this chapter in great detail. Portland cement production is the theme of chapter five. With the need to conserve energy and materials and to produce at the same time cement of consistent quality, several aspects of cement manufacture such as raw materials, raw materials preparation, heat treatment and cement milling are discussed. The hydration mechanisms of cements have always created controversy, and to present a balanced overview of current theories and to evaluate recent advances is no easy task. Chapter six has, nevertheless, successfully done this by discussing the hydration processes of the individual components and interacting these with the hydration and microstructure of cement. One omission in this excellent chapter is the hydration of blended cements, particularly since such cements are increasingly in practical use. The mechanical performance of cementitious systems is discussed in chapter seven - - the structure, deformation and fracture of both the hardened cement paste and of concrete are dealt with, although the most important of all, the aggregate-matrix interface, is only briefly touched upon. Chapter eight on durability describes the various kinds of cement degradation and their influence on structural members. Alkali-aggregate reactivity gets special treatment, whilst others such as steel corrosion and degradation of glass fibres are only briefly treated. It is a bit surprising that blended cements have not again been mentioned in this context. The last two chapters are devoted to industrial aluminous cements and special cements. Several aspects of aluminous cements are dealt with in chapter nine with emphasis on the phenomenon of conversion and the prescriptions for durability. The cements discussed in the last chapter include fast setting and hardening cements, expansive cements, low-energy cements, magnesium cements and dental cements. This is clearly an outstanding and thorough compilation of the current knowledge on portland and other cements which would be welcomed by everyone concerned.
130
Concrete Technology and Design, Vol. 1. N e w Concrete Materials
Edited by R. N. Swamy Published by Surrey University Press, Blackie and Son Ltd, Bishopbriggs, Glasgow G64 2NZ, Scotland, 1983 ISBN 0 903384 34 5, Price £17.95, x + 180 pp. This is the first volume in what promises to be a very interesting new series, whose intention is to draw attention to the inherent properties of concrete materials and their significance with respect to design and construction. Seven eminent international contributors give a state-ofthe-art report on sulphur concrete, expanded polystyrene concrete, ultra-rapid hardening cement and the use of waste materials and by-products in concrete construction respectively. The first report is subdivided into two sections; sulphur concrete and sulphur-infiltrated concrete. Sulphur concrete consists entirely of elemental sulphur and aggregates and contains neither cement nor water. Details are given of the particular process technology involved which necessitates blending the ingredients in a conventional mixer equipped with a heater to form a flowable homogeneous mixture. The resulting concrete has many virtues such as high early strength, improved fatigue performance and since it contains no water its performance in freeze-thaw conditions is more a problem of its resistance to thermal cycling. Unfortunately sulphur has a low melting point and is vulnerable to combustion with the production of toxic gases. It also has a tendency to corrode reinforcement under humid and wet conditions which renders it unsuitable for most structural uses. As the author confirms it is rather a specialised material which really only comes into its own in Arctic-like regions where normal portland cement concretes cannot be used. Sulphur-infiltrated concrete has been developed as a more economical way of providing high strength and durability than by polymer-impregnation particularly in regions (such as N. America and Canada) where there is a surplus of sulphur with regard to normal industrial usage. The process consists basically of immersing the precast units in molten sulphur with the possible additional procedures of applying a vacuum and external pressure. This impregnation of voids and fissures gives large increases in strength. The high ~mpermeability achieved produces greatly enhanced durability particularly against freeze-thaw cycling and acid attack. The main applications for sulphur-infiltrated concrete (SIC) are obviously in the precast industry with such units as paving slabs, kerbs and tunnel linings and could be a valuable alternative where conventional concrete has a limited life expectancy. The second report deals with the production and properties of expanded polystyrene concrete. This author begins by tracing the development, manufacture and physical properties of the raw and expanded polystyrene beads. The particular problems associated with the handling, mixing, compacting and curing of concrete containing these ultra-lightweight particles are fully discussed. Mix design is seen to be not so much based on obtaining a specific crushing strength as on achieving an optimum balance between density, thermal insulation, adequate strength and cost. Typical mixes are detailed together with recorded values for wetting expansion, drying shrinkage, creep and deformation after fatigue loading. The higher than normal water absorption property necessb
Book reviews
tates larger cover to prevent corrosion of reinforcement and has resulted in the development of sandwich cladding panels with reinforced (normal or fibre) normal-weight concrete facings and an expanded polystyrene concrete core. A full discourse is given on the use of various forms of precast panels and fixings for low-cost housing and cladding panels in various parts of the world. The third and largest section in this book is devoted to ultra-rapid hardening cement (jet cement). This is an entirely new type of cement which was originally developed and patented in the United States and has been on the market there, Japan and Germany since the early 70s. In the manufacture of jet cement clinker, bauxite, kaolinite and fluorite are incorporated in addition to the ordinary raw materials used for portland cement. The ground clinker is then homogeneously mixed with manufactured anhydrite. The resulting cement has the property of ultra-rapid hardening and super high early strength. The setting time can also be arbitrarily controlled and the cement shows a stable strength development over a long period of time. The sub-sections dealing with the chemistry and hydration of jet cement clinker are very specialised and mainly of interest to research workers in this particular field. However the in-depth study does tend to convince the reader that jet cement is not just a 'flash in the pan' but is a reliable and well controlled process. The physical properties of jet cement are detailed in comparison with ordinary portland cement illustrating in particular its high early strength and very short setting time. For most practical applications a retarder such as citric acid is used to regulate the rate of hydration. Another important attribute is its good strength development at low temperature which makes it particularly suitable for winter concreting. Air-entrainment and the use of fly ash have both been shown to be effective with jet cement. Several examples of the practical application of jet cement are also detailed and illustrated covering urgent and repair work, winter concreting, precast products and grouting. The cost is relatively high but it is undoubtedly a very versatile and interesting construction material. The final section deals with the use of waste materials and industrial by-products in concrete construction, the main subdivisions used being organic, inorganic and industrial waste materials which could be used as economic substitutes for conventional materials. The first category encompasses such materials as sawdust, cork granules, coconut pith and rice husks. The main application is for lightweight concrete and building units in developing countries. The concern here is for the long term stability and durability of these products. Of more local interest is the possible utilisation of inorganic (urban) wastes such as those obtained from selective demolition work, 'clean' concrete, broken brick and glass. Research has indicated that concrete of adequate quality can be made using crushed concrete rubble for both coarse and fine aggregates. The recycling of pavement concrete for base and subbase material used in the form of lean-concrete is particularly interesting in view of the need to renew rather than repair many of our now ageing motorways. The use of industrial
wastes in this country is now fairly well advanced particularly with reference to blast-furnaced slag for use in the manufacture of blast-furnace cement, air-cooled slag for dense aggregate or foamed to give lightweight aggregate particles. Another familiar waste material referred to is coal ash from selected power stations. The use of pulverised fuel ash as a cement replacement (or more correctly in conjunction with ordinary portland cement) is now well established and reference is made to some selected research works. Brief mention is also made of the possible use of the several other less familiar miscellaneous wastes and by-products, the main virtue being the removal and possible economic use of what would otherwise be environmental pollutants. In conclusion this is an interesting and informative publication which covers a comprehensive range of new concrete materials in considerable depth. It has the virtue of not only drawing attention to these innovations but also, by virtue of the extensive bibliographies, providing the means whereby additional information can be readily obtained. Well worth adding to your personal collection for present and future use.
Post-tensioned Flat-slab Design Handbook, Concrete Society Tehnical Report No. 25, Ref. No. 53.044. Published by The Concrete Society, and available from Publications Distribution, Cement and Concrete Association, Wexham Springs, Slough SL3 6PL, 1984
ISBN 0 7210 1297 3, Price £5.50, £2.75 to members, 44 pp. The structural advantages of post-tensioning concrete flat slab floors have been recognised throughout the world and have resulted in many economic designs and construction. The present publication, prepared by a working party of the Prestressing Equipment Manufacturers Association, is a design guide to the Concrete Society Technical Report No. 17 which deals with post-tensioned flat slab construction with special emphasis on unbonded tendons. The handbook initially presents a detailed account of the flexural and shear behaviour of one-way slabs and flat plates. This is followed by guidance on the selection of structural form in relation to column layout, slab thickness and type of slab construction. The design process is then discussed in great detail and reference is made to analysis, flexural strength, shear and deflection. There is a very useful section of detailing and guidance is given on a number of aspects such as reinforcement layout, concreting, joints, and anchorage protection. Appendix A contains two worked out design examples - one of an office building with unbonded tendons and the other, a flat slab with drop panels and bonded tendons. There are two additional Appendices which give information on the stiffness and carry-over factors for frame analysis and on the calculation of tendon geometry. A selected bibliography is also provided. The handbook is well illustrated. This is a very practical design guide which should be of great help to designers and contractors alike.
131
are renowned for their contribution to cement literature. The international nature of the authorship has ensured that the book presents a global picture of current knowledge and world-wide developments. Each chapter, supported by an extensive bibliography, is developed in such a way that the book should appeal not only to those with limited understanding of the material, but also to experts, although not every chapter will appeal to all readers. Quite rightly the first chapter is devoted to silicate structures and the various techniques used for their analysis such as electron microscopy, EXAFS and NMR spectroscopy. The cement clinkering reactions discussed in the second chapter concentrate on the kinetics of processes in the anhydrous stages of cement manufacture. The crystal chemistry of portland cements is described in chapter three. The polymorphism and solid solutions of the four principal minerals are analysed and then related to industrial clinker minerals. Chapter four deals with the microscopy of unhydrated portland cement. Optical and electron microscopy together with their additional capabilities to extract structural and chemical information are reported in this chapter in great detail. Portland cement production is the theme of chapter five. With the need to conserve energy and materials and to produce at the same time cement of consistent quality, several aspects of cement manufacture such as raw materials, raw materials preparation, heat treatment and cement milling are discussed. The hydration mechanisms of cements have always created controversy, and to present a balanced overview of current theories and to evaluate recent advances is no easy task. Chapter six has, nevertheless, successfully done this by discussing the hydration processes of the individual components and interacting these with the hydration and microstructure of cement. One omission in this excellent chapter is the hydration of blended cements, particularly since such cements are increasingly in practical use. The mechanical performance of cementitious systems is discussed in chapter seven - - the structure, deformation and fracture of both the hardened cement paste and of concrete are dealt with, although the most important of all, the aggregate-matrix interface, is only briefly touched upon. Chapter eight on durability describes the various kinds of cement degradation and their influence on structural members. Alkali-aggregate reactivity gets special treatment, whilst others such as steel corrosion and degradation of glass fibres are only briefly treated. It is a bit surprising that blended cements have not again been mentioned in this context. The last two chapters are devoted to industrial aluminous cements and special cements. Several aspects of aluminous cements are dealt with in chapter nine with emphasis on the phenomenon of conversion and the prescriptions for durability. The cements discussed in the last chapter include fast setting and hardening cements, expansive cements, low-energy cements, magnesium cements and dental cements. This is clearly an outstanding and thorough compilation of the current knowledge on portland and other cements which would be welcomed by everyone concerned.
130
Concrete Technology and Design, Vol. 1. N e w Concrete Materials
Edited by R. N. Swamy Published by Surrey University Press, Blackie and Son Ltd, Bishopbriggs, Glasgow G64 2NZ, Scotland, 1983 ISBN 0 903384 34 5, Price £17.95, x + 180 pp. This is the first volume in what promises to be a very interesting new series, whose intention is to draw attention to the inherent properties of concrete materials and their significance with respect to design and construction. Seven eminent international contributors give a state-ofthe-art report on sulphur concrete, expanded polystyrene concrete, ultra-rapid hardening cement and the use of waste materials and by-products in concrete construction respectively. The first report is subdivided into two sections; sulphur concrete and sulphur-infiltrated concrete. Sulphur concrete consists entirely of elemental sulphur and aggregates and contains neither cement nor water. Details are given of the particular process technology involved which necessitates blending the ingredients in a conventional mixer equipped with a heater to form a flowable homogeneous mixture. The resulting concrete has many virtues such as high early strength, improved fatigue performance and since it contains no water its performance in freeze-thaw conditions is more a problem of its resistance to thermal cycling. Unfortunately sulphur has a low melting point and is vulnerable to combustion with the production of toxic gases. It also has a tendency to corrode reinforcement under humid and wet conditions which renders it unsuitable for most structural uses. As the author confirms it is rather a specialised material which really only comes into its own in Arctic-like regions where normal portland cement concretes cannot be used. Sulphur-infiltrated concrete has been developed as a more economical way of providing high strength and durability than by polymer-impregnation particularly in regions (such as N. America and Canada) where there is a surplus of sulphur with regard to normal industrial usage. The process consists basically of immersing the precast units in molten sulphur with the possible additional procedures of applying a vacuum and external pressure. This impregnation of voids and fissures gives large increases in strength. The high ~mpermeability achieved produces greatly enhanced durability particularly against freeze-thaw cycling and acid attack. The main applications for sulphur-infiltrated concrete (SIC) are obviously in the precast industry with such units as paving slabs, kerbs and tunnel linings and could be a valuable alternative where conventional concrete has a limited life expectancy. The second report deals with the production and properties of expanded polystyrene concrete. This author begins by tracing the development, manufacture and physical properties of the raw and expanded polystyrene beads. The particular problems associated with the handling, mixing, compacting and curing of concrete containing these ultra-lightweight particles are fully discussed. Mix design is seen to be not so much based on obtaining a specific crushing strength as on achieving an optimum balance between density, thermal insulation, adequate strength and cost. Typical mixes are detailed together with recorded values for wetting expansion, drying shrinkage, creep and deformation after fatigue loading. The higher than normal water absorption property necessb
Book reviews
tates larger cover to prevent corrosion of reinforcement and has resulted in the development of sandwich cladding panels with reinforced (normal or fibre) normal-weight concrete facings and an expanded polystyrene concrete core. A full discourse is given on the use of various forms of precast panels and fixings for low-cost housing and cladding panels in various parts of the world. The third and largest section in this book is devoted to ultra-rapid hardening cement (jet cement). This is an entirely new type of cement which was originally developed and patented in the United States and has been on the market there, Japan and Germany since the early 70s. In the manufacture of jet cement clinker, bauxite, kaolinite and fluorite are incorporated in addition to the ordinary raw materials used for portland cement. The ground clinker is then homogeneously mixed with manufactured anhydrite. The resulting cement has the property of ultra-rapid hardening and super high early strength. The setting time can also be arbitrarily controlled and the cement shows a stable strength development over a long period of time. The sub-sections dealing with the chemistry and hydration of jet cement clinker are very specialised and mainly of interest to research workers in this particular field. However the in-depth study does tend to convince the reader that jet cement is not just a 'flash in the pan' but is a reliable and well controlled process. The physical properties of jet cement are detailed in comparison with ordinary portland cement illustrating in particular its high early strength and very short setting time. For most practical applications a retarder such as citric acid is used to regulate the rate of hydration. Another important attribute is its good strength development at low temperature which makes it particularly suitable for winter concreting. Air-entrainment and the use of fly ash have both been shown to be effective with jet cement. Several examples of the practical application of jet cement are also detailed and illustrated covering urgent and repair work, winter concreting, precast products and grouting. The cost is relatively high but it is undoubtedly a very versatile and interesting construction material. The final section deals with the use of waste materials and industrial by-products in concrete construction, the main subdivisions used being organic, inorganic and industrial waste materials which could be used as economic substitutes for conventional materials. The first category encompasses such materials as sawdust, cork granules, coconut pith and rice husks. The main application is for lightweight concrete and building units in developing countries. The concern here is for the long term stability and durability of these products. Of more local interest is the possible utilisation of inorganic (urban) wastes such as those obtained from selective demolition work, 'clean' concrete, broken brick and glass. Research has indicated that concrete of adequate quality can be made using crushed concrete rubble for both coarse and fine aggregates. The recycling of pavement concrete for base and subbase material used in the form of lean-concrete is particularly interesting in view of the need to renew rather than repair many of our now ageing motorways. The use of industrial
wastes in this country is now fairly well advanced particularly with reference to blast-furnaced slag for use in the manufacture of blast-furnace cement, air-cooled slag for dense aggregate or foamed to give lightweight aggregate particles. Another familiar waste material referred to is coal ash from selected power stations. The use of pulverised fuel ash as a cement replacement (or more correctly in conjunction with ordinary portland cement) is now well established and reference is made to some selected research works. Brief mention is also made of the possible use of the several other less familiar miscellaneous wastes and by-products, the main virtue being the removal and possible economic use of what would otherwise be environmental pollutants. In conclusion this is an interesting and informative publication which covers a comprehensive range of new concrete materials in considerable depth. It has the virtue of not only drawing attention to these innovations but also, by virtue of the extensive bibliographies, providing the means whereby additional information can be readily obtained. Well worth adding to your personal collection for present and future use.
Post-tensioned Flat-slab Design Handbook, Concrete Society Tehnical Report No. 25, Ref. No. 53.044. Published by The Concrete Society, and available from Publications Distribution, Cement and Concrete Association, Wexham Springs, Slough SL3 6PL, 1984
ISBN 0 7210 1297 3, Price £5.50, £2.75 to members, 44 pp. The structural advantages of post-tensioning concrete flat slab floors have been recognised throughout the world and have resulted in many economic designs and construction. The present publication, prepared by a working party of the Prestressing Equipment Manufacturers Association, is a design guide to the Concrete Society Technical Report No. 17 which deals with post-tensioned flat slab construction with special emphasis on unbonded tendons. The handbook initially presents a detailed account of the flexural and shear behaviour of one-way slabs and flat plates. This is followed by guidance on the selection of structural form in relation to column layout, slab thickness and type of slab construction. The design process is then discussed in great detail and reference is made to analysis, flexural strength, shear and deflection. There is a very useful section of detailing and guidance is given on a number of aspects such as reinforcement layout, concreting, joints, and anchorage protection. Appendix A contains two worked out design examples - one of an office building with unbonded tendons and the other, a flat slab with drop panels and bonded tendons. There are two additional Appendices which give information on the stiffness and carry-over factors for frame analysis and on the calculation of tendon geometry. A selected bibliography is also provided. The handbook is well illustrated. This is a very practical design guide which should be of great help to designers and contractors alike.
131