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Influence of glass powder on the durability properties of engineered cementitious composites
Construction and Building Materials 242 (2020) 118199
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Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Influence of glass powder on the durability properties of engineered cementitious composites Adeyemi Adesina, Sreekanta Das ⇑ Department of Civil and Environmental Engineering, University of Windsor, Windsor, Ontario, Canada
h i g h l i g h t s Glass powder was used to partially replace the binder component in ECC up to 50%. Alkali-silica reaction, shrinkage and permeability of the ECC was evaluated. Microstructural properties of mixtures was investigated. No trace of alkali-silica reaction in the ECC mixtures.
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Article history: Received 14 August 2019 Received in revised form 6 January 2020 Accepted 14 January 2020
Keywords: Engineered cementitious composite (ECC) Glass powder Durability Green material Microstructure
a b s t r a c t This paper presents outcomes of investigation on various durability properties of engineered cementitious composites (ECC) incorporating glass powder as the cementitious material. The Durability was evaluated by assessing the shrinkage, permeability, and alkali-silica reaction resistance of the ECC mixtures. Shrinkage properties investigated are plastic, autogenous and drying shrinkage. The permeability properties evaluated are porosity, water absorption, sorption, sorptivity and chloride ion penetration. Results from this study showed that glass powder can be used to significantly reduce the shrinkage of ECC mixtures, however, there is a negative effect on its permeability properties. On the positive side, no occurrence of the alkali-silica reaction was observed in any ECC mixtures incorporating glass powder. Based on the overall performance of ECC mixtures incorporating glass powder, the replacement of 25% fly ash with glass powder was found to be the optimum. Ó 2020 Elsevier Ltd. All rights reserved.
1. Introduction The last decade has seen a rapid enhancement and development of various cementitious composites. One of the promising cementitious composites developed in the last decade is called engineered cementitious composite (ECC), and the termed ‘‘engineered” in ECC is coined based on the micromechanics design in which the composite is based [1]. ECC has superior performance when compared to conventional concrete. The strain capacity of ECC is several hundred times larger than that of regular cement concrete, and its crack width usually less than 60 mm equipped the composite with enhanced mechanical and durability properties [2]. In order to achieve the higher tensile capacity and lower permeability, higher content of fly ash (FA) in the range of 1.2–4.2 times Portland cement (PC) is used in conventional ECC mixtures [3–6]. ⇑ Corresponding author. E-mail addresses: [email protected] (A. Adesina), [email protected] (S. Das). https://doi.org/10.1016/j.conbuildmat.2020.118199 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved.
As the world is becoming more sustainability conscious, the supply of FA is expected to reduce significantly in the coming years especially in developed countries like the USA and Canada due to the rapid decommissioning of coal-powered plants. Therefore, it is paramount to find alternative materials that can be used to partially or totally replace FA in ECC mixtures. One of the wastes generated in large quantities and less incorporated into ECC mixtures is glass wastes. Glass wastes have been used extensively used in ordinary Portland cement (OPC) concrete mixtures as aggregate and/or replacement of OPC depending on its size [7–11]. However, its application in ECC mixture is very limited. Therefore, in order to further improve the sustainability of ECC while conserving the supply of FA, recycled glass in form of powder (i.e. glass powder) can be used in ECC mixtures. Glass powder (GP) can be incorporated into cementitious materials as partial replacement of the binders due to its pozzolanic properties [11–14]. However, it is worth to mention that its pozzolanic reaction is slower when compared to that of FA [11,12,14,15]. Siad et al. [16] were able to use glass powder up to 60% to replace FA in ECC mixtures, however, only the chloride permeability and the electrical resistivity were the
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durability properties assessed. In order to fully utilize GP in ECC mixtures, it is paramount to evaluate other durability properties of the cementitious composite especially its shrinkage, permeability and resistance to deleterious reactions such as alkali-silica reaction. Though the study by Siad et al. [17] showed that GP can replace FA totally in ECC, a preliminary study by the authors to evaluate the effect of GP on the mechanical properties of ECC mixtures showed that only the use of GP up to 1.1 times the OPC or 50% replacement of FA is practical to produce a structural grade ECC. Also, it is worth to mention that the ECC mixtures evaluated in this study are intended to be used as a construction or repair material for pavements. Therefore, this study was designed and undertaken to investigate the effect of glass powder (GP) used up to 50% replacement of FA in ECC mixtures on its durability properties. Durability properties evaluated include plastic shrinkage, autogenous shrinkage, drying shrinkage, porosity, water absorption, sorption, sorptivity, chloride ion penetration and alkali-silica reaction. The microstructural investigation was also carried by obtaining scanning electron microscopy (SEM) images and carrying out energy-dispersive Xray spectroscopy (EDS) analysis. 2. Experimental program
Details about the ECC mixtures evaluated in this study are presented in Table 3. The ratio between the FA and GP was kept unchanged at 2.2 by mass of the PC for all mixtures, and the water to binder ratio was maintained at 0.25. The mixture ID indicated in Table 3 represents the proportion of GP used as a percentage of the FA content. For example, the 25 GP and 50 GP indicate 25% and 50% replacement of the FA with GP respectively.
2.2. Mixing and curing All mixtures were prepared using a 70 L Hobart mixer. The binder (i.e. OPC, FA and GP) and aggregates were first dry mixed for 2 min, followed by the addition of water premixed with SP were then added to the mixture and mixed for another 2 min. Oil coated PVA fibres are then slowly added to the mixture and mixed for an additional 2 min. Immediately after mixing, the fresh mixtures were placed in different moulds associated with the tests to be carried out and covered with a plastic sheet to avoid loss of moisture or as required by the test method. After approximately 24 h after casting, the specimens were demoulded and cured under water till the testing age or as required by the test procedure.
2.3. Test methods 2.3.1. Compressive strength Compressive strength was carried out in accordance with ASTM C 109 [18] on cube specimens with a dimension of 50 mm 50 mm 50 mm. For each mixture, four specimens were evaluated, and the average compressive strength was determined.
2.1. Materials and mixture proportion Type 1 Portland cement (PC) alongside ASTM class F fly ash (FA) and glass powder (GP) was used as the binder in this study. The properties of the binders are presented in Table 1 and the SEM image of FA and GP are shown in Fig. 1. Micro-silica sand (SS) was used as aggregate and polyvinyl alcohol (PVA) fibres with properties presented in Table 2 were used to reinforce the ECC mixtures. To improve the interfacial properties between the fibre and the cementitious matrix, the PVA fibre used in this study had a coating with an oiling agent (at 1.2% by weight). In order to achieve excellent workability, an equal dosage of superplasticizer (SP) was used for all mixtures. Table 1 Chemical composition of binders and aggregate (%). Compound
PC
FA
GP
SS
CaO SiO2 Al2O3 Fe2O3 SO3 Na2O LOI
62.43 19.78 5.38 2.67 3.47 0.12 1.52
1.33 61.3 19.91 6.9 0.28 1.02 3.65
8.07 67.37 4.79 – – 14.81 0.4
19.17 46.65 6.6 3.07 – 1.13 –
2.3.2. Free plastic shrinkage The free plastic shrinkage of the ECC mixtures was evaluated using the test procedure similar to that of Booya et al. [19]. The test procedure entails using the environmental chamber with schematics shown in Fig. 2, and the mould setup presented in Fig. 3. The change in length of the mixtures captured by a linear variable differential traducer (LVDT) within the first four hours was used to assess the plastic shrinkage of the mixtures. The need the put the mould in the environmental chamber is necessary to accelerate the rate of water evaporation from the ECC mixtures.
2.3.3. Autogenous and drying shrinkage Immediately after mixing, four bar specimens with dimensions of 25 mm 25 mm 250 mm were cast with two copper studs embedded at the ends for the length change measurements. At approximately 24 h, the specimens were demoulded and cured in water for 24 h. Then the specimens were stored in the laboratory with ambient temperature and relative humidity (i.e. 25 ± 2 °C and 50 ± 5% RH respectively) for drying shrinkage. For autogenous shrinkage, the specimens were wrapped with aluminum foil and tape immediately after demoulding. Then these specimens were stored in the laboratory. Changes in length of each bar specimen in all mixtures for both autogenous and drying shrinkages were measured up to 28 days. The shrinkage of the mixtures was determined based on the change in length of the specimens compared to the initial length taken before the specimens were exposed to drying conditions.
Fig. 1. SEM image of (a) FA (b) GP.
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A. Adesina, S. Das / Construction and Building Materials 242 (2020) 118199 Table 2 Properties of PVA fibre. Length (mm)
Diameter (mm)
Tensile strength (MPa)
Young Modulus (GPa)
Elongation (%)
8
40
1600
41
6
Table 3 Mixture proportion (in ratio to PC). Mixture ID
PC
FA
GP
Sand/Binder
Water/Binder
SP
Fiber (% Vol.)
0 GP 25 GP 50 GP
1 1 1
2.2 1.6 1.1
0 0.6 1.1
0.38 0.38 0.38
0.25 0.25 0.25
0.015 0.015 0.015
2 2 2
Fig. 2. Schematics of plastic shrinkage setup.
Fig. 3. Mould setup for plastic shrinkage. 2.3.4. Porosity and water absorption The porosity (i.e. % voids) and absorption of each mixture were evaluated according to ASTM C 642 [20] test procedures. This test was carried out on cylindrical specimens with a diameter of 100 mm and a height of 50 mm. The porosity of the ECC mixtures was obtained from the resulting bulk density and apparent density, while the absorption was calculated based on the mass of the specimen after oven drying and immersion in water. 2.3.5. Sorption The bulk water sorption of the ECC mixtures was evaluated in accordance with ASTM C 1757 [21]. This test method uses the amount of water absorbed into cementitious composite within 30 min to evaluate the overall durability of the composite. Cylindrical specimens with 100 mm diameter and 50 mm height were first dried in the oven at 50 °C for approximately 48 h, followed by cooling down at room temperature for approximately 24 h. After the specimens have cooled down, they were fully immersed in water for 30 min and the sorption calculated based on the amount of water absorbed calculated from the mass change of the specimens. 2.3.6. Sorptivity The rate of water absorption (i.e. sorptivity) of the ECC mixtures was evaluated in accordance with the procedure in ASTM C 1585 [22]. In contrast to the sorption test (i.e. ASTM C 1757), the capillary water is retained in the pores. This test was
used to evaluate the rate at which water penetrates into an unsaturated specimen. Cylindrical specimens with a height of 100 mm and a diameter of 50 mm were conditioned and evaluated using the guidelines and procedures in ASTM C 1585. A schematic of the test setup for the absorption and sorptivity of the ECC mixtures is presented in Fig. 4.
2.3.7. Chloride ion penetration test This test was carried out in accordance with ASTM C 1202 [23] on cylindrical specimens with a diameter of 100 mm and 50 mm height. The cylindrical specimens were placed between 0.3 M NaOH and 3% solution and 60-V applied across as depicted in Fig. 5. The current passing through the setup was recorded using a data acquisition system, and the total charge for each mixture obtained from the average of two specimens evaluated for each mixture.
2.3.8. Alkali-silica reaction The incorporation of GP into ECC mixtures has called for a need to evaluate the resistance of the mixtures to alkali-silica reaction (ASR). The evaluation was carried out in accordance with ASTM C 1260 [24]. The test method entails soaking bar specimens with a dimension of 25 mm 25 mm 250 mm in 1 M NaOH and subjecting it to a temperature of 80 °C. The resistance of the mixtures was assessed based on the expansion measured in terms of length change of the specimens.
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Fig. 4. Test setup for sorptivity.
Fig. 6. Compressive strength of ECC mixtures at different ages. Fig. 5. Test setup for chloride ion penetration test. 2.3.9. Microstructural analysis The microstructural investigation was carried out on the ECC mixtures by using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). SEM was used to obtain microstructure images, and EDS was used to carry out the elemental analysis.
3. Results and discussion 3.1. Compressive strength The compressive strength of the ECC mixtures at different ages is presented in Fig. 6. It can be observed from Fig. 6 that the compressive strength of all the ECC mixtures increased with age, however, it reduced with increasing GP content. For example, the compressive strength of 25 GP at 7 days is 22.8 MPa, while at 14 and 28 days it was 30.4 and 35.8 MPa, respectively. However, when 25 GP is compared to 0 GP, its compressive strength is 9.88%, 16.25%, and 29.11% less at 7, 14 and 28 days, respectively. The decrease in the compressive strength of the ECC mixtures with the incorporation of GP can be attributed to the low reactivity of the GP which results in lower strength contributed to the toughness of the matrix. These results agree with that of Schwarz et al. [25] and Islam et al. [26] where they observed a decrease in the compressive strength of concrete incorporating GP as replacement of OPC.
cement-based materials are cast, they are in a plastic state. Hence, excessive evaporation of bleed water can lead to significant dimensional change referred to as plastic shrinkage. When the cementitious material is subjected to no restraints, the resulting plastic shrinkage is referred to as unrestrained or free plastic shrinkage. The change in length due to free plastic shrinkage of the evaluated ECC mixtures with time is presented in Fig. 7 while the cumulative length change is shown in Fig. 8. It is found from Fig. 7 that the rate and length change of 0 GP is significantly higher when compared to ECC mixtures incorporating GP. Similarly, observing the cumulative length change presented in Fig. 8, the shrinkage of 25 GP and 50 GP is 81.9% and 82.7% lower than that of the ECC mixture with no GP (i.e. 0 GP), respectively. The lower plastic shrinkage of ECC mixtures incorporating GP can be attributed to possible excess bleed water available because of the lower reactivity of the GP.
3.2. Shrinkage properties 3.2.1. Free plastic shrinkage Cement-based materials undergo dimensional change when in plastic and dried state. Within the first few hours after the
Fig. 7. Plastic shrinkage of ECC mixtures.
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Fig. 8. Change in length of ECC mixtures due to plastic shrinkage after 4 h.
3.2.2. Autogenous shrinkage Cementitious composites with low water to binder ratio are poised with higher autogenous shrinkage which is a result of the cementitious matrix undergoing self desiccation. In contrast to the drying shrinkage, autogenous shrinkage is a result of the hydration and pozzolanic reaction within the cementitious matrix. The autogenous shrinkage of the ECC mixtures evaluated is presented in Fig. 9. It can be observed that similar to the plastic shrinkage, the autogenous shrinkage of the ECC mixtures reduces with the incorporation of GP. However, for all mixtures, the shrinkage becomes almost stabilized after 15 days (i.e. approximately 2 weeks) which indicates that most hydration products have been formed within the first two weeks. Fig. 10 presents the cumulative autogenous shrinkage of the ECC mixture at 28 days. It is seen from Fig. 10 that the autogenous shrinkage of ECC mixtures can be reduced significantly with the use of higher GP content. The shrinkage of 25 GP and 50 GP is 13.6% and 73.0% lower when compared to that of 0 GP. Autogenous shrinkage occurs as a result of the consumption of water by the cement for hydration. The lower autogenous shrinkage of 25 GP and 50 GP can be attributed to the lower proportion of cementitious component consuming the free water thereby resulting in lower shrinkage of the mixtures.
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Fig. 10. Autogenous shrinkage of ECC mixtures at 28 days.
3.2.3. Drying shrinkage The possible application of ECC mixtures evaluated in this study as a new construction or repair material for pavements, slabs, floors, bridge decks, etc., has called for a need to evaluate its drying
shrinkage. Generally, thin structural elements with large surface area made with cementitious materials are prone to a higher shrinkage due to drying. The use of fibres to reinforce cementitious materials is one of the effective ways to mitigate its drying shrinkage [27]. However, the absence of coarse aggregate in ECC mixtures has posed an imminent need to evaluate the drying shrinkage of ECC mixtures incorporating novel materials. The drying shrinkage of the ECC mixtures evaluated is presented in Fig. 11 and the cumulative length change at the end of 28 days presented in Fig. 12. It can be found from Fig. 11 that similar to the autogenous shrinkage, the incorporation of GP into the ECC mixtures led to a decrease in drying shrinkage. As presented in Fig. 12, the shrinkage of 25 GP and 50 GP is 22.9% and 41.2% lower than that of 0 GP, respectively. The lower drying shrinkage of ECC mixtures incorporating GP can be attributed to the possible cement dilution effect as a result of the GP added to the mixture. This observation corresponds with that of Lu et al. [28] where they observed decreased in the drying shrinkage of mortar incorporating GP, and also verify the results with the heat of hydration. Similarly, Bazhuni et al. [34] and Sharifi et al. [35] observed a decrease in the drying shrinkage of cement paste with the introduction of glass powder into the mixture. One of the main factors responsible for drying shrinkage is the loss of free water from the capillary pores. Hence, it is anticipated that there would be a relationship between the shrinkage and reduction in mass of the specimens. It is interesting to see that in contrast to the shrinkage of the mixtures, the ECC mixtures with GP exhibited a higher mass loss due to drying shrinkage when
Fig. 9. Autogenous shrinkage of ECC mixtures.
Fig. 11. Drying shrinkage of ECC mixtures.
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Fig. 12. Drying shrinkage of ECC mixtures at 28 days. Fig. 14. Porosity of ECC mixtures.
compared to the mixture with no GP. This behaviour of ECC mixtures incorporating GP can be attributed to its less densified microstructure which allows easy movement of free water out of the composite. Nevertheless, there exists a strong correlation between the loss of mass and drying shrinkage of all mixtures as shown in Fig. 13. The porosity observed in this study (Fig. 14) (i.e. less than 18%) is slightly lower compared to their study and this is possibly due to the absence of coarse aggregate in ECC mixtures. The slight increase in the porosity with the introduction of the GP compared to the control ECC mixture can be attributed to the delayed pozzolanic reaction of the GP. 3.3. Water absorption The water absorption of the three ECC mixtures evaluated is presented in Fig. 15. It can be found from Fig. 15 that similar to the porosity of the ECC mixtures, the absorption increases with the introduction of GP into the mixtures. The increase in absorption with GP content can be attributed to the increased porosity due to the slow reactivity of the GP. This observation agrees with that of Letelier et al. (2019) [36] where they observed increase in the absorption with increasing content of glass powder as a replacement of cement in concrete mixtures Evaluating the correlation between the porosity and absorption, it is observed from Fig. 16 that there is a linear relationship between the absorption and porosity of the ECC mixtures. These results show that the increase in porosity of ECC mixtures incorporating GP creates more pathways for the movement of water into the composite.
Fig. 15. Absorption of ECC mixtures.
Fig. 16. Correlation between porosity and absorption of ECC mixtures.
Fig. 13. Correlation between drying shrinkage and mass loss of ECC specimens.
3.4. Sorption Moisture can penetrate cementitious composites through diffusion, or permeation or sorption (i.e. capillary absorption). As most cementitious composites remain unsaturated throughout their service life, moisture penetration through sorption is the most significant one and can be used to evaluate the durability of the composites. The sorption of the ECC mixtures evaluated is presented in Fig. 17. It is observed from this figure that similar to the absorption and porosity results, the sorption of the ECC
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Fig. 17. Sorption of ECC mixtures.
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Fig. 18. Chloride ion permeability of ECC mixtures.
mixtures increased with the introduction of GP in the mixture. The reason for this behaviour can be attributed to the same reason as that of the absorption (i.e. increase in porosity). The observations in this study contradict that of Nassar and Soroushian [29] where they reported a reduction in the sorption of mortars incorporating glass powder. 3.5. Sorptivity The rate of absorption of water (i.e. sorptivity) of cement-based materials is a good indication of its susceptibility to water penetration. The resulting absorption and sorptivity of the mixtures are presented in Table 4. It can be observed from Table 4 that the incorporation of GP into the ECC mixtures does not have any significant effects on the rate of absorption of the ECC. However, there is a slight increase in the absorption of the ECC mixtures with increasing GP content. These observations agree with that of Liu [30] where they observed a slight increase in the absorption of concrete mixtures incorporating ground glass. The absorption depth of all the mixtures is approximately 2.55 mm, while the corresponding sorptivity is 0.003 mm/s1/2. This lower sorptivity observed for all mixtures can be attributed to the high content of FA used which serves as a filler to densify the microstructure of the composite at an early age. Similar sorptivity observed in all mixtures corresponds strongly to the observation made by Matos and SousaCoutinho [31] where no significant difference was observed in the sorptivity of mortar mixtures incorporating GP when compared to that of the control. 3.6. Chloride ion penetration The ease at which chloride ion can penetrate into cement-based materials is a good indication of its overall durability. The chloride ion penetration of the ECC mixtures in this study was evaluated using a rapid chloride penetration (RCP) test. The results of the chloride penetration are expressed in terms of the total charge passed at the end of the test in accordance with ASTM C 1202. The results from the RCP test of the three mixtures are presented in Fig. 18. The values presented in Fig. 18 is the total charge passed after the specimens were subjected to 60 V direct current for 6 h. It is observed from Fig. 18 that the total charge passed in the ECC
Table 4 Absorption and sorptivity of ECC mixtures. Mixture ID
Absorption (mm)
Sorptivity (mm/s1/2)
0 GP 25 GP 50 GP
2.546 2.549 2.558
0.003 0.003 0.003
Fig. 19. Correlation between porosity and chloride ion permeability of ECC mixtures.
Fig. 20. Expansion due to ASR of ECC mixtures.
mixtures increased with increasing GP content. The total charged passed for 25 GP and 50 GP is 8.2% and 27.1% higher than that of 0 GP. The higher charge passed for ECC mixtures incorporating GP can be attributed to the slow pozzolanic reactivity of the GP particles and higher porosity as presented in the correlation shown in Fig. 19. The increase in porosity with the incorporation of GP creates an easy path for the chloride ions to flow through the composite. Nevertheless, since the total charged in 25 GP and 50 GP is
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Fig. 21. EDS analysis of (a) FA (b) GP.
Fig. 22. Microstructure of (a) 0 GP (b) 50 GP.
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Compared to other properties, the RCP test results observed for these ECC mixtures correspond to those made by Siad et al. [32] where they recorded an increase in the total charge passed with increasing content of GP in ECC mixtures. On the contrary, Schwarz and Neithalath [11] reported a decrease in the chloride ion penetration of concrete mixtures incorporating glass powder when compared to the control without it. 3.7. Alkali-silica reaction
Fig. 23. Microstructure of 50 GP after exposure to high temperature and alkali solution.
between 2000 and 4000 Coulombs, the ion permeability of the mixtures can be classified as moderate according to ASTM C 1202. This observation shows that the ECC mixtures containing GP can be used in similar applications where conventional ECC mixtures are used.
The use of glass as any component in cement-based materials has always been a course of concern due to the high alkalinity of the pore solution of cementitious materials and high silica content in the glass. The interaction between the alkalis from the pore solution with the high silica content in glass can cause a detrimental reaction called alkali-silica reaction. In order to evaluate the alkali resistance of the ECC mixtures in this study, the accelerated bar test in accordance with ASTM C 1260 was used. The percentage expansion of the three ECC mixtures evaluated is presented in Fig. 20. It can be observed from Fig. 20 that no detrimental expansion occurs in any of the specimens even that with a high content of GP (i.e. 50 GP) at 28 days. The ECC mixtures experienced shrinkage instead of expansion which might be attributed to self desiccation of the cementitious matrix. The absence of expansion in these mixtures can be attributed to the lower grain size of GP in addition to the high fly ash content used. This observation corresponds strongly with that of Jin et al. [33] and Shayan and Xu [15] where they found that finer glass particle size does not pose any detrimental threat to the durability integrity of concrete mixtures in terms of its susceptibility to ASR. A similar observation was also
Area 1
(a) Area 1
(b) Fig. 24. EDS spectrum of hydration products obtained from Area 1 in (a) 50 GP (b) 50 GP exposed to high alkali and temperature.
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made by Zheng [37] and Schwarz et al. [38] where they reported glass powder suppressed the expansions in concrete mixtures incorporating glass powder instead of causing an expansion.
3.8. Microstructural analysis To evaluate the effect of GP on the microstructural properties of ECC mixtures, scanning electron microscopy (SEM) images were obtained and EDS analyses were carried out on the mixtures. The EDS analyses of the elements present in FA and GP are shown in Fig. 21. Fig. 22 presents the SEM images of 0 GP and 50 GP. It can be observed from Fig. 22 that the hydration products are well bonded to the PVA fibre. The SEM image of 50 GP exposed to high temperature (80 °C) and alkali environment is presented in Fig. 23. It is observed that compared to the SEM image of 50 GP in Fig. 22 there seems to be some distortion in the microstructure of 50 GP exposed to the severe environment (Fig. 23). The distortion in the microstructure is a result of the combined effect of the high temperature and alkali. Nevertheless, no expansion was observed in the specimens subjected to this severe temperature. To have more understanding of the microstructure properties of the ECC mixtures, EDS analysis was carried out on the hydration products in 50 GP exposed to normal curing conditions and that exposed to severe conditions and the resulting spectrums presented in Fig. 24. It can be observed from Fig. 24 that the chemical composition of 50 GP exposed to the aggressive environment remains relatively stable. However, the lower intensity of the element presence might be attributed to the location which was selected for the analysis.
4. Conclusions This study has experimentally evaluated the durability performance of ECC mixtures incorporating GP as a binder. Based on the outcome of this study, the following conclusions can be drawn: 1. The incorporation of GP as binder into ECC mixtures reduces the plastic, autogenous, and drying shrinkage of ECC mixtures, which further reduces with increasing GP content. This favourable effect can be attributed to the dilution effect of the GP which led to a reduction in the hydration degree of the ECC mixtures. 2. The use of GP in ECC mixtures resulted in an increase in the permeability properties. However, the permeability properties of 25 GP are similar to that of 0 GP, this shows that the use of 25% GP as partial replacement of fly ash in ECC mixtures is the optimum. Therefore, ECC mixtures incorporating 25% GP as partial replacement of fly ash can still be utilized for practical applications without any significant detrimental effect on its durability properties. 3. No sign of alkali-silica reaction was observed in all mixtures despite the use of glass in a cementitious composite. The absence of this deleterious reaction in the ECC mixtures evaluated has been attributed to the lower particle size of the GP which is less than 300 mm. Compared to limited previous works on the incorporation of GP into ECC mixtures, this study extensively experimentally evaluates the durability properties of ECC mixtures in terms of its shrinkage properties, permeability properties and resistance to alkali-silica reaction. It would be of great interest to carry out future works on the performance of ECC mixtures incorporating glass as both binder and aggregates.
CRediT authorship contribution statement Adeyemi Adesina: Conceptualization, Methodology, Investigation, Formal analysis, Visualization, Writing - original draft. Sreekanta Das: Conceptualization, Validation, Writing - review & editing, Supervision, Funding acquisition, Resources. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgement The authors acknowledge the Natural Sciences and Engineering Research Council of Canada for the financial support provided. References [1] V.C. Li, Interface tailoring for strain-hardening polyvinyl alcohol-engineered cementitious composite (PVA-ECC), ACI Mater. J. 99 (5) (2002) 463–472. [2] M.D. Lepech, V.C. Li, Water permeability of engineered cementitious composites, Cem. Concr. Compos. 31 (2009) 744–753. [3] N.M. Altwair, M.A.M. Johari, S.F.S. Hashim, Influence of treated palm oil fuel ash on compressive properties and chloride resistance of engineered cementitious composites, Mater. Struct. Constr. 47 (4) (2014) 667–682. [4] V.C. Li, Tailoring ECC for special attributes: a review, Int. J. Concr. Struct. Mater. 6 (3) (2012) 135–144. [5] V.C. Li, S. Wang, C. Wu, Tensile strain-hardening behavior or polyvinyl alcohol engineered cementitious composite (PVA-ECC), ACI Mater. J. 98 (6) (2001) 483–492. [6] E. Özbay, O. Karahan, M. Lachemi, K.M.A. Hossain, Atisß C. Duran, Investigation of properties of engineered cementitious composites incorporating high volumes of fly ash and metakaolin, ACI Mater. J. 109 (5) (2012) 565–572. [7] M. Batayneh, I. Marie, I. Asi, Use of selected waste materials in concrete mixes, Waste Manage. 27 (12) (2007) 1870–1876. [8] T.C. Ling, C.S. Poon, A comparative study on the feasible use of recycled beverage and CRT funnel glass as fine aggregate in cement mortar, J. Clean Prod. 29 (2012) 46–52. [9] M. Mageswari, D.B. Vidivelli, The use of sheet glass powder as fine aggregate replacement in concrete, Open Civ. Eng. J. 4 (2010) 65–71. [10] P. Penacho, J. De Brito, M. Rosário Veiga, Physico-mechanical and performance characterization of mortars incorporating fine glass waste aggregate, Cem. Concr. Compos. 50 (2014) 47–59. [11] N. Schwarz, N. Neithalath, Influence of a fine glass powder on cement hydration: comparison to fly ash and modeling the degree of hydration, Cem. Concr. Res. 45 (2008) 39–45. [12] M. Carsana, M. Frassoni, L. Bertolini, Comparison of ground waste glass with other supplementary cementitious materials, Cem. Concr. Compos. 45 (2014) 39–45. [13] Y. Jani, W. Hogland, Waste glass in the production of cement and concrete – A review, J. Environ. Chem. Eng. 2 (3) (2014) 1767–1775. [14] A. Khmiri, M. Chaabouni, B. Samet, Chemical behaviour of ground waste glass when used as partial cement replacement in mortars, Constr. Build. Mater. 44 (2013) 74–80. [15] A. Shayan, A. Xu, Value-added utilisation of waste glass in concrete, Cem. Concr. Res. 34 (1) (2004) 81–89. [16] H. Siad, M. Lachemi, M. Sahmaran, H.A. Mesbah, K.M.A. Hossain, Use of recycled glass powder to improve the performance properties of high volume fly ash-engineered cementitious composites, Constr. Build. Mater. 163 (2018) 53–62. [17] H. Siad, M. Lachemi, M. Sahmaran, K.M.A. Hossain, Mechanical, physical, and self-healing behaviors of engineered cementitious composites with glass powder, J. Mater. Civ. Eng. 29 (6) (2017) 1–12. [18] ASTM C109. Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [ 50-mm ] Cube Specimens) 1. Chem. Anal. 2010; (C109/C109M – 11b), 1–9. [19] E. Booya, K. Gorospe, H. Ghaednia, S. Das, Free and restrained plastic shrinkage of cementitious materials made of engineered kraft pulp fibres, Constr. Build. Mater. 212 (2019) 236–246. [20] ASTM C 642-2006, Standard test method for density, absorption, and voids in hardened concrete 4 (2006) 1–3. [21] ASTM C1757, ASTM Standard C1757 – Standard Test Method for Determination of One-Point, Bulk Water Sorption of Dried Concrete, ASTM Int., 2014, pp. 14–16. [22] ASTM C1585, Standard Test Method for Mesurement of Rate Absorption of Water by Hydraulic-Cement Concretes, Annu B ASTM Stand [Internet] 04 (147) (2004) 1–6.
A. Adesina, S. Das / Construction and Building Materials 242 (2020) 118199 [23] Drilled T, Concrete C, Statements B, Speci- CCT, Cores TD, Test CC. Standard Test Method for Electrical Indication of Concrete’s Ability to Resist Chloride. 1986;i(95 mm):1–6. [24] ASTM C1260-Standard test method for potential alkali reactivity of aggregates (mortar-bar method) ASTM Int. [Internet] 2012; 1–5. [25] N. Schwarz, H. Cam, N. Neithalath, Influence of a fine glass powder on the durability characteristics of concrete and its comparison to fly ash, Cem. Concr. Compos. 30 (6) (2008) 486–496. [26] G.M.S. Islam, M.H. Rahman, N. Kazi, Waste glass powder as partial replacement of cement for sustainable concrete practice, Int. J. Sustain Built. Environ. 6 (1) (2017) 37–44. [27] N. Yousefieh, A. Joshaghani, E. Hajibandeh, M. Shekarchi, Influence of fibers on drying shrinkage in restrained concrete, Constr. Build. Mater. 148 (1) (2017) 833–845. [28] J.X. Lu, B.J. Zhan, Z.H. Duan, C.S. Poon, Using glass powder to improve the durability of architectural mortar prepared with glass aggregates, Mater. Des. 135 (2017) 102–111. [29] R.-U.-D. Nassar, P. Soroushian, Green and durable mortar produced with milled waste glass, Mag. Concr. Res. 64 (7) (2012) 605–615. [30] M. Liu, Incorporating ground glass in self-compacting concrete, Constr. Build. Mater. (2011). [31] A.M. Matos, J. Sousa-Coutinho, Durability of mortar using waste glass powder as cement replacement, Constr. Build. Mater. 36 (2012) 205–215.
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[32] H. Siad, M. Lachemi, M. Sahmaran, H.A. Mesbah, K.M. Anwar, Use of recycled glass powder to improve the performance properties of high volume fly ash-engineered cementitious composites, Constr. Build. Mater. 163 (2018) 53–62. [33] W. Jin, C. Meyer, S. Baxter, ‘‘Glascrete” – Concrete with glass aggregate, ACI Struct. J. 97 (2) (2000) 208–213. [34] M. Bazhuni, M. Kamali, A. Ghahremaninezhad, An investigation into the properties of ternary and binary cement pastes containing glass powder, Front. Struct. Civ. Eng. 13 (3) (2019) 741–750. [35] Y. Sharifi, I. Afshoon, Z. Firoozjaei, A. Momeni, Utilization of waste glass microparticles in producing self-consolidating concrete mixtures, Int. J. Concr. Struct. Mater. (2016), https://doi.org/10.1007/s40069-016-0141-z. [36] V. Letelier, B. Henríquez-Jara, M. Manosalva, M. Parodi, J. Ortega, Use of waste glass as a replacement for raw materials in mortars with a lower environmental impact, Energies 2019 (1974) 12, https://doi.org/10.3390/ en12101974www.mdpi.com/journal/energies. [37] K. Zheng, Pozzolanic reaction of glass powder and its role in controlling alkalisilica reaction, Cem. Concr. Compos. 67 (2016) 30–38. [38] N. Schwarz, H. Cam, N. Neithalath, Influence of a fine glass powder on the durability characteristics of concrete and its comparison to fly ash, Cem. Concr. Compos. 30 (6) (2008) 486–496.
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Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Influence of glass powder on the durability properties of engineered cementitious composites Adeyemi Adesina, Sreekanta Das ⇑ Department of Civil and Environmental Engineering, University of Windsor, Windsor, Ontario, Canada
h i g h l i g h t s Glass powder was used to partially replace the binder component in ECC up to 50%. Alkali-silica reaction, shrinkage and permeability of the ECC was evaluated. Microstructural properties of mixtures was investigated. No trace of alkali-silica reaction in the ECC mixtures.
a r t i c l e
i n f o
Article history: Received 14 August 2019 Received in revised form 6 January 2020 Accepted 14 January 2020
Keywords: Engineered cementitious composite (ECC) Glass powder Durability Green material Microstructure
a b s t r a c t This paper presents outcomes of investigation on various durability properties of engineered cementitious composites (ECC) incorporating glass powder as the cementitious material. The Durability was evaluated by assessing the shrinkage, permeability, and alkali-silica reaction resistance of the ECC mixtures. Shrinkage properties investigated are plastic, autogenous and drying shrinkage. The permeability properties evaluated are porosity, water absorption, sorption, sorptivity and chloride ion penetration. Results from this study showed that glass powder can be used to significantly reduce the shrinkage of ECC mixtures, however, there is a negative effect on its permeability properties. On the positive side, no occurrence of the alkali-silica reaction was observed in any ECC mixtures incorporating glass powder. Based on the overall performance of ECC mixtures incorporating glass powder, the replacement of 25% fly ash with glass powder was found to be the optimum. Ó 2020 Elsevier Ltd. All rights reserved.
1. Introduction The last decade has seen a rapid enhancement and development of various cementitious composites. One of the promising cementitious composites developed in the last decade is called engineered cementitious composite (ECC), and the termed ‘‘engineered” in ECC is coined based on the micromechanics design in which the composite is based [1]. ECC has superior performance when compared to conventional concrete. The strain capacity of ECC is several hundred times larger than that of regular cement concrete, and its crack width usually less than 60 mm equipped the composite with enhanced mechanical and durability properties [2]. In order to achieve the higher tensile capacity and lower permeability, higher content of fly ash (FA) in the range of 1.2–4.2 times Portland cement (PC) is used in conventional ECC mixtures [3–6]. ⇑ Corresponding author. E-mail addresses: [email protected] (A. Adesina), [email protected] (S. Das). https://doi.org/10.1016/j.conbuildmat.2020.118199 0950-0618/Ó 2020 Elsevier Ltd. All rights reserved.
As the world is becoming more sustainability conscious, the supply of FA is expected to reduce significantly in the coming years especially in developed countries like the USA and Canada due to the rapid decommissioning of coal-powered plants. Therefore, it is paramount to find alternative materials that can be used to partially or totally replace FA in ECC mixtures. One of the wastes generated in large quantities and less incorporated into ECC mixtures is glass wastes. Glass wastes have been used extensively used in ordinary Portland cement (OPC) concrete mixtures as aggregate and/or replacement of OPC depending on its size [7–11]. However, its application in ECC mixture is very limited. Therefore, in order to further improve the sustainability of ECC while conserving the supply of FA, recycled glass in form of powder (i.e. glass powder) can be used in ECC mixtures. Glass powder (GP) can be incorporated into cementitious materials as partial replacement of the binders due to its pozzolanic properties [11–14]. However, it is worth to mention that its pozzolanic reaction is slower when compared to that of FA [11,12,14,15]. Siad et al. [16] were able to use glass powder up to 60% to replace FA in ECC mixtures, however, only the chloride permeability and the electrical resistivity were the
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durability properties assessed. In order to fully utilize GP in ECC mixtures, it is paramount to evaluate other durability properties of the cementitious composite especially its shrinkage, permeability and resistance to deleterious reactions such as alkali-silica reaction. Though the study by Siad et al. [17] showed that GP can replace FA totally in ECC, a preliminary study by the authors to evaluate the effect of GP on the mechanical properties of ECC mixtures showed that only the use of GP up to 1.1 times the OPC or 50% replacement of FA is practical to produce a structural grade ECC. Also, it is worth to mention that the ECC mixtures evaluated in this study are intended to be used as a construction or repair material for pavements. Therefore, this study was designed and undertaken to investigate the effect of glass powder (GP) used up to 50% replacement of FA in ECC mixtures on its durability properties. Durability properties evaluated include plastic shrinkage, autogenous shrinkage, drying shrinkage, porosity, water absorption, sorption, sorptivity, chloride ion penetration and alkali-silica reaction. The microstructural investigation was also carried by obtaining scanning electron microscopy (SEM) images and carrying out energy-dispersive Xray spectroscopy (EDS) analysis. 2. Experimental program
Details about the ECC mixtures evaluated in this study are presented in Table 3. The ratio between the FA and GP was kept unchanged at 2.2 by mass of the PC for all mixtures, and the water to binder ratio was maintained at 0.25. The mixture ID indicated in Table 3 represents the proportion of GP used as a percentage of the FA content. For example, the 25 GP and 50 GP indicate 25% and 50% replacement of the FA with GP respectively.
2.2. Mixing and curing All mixtures were prepared using a 70 L Hobart mixer. The binder (i.e. OPC, FA and GP) and aggregates were first dry mixed for 2 min, followed by the addition of water premixed with SP were then added to the mixture and mixed for another 2 min. Oil coated PVA fibres are then slowly added to the mixture and mixed for an additional 2 min. Immediately after mixing, the fresh mixtures were placed in different moulds associated with the tests to be carried out and covered with a plastic sheet to avoid loss of moisture or as required by the test method. After approximately 24 h after casting, the specimens were demoulded and cured under water till the testing age or as required by the test procedure.
2.3. Test methods 2.3.1. Compressive strength Compressive strength was carried out in accordance with ASTM C 109 [18] on cube specimens with a dimension of 50 mm 50 mm 50 mm. For each mixture, four specimens were evaluated, and the average compressive strength was determined.
2.1. Materials and mixture proportion Type 1 Portland cement (PC) alongside ASTM class F fly ash (FA) and glass powder (GP) was used as the binder in this study. The properties of the binders are presented in Table 1 and the SEM image of FA and GP are shown in Fig. 1. Micro-silica sand (SS) was used as aggregate and polyvinyl alcohol (PVA) fibres with properties presented in Table 2 were used to reinforce the ECC mixtures. To improve the interfacial properties between the fibre and the cementitious matrix, the PVA fibre used in this study had a coating with an oiling agent (at 1.2% by weight). In order to achieve excellent workability, an equal dosage of superplasticizer (SP) was used for all mixtures. Table 1 Chemical composition of binders and aggregate (%). Compound
PC
FA
GP
SS
CaO SiO2 Al2O3 Fe2O3 SO3 Na2O LOI
62.43 19.78 5.38 2.67 3.47 0.12 1.52
1.33 61.3 19.91 6.9 0.28 1.02 3.65
8.07 67.37 4.79 – – 14.81 0.4
19.17 46.65 6.6 3.07 – 1.13 –
2.3.2. Free plastic shrinkage The free plastic shrinkage of the ECC mixtures was evaluated using the test procedure similar to that of Booya et al. [19]. The test procedure entails using the environmental chamber with schematics shown in Fig. 2, and the mould setup presented in Fig. 3. The change in length of the mixtures captured by a linear variable differential traducer (LVDT) within the first four hours was used to assess the plastic shrinkage of the mixtures. The need the put the mould in the environmental chamber is necessary to accelerate the rate of water evaporation from the ECC mixtures.
2.3.3. Autogenous and drying shrinkage Immediately after mixing, four bar specimens with dimensions of 25 mm 25 mm 250 mm were cast with two copper studs embedded at the ends for the length change measurements. At approximately 24 h, the specimens were demoulded and cured in water for 24 h. Then the specimens were stored in the laboratory with ambient temperature and relative humidity (i.e. 25 ± 2 °C and 50 ± 5% RH respectively) for drying shrinkage. For autogenous shrinkage, the specimens were wrapped with aluminum foil and tape immediately after demoulding. Then these specimens were stored in the laboratory. Changes in length of each bar specimen in all mixtures for both autogenous and drying shrinkages were measured up to 28 days. The shrinkage of the mixtures was determined based on the change in length of the specimens compared to the initial length taken before the specimens were exposed to drying conditions.
Fig. 1. SEM image of (a) FA (b) GP.
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A. Adesina, S. Das / Construction and Building Materials 242 (2020) 118199 Table 2 Properties of PVA fibre. Length (mm)
Diameter (mm)
Tensile strength (MPa)
Young Modulus (GPa)
Elongation (%)
8
40
1600
41
6
Table 3 Mixture proportion (in ratio to PC). Mixture ID
PC
FA
GP
Sand/Binder
Water/Binder
SP
Fiber (% Vol.)
0 GP 25 GP 50 GP
1 1 1
2.2 1.6 1.1
0 0.6 1.1
0.38 0.38 0.38
0.25 0.25 0.25
0.015 0.015 0.015
2 2 2
Fig. 2. Schematics of plastic shrinkage setup.
Fig. 3. Mould setup for plastic shrinkage. 2.3.4. Porosity and water absorption The porosity (i.e. % voids) and absorption of each mixture were evaluated according to ASTM C 642 [20] test procedures. This test was carried out on cylindrical specimens with a diameter of 100 mm and a height of 50 mm. The porosity of the ECC mixtures was obtained from the resulting bulk density and apparent density, while the absorption was calculated based on the mass of the specimen after oven drying and immersion in water. 2.3.5. Sorption The bulk water sorption of the ECC mixtures was evaluated in accordance with ASTM C 1757 [21]. This test method uses the amount of water absorbed into cementitious composite within 30 min to evaluate the overall durability of the composite. Cylindrical specimens with 100 mm diameter and 50 mm height were first dried in the oven at 50 °C for approximately 48 h, followed by cooling down at room temperature for approximately 24 h. After the specimens have cooled down, they were fully immersed in water for 30 min and the sorption calculated based on the amount of water absorbed calculated from the mass change of the specimens. 2.3.6. Sorptivity The rate of water absorption (i.e. sorptivity) of the ECC mixtures was evaluated in accordance with the procedure in ASTM C 1585 [22]. In contrast to the sorption test (i.e. ASTM C 1757), the capillary water is retained in the pores. This test was
used to evaluate the rate at which water penetrates into an unsaturated specimen. Cylindrical specimens with a height of 100 mm and a diameter of 50 mm were conditioned and evaluated using the guidelines and procedures in ASTM C 1585. A schematic of the test setup for the absorption and sorptivity of the ECC mixtures is presented in Fig. 4.
2.3.7. Chloride ion penetration test This test was carried out in accordance with ASTM C 1202 [23] on cylindrical specimens with a diameter of 100 mm and 50 mm height. The cylindrical specimens were placed between 0.3 M NaOH and 3% solution and 60-V applied across as depicted in Fig. 5. The current passing through the setup was recorded using a data acquisition system, and the total charge for each mixture obtained from the average of two specimens evaluated for each mixture.
2.3.8. Alkali-silica reaction The incorporation of GP into ECC mixtures has called for a need to evaluate the resistance of the mixtures to alkali-silica reaction (ASR). The evaluation was carried out in accordance with ASTM C 1260 [24]. The test method entails soaking bar specimens with a dimension of 25 mm 25 mm 250 mm in 1 M NaOH and subjecting it to a temperature of 80 °C. The resistance of the mixtures was assessed based on the expansion measured in terms of length change of the specimens.
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Fig. 4. Test setup for sorptivity.
Fig. 6. Compressive strength of ECC mixtures at different ages. Fig. 5. Test setup for chloride ion penetration test. 2.3.9. Microstructural analysis The microstructural investigation was carried out on the ECC mixtures by using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). SEM was used to obtain microstructure images, and EDS was used to carry out the elemental analysis.
3. Results and discussion 3.1. Compressive strength The compressive strength of the ECC mixtures at different ages is presented in Fig. 6. It can be observed from Fig. 6 that the compressive strength of all the ECC mixtures increased with age, however, it reduced with increasing GP content. For example, the compressive strength of 25 GP at 7 days is 22.8 MPa, while at 14 and 28 days it was 30.4 and 35.8 MPa, respectively. However, when 25 GP is compared to 0 GP, its compressive strength is 9.88%, 16.25%, and 29.11% less at 7, 14 and 28 days, respectively. The decrease in the compressive strength of the ECC mixtures with the incorporation of GP can be attributed to the low reactivity of the GP which results in lower strength contributed to the toughness of the matrix. These results agree with that of Schwarz et al. [25] and Islam et al. [26] where they observed a decrease in the compressive strength of concrete incorporating GP as replacement of OPC.
cement-based materials are cast, they are in a plastic state. Hence, excessive evaporation of bleed water can lead to significant dimensional change referred to as plastic shrinkage. When the cementitious material is subjected to no restraints, the resulting plastic shrinkage is referred to as unrestrained or free plastic shrinkage. The change in length due to free plastic shrinkage of the evaluated ECC mixtures with time is presented in Fig. 7 while the cumulative length change is shown in Fig. 8. It is found from Fig. 7 that the rate and length change of 0 GP is significantly higher when compared to ECC mixtures incorporating GP. Similarly, observing the cumulative length change presented in Fig. 8, the shrinkage of 25 GP and 50 GP is 81.9% and 82.7% lower than that of the ECC mixture with no GP (i.e. 0 GP), respectively. The lower plastic shrinkage of ECC mixtures incorporating GP can be attributed to possible excess bleed water available because of the lower reactivity of the GP.
3.2. Shrinkage properties 3.2.1. Free plastic shrinkage Cement-based materials undergo dimensional change when in plastic and dried state. Within the first few hours after the
Fig. 7. Plastic shrinkage of ECC mixtures.
A. Adesina, S. Das / Construction and Building Materials 242 (2020) 118199
Fig. 8. Change in length of ECC mixtures due to plastic shrinkage after 4 h.
3.2.2. Autogenous shrinkage Cementitious composites with low water to binder ratio are poised with higher autogenous shrinkage which is a result of the cementitious matrix undergoing self desiccation. In contrast to the drying shrinkage, autogenous shrinkage is a result of the hydration and pozzolanic reaction within the cementitious matrix. The autogenous shrinkage of the ECC mixtures evaluated is presented in Fig. 9. It can be observed that similar to the plastic shrinkage, the autogenous shrinkage of the ECC mixtures reduces with the incorporation of GP. However, for all mixtures, the shrinkage becomes almost stabilized after 15 days (i.e. approximately 2 weeks) which indicates that most hydration products have been formed within the first two weeks. Fig. 10 presents the cumulative autogenous shrinkage of the ECC mixture at 28 days. It is seen from Fig. 10 that the autogenous shrinkage of ECC mixtures can be reduced significantly with the use of higher GP content. The shrinkage of 25 GP and 50 GP is 13.6% and 73.0% lower when compared to that of 0 GP. Autogenous shrinkage occurs as a result of the consumption of water by the cement for hydration. The lower autogenous shrinkage of 25 GP and 50 GP can be attributed to the lower proportion of cementitious component consuming the free water thereby resulting in lower shrinkage of the mixtures.
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Fig. 10. Autogenous shrinkage of ECC mixtures at 28 days.
3.2.3. Drying shrinkage The possible application of ECC mixtures evaluated in this study as a new construction or repair material for pavements, slabs, floors, bridge decks, etc., has called for a need to evaluate its drying
shrinkage. Generally, thin structural elements with large surface area made with cementitious materials are prone to a higher shrinkage due to drying. The use of fibres to reinforce cementitious materials is one of the effective ways to mitigate its drying shrinkage [27]. However, the absence of coarse aggregate in ECC mixtures has posed an imminent need to evaluate the drying shrinkage of ECC mixtures incorporating novel materials. The drying shrinkage of the ECC mixtures evaluated is presented in Fig. 11 and the cumulative length change at the end of 28 days presented in Fig. 12. It can be found from Fig. 11 that similar to the autogenous shrinkage, the incorporation of GP into the ECC mixtures led to a decrease in drying shrinkage. As presented in Fig. 12, the shrinkage of 25 GP and 50 GP is 22.9% and 41.2% lower than that of 0 GP, respectively. The lower drying shrinkage of ECC mixtures incorporating GP can be attributed to the possible cement dilution effect as a result of the GP added to the mixture. This observation corresponds with that of Lu et al. [28] where they observed decreased in the drying shrinkage of mortar incorporating GP, and also verify the results with the heat of hydration. Similarly, Bazhuni et al. [34] and Sharifi et al. [35] observed a decrease in the drying shrinkage of cement paste with the introduction of glass powder into the mixture. One of the main factors responsible for drying shrinkage is the loss of free water from the capillary pores. Hence, it is anticipated that there would be a relationship between the shrinkage and reduction in mass of the specimens. It is interesting to see that in contrast to the shrinkage of the mixtures, the ECC mixtures with GP exhibited a higher mass loss due to drying shrinkage when
Fig. 9. Autogenous shrinkage of ECC mixtures.
Fig. 11. Drying shrinkage of ECC mixtures.
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Fig. 12. Drying shrinkage of ECC mixtures at 28 days. Fig. 14. Porosity of ECC mixtures.
compared to the mixture with no GP. This behaviour of ECC mixtures incorporating GP can be attributed to its less densified microstructure which allows easy movement of free water out of the composite. Nevertheless, there exists a strong correlation between the loss of mass and drying shrinkage of all mixtures as shown in Fig. 13. The porosity observed in this study (Fig. 14) (i.e. less than 18%) is slightly lower compared to their study and this is possibly due to the absence of coarse aggregate in ECC mixtures. The slight increase in the porosity with the introduction of the GP compared to the control ECC mixture can be attributed to the delayed pozzolanic reaction of the GP. 3.3. Water absorption The water absorption of the three ECC mixtures evaluated is presented in Fig. 15. It can be found from Fig. 15 that similar to the porosity of the ECC mixtures, the absorption increases with the introduction of GP into the mixtures. The increase in absorption with GP content can be attributed to the increased porosity due to the slow reactivity of the GP. This observation agrees with that of Letelier et al. (2019) [36] where they observed increase in the absorption with increasing content of glass powder as a replacement of cement in concrete mixtures Evaluating the correlation between the porosity and absorption, it is observed from Fig. 16 that there is a linear relationship between the absorption and porosity of the ECC mixtures. These results show that the increase in porosity of ECC mixtures incorporating GP creates more pathways for the movement of water into the composite.
Fig. 15. Absorption of ECC mixtures.
Fig. 16. Correlation between porosity and absorption of ECC mixtures.
Fig. 13. Correlation between drying shrinkage and mass loss of ECC specimens.
3.4. Sorption Moisture can penetrate cementitious composites through diffusion, or permeation or sorption (i.e. capillary absorption). As most cementitious composites remain unsaturated throughout their service life, moisture penetration through sorption is the most significant one and can be used to evaluate the durability of the composites. The sorption of the ECC mixtures evaluated is presented in Fig. 17. It is observed from this figure that similar to the absorption and porosity results, the sorption of the ECC
A. Adesina, S. Das / Construction and Building Materials 242 (2020) 118199
Fig. 17. Sorption of ECC mixtures.
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Fig. 18. Chloride ion permeability of ECC mixtures.
mixtures increased with the introduction of GP in the mixture. The reason for this behaviour can be attributed to the same reason as that of the absorption (i.e. increase in porosity). The observations in this study contradict that of Nassar and Soroushian [29] where they reported a reduction in the sorption of mortars incorporating glass powder. 3.5. Sorptivity The rate of absorption of water (i.e. sorptivity) of cement-based materials is a good indication of its susceptibility to water penetration. The resulting absorption and sorptivity of the mixtures are presented in Table 4. It can be observed from Table 4 that the incorporation of GP into the ECC mixtures does not have any significant effects on the rate of absorption of the ECC. However, there is a slight increase in the absorption of the ECC mixtures with increasing GP content. These observations agree with that of Liu [30] where they observed a slight increase in the absorption of concrete mixtures incorporating ground glass. The absorption depth of all the mixtures is approximately 2.55 mm, while the corresponding sorptivity is 0.003 mm/s1/2. This lower sorptivity observed for all mixtures can be attributed to the high content of FA used which serves as a filler to densify the microstructure of the composite at an early age. Similar sorptivity observed in all mixtures corresponds strongly to the observation made by Matos and SousaCoutinho [31] where no significant difference was observed in the sorptivity of mortar mixtures incorporating GP when compared to that of the control. 3.6. Chloride ion penetration The ease at which chloride ion can penetrate into cement-based materials is a good indication of its overall durability. The chloride ion penetration of the ECC mixtures in this study was evaluated using a rapid chloride penetration (RCP) test. The results of the chloride penetration are expressed in terms of the total charge passed at the end of the test in accordance with ASTM C 1202. The results from the RCP test of the three mixtures are presented in Fig. 18. The values presented in Fig. 18 is the total charge passed after the specimens were subjected to 60 V direct current for 6 h. It is observed from Fig. 18 that the total charge passed in the ECC
Table 4 Absorption and sorptivity of ECC mixtures. Mixture ID
Absorption (mm)
Sorptivity (mm/s1/2)
0 GP 25 GP 50 GP
2.546 2.549 2.558
0.003 0.003 0.003
Fig. 19. Correlation between porosity and chloride ion permeability of ECC mixtures.
Fig. 20. Expansion due to ASR of ECC mixtures.
mixtures increased with increasing GP content. The total charged passed for 25 GP and 50 GP is 8.2% and 27.1% higher than that of 0 GP. The higher charge passed for ECC mixtures incorporating GP can be attributed to the slow pozzolanic reactivity of the GP particles and higher porosity as presented in the correlation shown in Fig. 19. The increase in porosity with the incorporation of GP creates an easy path for the chloride ions to flow through the composite. Nevertheless, since the total charged in 25 GP and 50 GP is
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Fig. 21. EDS analysis of (a) FA (b) GP.
Fig. 22. Microstructure of (a) 0 GP (b) 50 GP.
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Compared to other properties, the RCP test results observed for these ECC mixtures correspond to those made by Siad et al. [32] where they recorded an increase in the total charge passed with increasing content of GP in ECC mixtures. On the contrary, Schwarz and Neithalath [11] reported a decrease in the chloride ion penetration of concrete mixtures incorporating glass powder when compared to the control without it. 3.7. Alkali-silica reaction
Fig. 23. Microstructure of 50 GP after exposure to high temperature and alkali solution.
between 2000 and 4000 Coulombs, the ion permeability of the mixtures can be classified as moderate according to ASTM C 1202. This observation shows that the ECC mixtures containing GP can be used in similar applications where conventional ECC mixtures are used.
The use of glass as any component in cement-based materials has always been a course of concern due to the high alkalinity of the pore solution of cementitious materials and high silica content in the glass. The interaction between the alkalis from the pore solution with the high silica content in glass can cause a detrimental reaction called alkali-silica reaction. In order to evaluate the alkali resistance of the ECC mixtures in this study, the accelerated bar test in accordance with ASTM C 1260 was used. The percentage expansion of the three ECC mixtures evaluated is presented in Fig. 20. It can be observed from Fig. 20 that no detrimental expansion occurs in any of the specimens even that with a high content of GP (i.e. 50 GP) at 28 days. The ECC mixtures experienced shrinkage instead of expansion which might be attributed to self desiccation of the cementitious matrix. The absence of expansion in these mixtures can be attributed to the lower grain size of GP in addition to the high fly ash content used. This observation corresponds strongly with that of Jin et al. [33] and Shayan and Xu [15] where they found that finer glass particle size does not pose any detrimental threat to the durability integrity of concrete mixtures in terms of its susceptibility to ASR. A similar observation was also
Area 1
(a) Area 1
(b) Fig. 24. EDS spectrum of hydration products obtained from Area 1 in (a) 50 GP (b) 50 GP exposed to high alkali and temperature.
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A. Adesina, S. Das / Construction and Building Materials 242 (2020) 118199
made by Zheng [37] and Schwarz et al. [38] where they reported glass powder suppressed the expansions in concrete mixtures incorporating glass powder instead of causing an expansion.
3.8. Microstructural analysis To evaluate the effect of GP on the microstructural properties of ECC mixtures, scanning electron microscopy (SEM) images were obtained and EDS analyses were carried out on the mixtures. The EDS analyses of the elements present in FA and GP are shown in Fig. 21. Fig. 22 presents the SEM images of 0 GP and 50 GP. It can be observed from Fig. 22 that the hydration products are well bonded to the PVA fibre. The SEM image of 50 GP exposed to high temperature (80 °C) and alkali environment is presented in Fig. 23. It is observed that compared to the SEM image of 50 GP in Fig. 22 there seems to be some distortion in the microstructure of 50 GP exposed to the severe environment (Fig. 23). The distortion in the microstructure is a result of the combined effect of the high temperature and alkali. Nevertheless, no expansion was observed in the specimens subjected to this severe temperature. To have more understanding of the microstructure properties of the ECC mixtures, EDS analysis was carried out on the hydration products in 50 GP exposed to normal curing conditions and that exposed to severe conditions and the resulting spectrums presented in Fig. 24. It can be observed from Fig. 24 that the chemical composition of 50 GP exposed to the aggressive environment remains relatively stable. However, the lower intensity of the element presence might be attributed to the location which was selected for the analysis.
4. Conclusions This study has experimentally evaluated the durability performance of ECC mixtures incorporating GP as a binder. Based on the outcome of this study, the following conclusions can be drawn: 1. The incorporation of GP as binder into ECC mixtures reduces the plastic, autogenous, and drying shrinkage of ECC mixtures, which further reduces with increasing GP content. This favourable effect can be attributed to the dilution effect of the GP which led to a reduction in the hydration degree of the ECC mixtures. 2. The use of GP in ECC mixtures resulted in an increase in the permeability properties. However, the permeability properties of 25 GP are similar to that of 0 GP, this shows that the use of 25% GP as partial replacement of fly ash in ECC mixtures is the optimum. Therefore, ECC mixtures incorporating 25% GP as partial replacement of fly ash can still be utilized for practical applications without any significant detrimental effect on its durability properties. 3. No sign of alkali-silica reaction was observed in all mixtures despite the use of glass in a cementitious composite. The absence of this deleterious reaction in the ECC mixtures evaluated has been attributed to the lower particle size of the GP which is less than 300 mm. Compared to limited previous works on the incorporation of GP into ECC mixtures, this study extensively experimentally evaluates the durability properties of ECC mixtures in terms of its shrinkage properties, permeability properties and resistance to alkali-silica reaction. It would be of great interest to carry out future works on the performance of ECC mixtures incorporating glass as both binder and aggregates.
CRediT authorship contribution statement Adeyemi Adesina: Conceptualization, Methodology, Investigation, Formal analysis, Visualization, Writing - original draft. Sreekanta Das: Conceptualization, Validation, Writing - review & editing, Supervision, Funding acquisition, Resources. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgement The authors acknowledge the Natural Sciences and Engineering Research Council of Canada for the financial support provided. References [1] V.C. Li, Interface tailoring for strain-hardening polyvinyl alcohol-engineered cementitious composite (PVA-ECC), ACI Mater. J. 99 (5) (2002) 463–472. [2] M.D. Lepech, V.C. Li, Water permeability of engineered cementitious composites, Cem. Concr. Compos. 31 (2009) 744–753. [3] N.M. Altwair, M.A.M. Johari, S.F.S. Hashim, Influence of treated palm oil fuel ash on compressive properties and chloride resistance of engineered cementitious composites, Mater. Struct. Constr. 47 (4) (2014) 667–682. [4] V.C. Li, Tailoring ECC for special attributes: a review, Int. J. Concr. Struct. Mater. 6 (3) (2012) 135–144. [5] V.C. Li, S. Wang, C. Wu, Tensile strain-hardening behavior or polyvinyl alcohol engineered cementitious composite (PVA-ECC), ACI Mater. J. 98 (6) (2001) 483–492. [6] E. Özbay, O. Karahan, M. Lachemi, K.M.A. Hossain, Atisß C. Duran, Investigation of properties of engineered cementitious composites incorporating high volumes of fly ash and metakaolin, ACI Mater. J. 109 (5) (2012) 565–572. [7] M. Batayneh, I. Marie, I. Asi, Use of selected waste materials in concrete mixes, Waste Manage. 27 (12) (2007) 1870–1876. [8] T.C. Ling, C.S. Poon, A comparative study on the feasible use of recycled beverage and CRT funnel glass as fine aggregate in cement mortar, J. Clean Prod. 29 (2012) 46–52. [9] M. Mageswari, D.B. Vidivelli, The use of sheet glass powder as fine aggregate replacement in concrete, Open Civ. Eng. J. 4 (2010) 65–71. [10] P. Penacho, J. De Brito, M. Rosário Veiga, Physico-mechanical and performance characterization of mortars incorporating fine glass waste aggregate, Cem. Concr. Compos. 50 (2014) 47–59. [11] N. Schwarz, N. Neithalath, Influence of a fine glass powder on cement hydration: comparison to fly ash and modeling the degree of hydration, Cem. Concr. Res. 45 (2008) 39–45. [12] M. Carsana, M. Frassoni, L. Bertolini, Comparison of ground waste glass with other supplementary cementitious materials, Cem. Concr. Compos. 45 (2014) 39–45. [13] Y. Jani, W. Hogland, Waste glass in the production of cement and concrete – A review, J. Environ. Chem. Eng. 2 (3) (2014) 1767–1775. [14] A. Khmiri, M. Chaabouni, B. Samet, Chemical behaviour of ground waste glass when used as partial cement replacement in mortars, Constr. Build. Mater. 44 (2013) 74–80. [15] A. Shayan, A. Xu, Value-added utilisation of waste glass in concrete, Cem. Concr. Res. 34 (1) (2004) 81–89. [16] H. Siad, M. Lachemi, M. Sahmaran, H.A. Mesbah, K.M.A. Hossain, Use of recycled glass powder to improve the performance properties of high volume fly ash-engineered cementitious composites, Constr. Build. Mater. 163 (2018) 53–62. [17] H. Siad, M. Lachemi, M. Sahmaran, K.M.A. Hossain, Mechanical, physical, and self-healing behaviors of engineered cementitious composites with glass powder, J. Mater. Civ. Eng. 29 (6) (2017) 1–12. [18] ASTM C109. Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [ 50-mm ] Cube Specimens) 1. Chem. Anal. 2010; (C109/C109M – 11b), 1–9. [19] E. Booya, K. Gorospe, H. Ghaednia, S. Das, Free and restrained plastic shrinkage of cementitious materials made of engineered kraft pulp fibres, Constr. Build. Mater. 212 (2019) 236–246. [20] ASTM C 642-2006, Standard test method for density, absorption, and voids in hardened concrete 4 (2006) 1–3. [21] ASTM C1757, ASTM Standard C1757 – Standard Test Method for Determination of One-Point, Bulk Water Sorption of Dried Concrete, ASTM Int., 2014, pp. 14–16. [22] ASTM C1585, Standard Test Method for Mesurement of Rate Absorption of Water by Hydraulic-Cement Concretes, Annu B ASTM Stand [Internet] 04 (147) (2004) 1–6.
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