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portland cement. In addition, it also utilizes waste or by-product material that makes it more environmentally friendly.
measured drying shrinkage strain from the tests.
greenhouse gasses from the production of portland cement as the primary binder in making concrete in the meantime.
or equation normally used for predicting drying shrinkage of ordinary portland cement (OPC) concrete.
content and low water cement ratio.
Drying shrinkage is the reduction in volume which is primarily caused by the loss of water during the drying process.
* H csd . The total shrinkage strain is given by Equation 1 and the endogenous shrinkage at any time t (in days) after concrete placement is given by Equation 2.Modern Applied Science December. 0 ) u 50 u 10 (3) in which f’c is in MPa.b*depends on the quality of the local aggregates and may be taken as 800 x 10-6 for Sydney and Brisbane. The drying shrinkage at time t (in days) after the commencement of drying may be taken as H csd k1k 4H csd .b (4) where İcsd. al. 0. 2009 drying of concrete also affect the magnitude and rate of development of drying shrinkage. The shrinkage strain of concrete which is usually considered to be the sum of drying.8 (6) k1 t 0. The higher water to cement ratio normally results in higher shrinkage due to interrelated effects. Those factors include the type and content of cement or binder.7 for an arid environment. th is given by Equation 8. and the factor k4 is taken equal to 0. if not controlled. Shrinkage also causes axial deformation and warping which could lead to significant deflection and the shrinkage induces tension and resulting cracks.008 f 'c ) u H csd . continues to increase with time at a decreasing rate (Gilbert. 06 f ' c  1 . Endogenous shrinkage is taken to be the sum of chemical and thermal shrinkage. paste strength and stiffness decrease and as the water content increases. Shrinkage is a concern in concrete structures since it is probably the most common cause of cracking. H cs H cse  H csd (1) H cse H cse * (1. water content and water to cement ratio. relative humidity and the size and shape of the member. D 1t 0. 2A (8) th ue 15 . The aggregates plays a significant role in affecting the shrinkage of concrete (de Larrard et. And as for creep. One of them is as proposed by Gilbert (2002) that will be used in this study as a comparison to the experimental results. 1994).b is given by Equation 5..8  0. durability and even shear strength failure (Gilbert. can lead to serviceability. 1994.0  0.15t h where D1 0. 2002). The method proposed by Gilbert divides the total shrinkage strain (Hcs) into endogenous shrinkage (Hcse) and drying shrinkage (Hcsd).b (1.. where A is the cross-sectional area of the member and ue is that part of the perimeter of the member cross. but the duration of shrinkage is longer for large members since more time is needed for shrinkage effects to reach the interior regions (de Larrard et. This is related to the restraining effect of the aggregate on shrinkage.5 for a tropical or near-coastal environment.b (5) The factor k1 in Equation 4 is given by Equation 6.8  1. shrinkage potential increases because it also reduces the volume of restraining aggregates. The rate and magnitude of shrinkage decrease with an increase in the volume of concrete member.65 for an interior environment. 1988. maximum size and its proportion in the concrete..2e 0. Neville. 0.005t h (7) and the hypothetical thickness. 900 x 10-6 for Melbourne and 1000 x 10-6 elsewhere.0  e 0. Rusch et. shrinkage is also assumed to approach a final value as time approaches infinity. As water to cement ratio increases. al. The higher aggregate content results in smaller shrinkage and also concrete with aggregates of higher modulus or rougher surfaces is more resistance to the shrinkage process. In Equation 5. The relative humidity affects the magnitude of shrinkage as the rate of shrinkage is lower at higher values of relative humidity. 2000). type of aggregate. There are some formulas or equations that have been developed to estimate the shrinkage of concrete. İcsd.1t ) (2) * Where Hcse is the final endogenous shrinkage and may be taken as * 6 H cse ( 0 . al.6 for a temperate inland environment and 0.section which is exposed to the atmosphere. chemical and thermal shrinkage components. 1983).
comprising 20 mm.4%. and then once in four weeks until one year.9% by mass solution). Two types of curing were applied. The specimens were cured at 60oC for 24 hours. van Jaarsveld. 14 mm and 7 mm coarse aggregates and fine aggregate in saturated surface dry conditions. 4. Experimental Work Geopolymer concrete in this study utilized the low calcium (class F) fly ash from Collie Power Station. 2007). 2006.Vol.e. In geopolymer concrete. et. (2004) who studied the development of this concrete including the effects of various parameters. the specimens were left to air-dry in the laboratory until testing. Previous studies also indicates that fly ash-based geopolymer concrete possesses good long-term properties and durability (Wallah. In this experimental work. This geopolymer gel binds the loose aggregates and other unreacted materials in the mixture to form the geopolymer concrete. once a week until the fourth week. 5. Aggregates. Wallah and Rangan. 2DS. The measurements then continued every day in the first week. Two types of heat curing which is dry curing and steam curing. Unlike the cement-based concretes that utilise the formation of calcium-silica hydrates (CSHs) for matrix formation and strength.13 (1992) was used as the basis to determine the drying shrinkage through an experimental or laboratory testing. et. The first two comes from one mixture proportion designed for higher strength while the other two comes from one mixture proportion with lower strength. The relative humidity of the room varied between 40% and 60%.. al. 1994). in fly ash-based geopolymer concrete. Fly Ash-Based Geopolymer Concrete Fly ash-based geopolymer concrete is geopolymer concrete utilizes fly ash as its source material. were applied with one type for one test series in each mixture. instead of cement paste. During the drying shrinkage tests. Three specimens were prepared for each type of test. 3DS and 4DS. For dry curing.. SiO2=29. 2006). Previous research has been reported on the studies of fly ash-based geopolymer concrete as in Hardjito et. the specimens were cured in an oven and for steam curing the specimens were cured in the steam curing chamber. 12 Modern Applied Science 3. et al. The manufacture of geopolymer concrete is carried out using the usual concrete technology methods. No. 2004.5% by mass of the fly ash was added to the mixture. The use of geopolymer technology in making concrete has environmental benefit as it could reduce the CO2 emission to the atmosphere up to 80% compared to OPC concrete (Davidovits. and water=55. This study focused on the drying shrinkage of fly ash-based geopolymer concrete. The coarse aggregates were crushed granite-type aggregates and the fine aggregate was fine sand. The geopolymer paste binds the loose coarse aggregates. On the third day after casting. fine aggregates and other un-reacted materials together to form the fly ash-based geopolymer concrete. considered as Day 1 for the drying shrinkage measurements. the specimens were demoulded and the first measurement was taken. 2002). where the procedure as in Australian standard. four 100x200 mm cylindrical specimens were also prepared for compressive strength test. the specimens were kept in a laboratory room where the temperature was maintained at approximately at 23oC. As in the Portland cement concrete. once in two weeks until the twelfth week. Test specimens for drying shrinkage test were 75x75x285 mm prisms with the gauge studs as shown in Figure 1. After curing. 1991. Chang. A high range water-reducing admixture with a dosage of 1. Four series of concrete specimens (Table 1) were used for drying shrinkage test designated with 1DS. In addition. Horizontal length comparator (Figure 2) was used for length measurements. Western Australia as the source material. AS 1012. were used. The alkaline activator was a combination of analytical grade sodium hydroxide (NaOH) in flake form with 98% purity dissolved in water and sodium silicate (Na2O= 14. The silicon and the aluminium in the fly ash are activated by a combination of sodium hydroxide and sodium silicate solutions to form the geopolymer paste that binds the aggregates and other un-reacted materials. The source material for making geopolymer concrete should be rich in silica and alumina. fly ash-based geopolymer concrete is a potential material for structural application (Sumajouw and Rangan. the aggregates occupy the largest volume. the silica and the alumina present in the source materials are first induced by alkaline activators to form a gel.1 Shrinkage Test Results Table 2 presents the resulted 7th day compressive strength of each test category. the compressive strength is 65 MPa and 57 MPa for 1DS and 2DS respectively.7%. The next measurement was on the fourth day of casting. al. about 75-80 % by mass. 16 . i. fly ash is used as the source material to make geopolymer paste as the binder. while for mixture-2. The shrinkage strain measurements started on the third day after casting the concrete. Results and Discussions 5. for each type of test. to produce concrete. al. geopolymers involve the chemical reaction of alumino-silicate oxides with alkali polysilicates yielding polymeric Si – O – Al bonds (Davidovits. For concrete from mixture-1. 3. those values are 50 MPa and 41 MPa for 3DS and 4DS respectively. Moreover.. dry curing or steam curing.
2 July 1999). (1999. Australia. & Rangan. The test measurement at one year for all test series of specimens with different compressive strength. 6(2). so that they can act as ‘micro-aggregates’ in the system and this could ‘increase’ the aggregate content in concrete. 7. does not have significant difference. there were some minor differences in the measured values of drying shrinkage strains between dry and steam cured specimens.65 as the test specimens were exposed to an interior environment and the value of f’c was taken as the 7th day compressive strength of the test specimens as given in Table 2. the insides of the atoms are not destroyed and remain stable. In other words. This could be attributed to the moisture movement from the environment to the concrete or vice versa which causes reversible shrinkage or swelling of the concrete.. In these calculations. Global Warming Impact on the Cement and Aggregates Industries. Therefore. Paper presented at the The 23rd Biennial Conference of the Concrete Institute of Australia. 30 June . 2009 Figures 3 and Figure 4 show the plots of drying shrinkage strain versus age in days for the heat-cured test specimens. Hardjito & Rangan. Davidovits.. In this study. N. (2007). The proportion of aggregates in the mixtures of fly ash-based geopolymer concrete used in this work is approximately similar to that used in OPC concrete. France. Because the remaining water contained in the micro-pores of the hardened concrete is small.2 Comparison of Test Results and Prediction The drying shrinkage of heat-cured fly ash-based geopolymer concrete is generally very low compared to that of ordinary portland cement concrete. V. Lloyd. H. 2005). Also. Terminology. the presence of the ‘micro-aggregates’ due to the ‘block-polymerisation’ gives the effect of increasing the aggregate content in the concrete. World Resource Review. about five to seven times of the measured drying shrinkage strain. the factor k4 was taken as equal to 0. The measured shrinkage strains are compared with the predictions by Gilbert method in Figure 5 to Figure 8. Saint-Quentin. which is also included in the Australian Standard for Concrete Structures AS3600 as described in Section 2. For all test specimens. Conclusion Heat-cured fly-ash based geopolymer concrete undergoes very low drying shrinkage. Although each type of mixture and curing type results in different compressive strength. Paper presented at the Geopolymere '99 International Conference. 1999. The test data plotted in Figures 3 and 4 show that the drying shrinkage strains fluctuated slightly over the period of measurement. 17 . Davidovits (Personal communication) suggested that the smaller drying shrinkage strain of heat-cured fly ash-based geopolymer concrete may be explained by the ‘block-polymerisation’ concept. J. the drying shrinkage strain does not have significant difference among those four series of tests. Sarker. According to this concept.Modern Applied Science December. It can be seen from these Figures that heat-cured fly ash-based geopolymer concrete undergoes very low drying shrinkage. Adelaide. However. these variations are considered to be insignificant in the context of the very low drying shrinkage experienced by the heat-cured geopolymer concrete specimens. the silicon and aluminium atoms in the fly ash are not entirely dissolved by the alkaline liquid.. from both mixtures and curing types and different compressive strength. It can be seen from Figures 5 to Figure 8 that the measured drying shrinkage strains of heat-cured fly ash-based geopolymer concrete specimens are significantly smaller than the predicted values. References Chang. aggregate content will influence the magnitude of shrinkage as the shrinkage of concrete will decrease with the increase in the quantity of aggregates. The ‘polymerisation’ that takes place only on the surface of the atoms is sufficient to form the ‘blocks’ necessary to produce the geopolymer binder. (1994). the induced drying shrinkage is also very low. J. 263-278. B. 5.. the measured drying shrinkage strains are compared with the values predicted by a method proposed by Gilbert (2002). P. The drying shrinkage strains fluctuated slightly over the period of measurement and the value at one year measurement is only around 100 microstrain. Shear behaviour of reinforced fly ash-based geopolymer concrete beams. This can also be seen if the test results are compared with the values predicted by using one of the available prediction formula for OPC concrete. However. most of the water released during the chemical reaction may evaporate during the curing process (Davidovits. which were produced from different mixtures and curing types. E. In heat-cured fly ash-based geopolymer concrete. Chemistry of Geopolymeric Systems. Davidovits. the final value of drying shrinkage strain after a one-year period was only around 100 microstrain. The values of drying shrinkage strain predicted using Gilbert Method is much higher. the presence of the ‘micro-aggregates’ increases the restraining effect of the aggregates on drying shrinkage. As for OPC concrete.
1633-1656. High Performance Concretes and Smart Materials. & Rangan. Sumajouw. J. Shrinkage creep and thermal properties. J. S. Geopolymer Concrete: A Key for Better Long-Term Performance and Durability. F.. M. On the Development of Fly Ash-Based Geopolymer Concrete. Table 1. J. K.. ACI Materials Journal. Hardjito. Creep and shrinkage models for high strength concrete . S. Sumajouw. G. In S. D. Chemical Engineering Journal. Hardjito. D. J. Perth.. E. Rusch. Journal of Thermal Analysis. Neville. (1991). 95-106. Gilbert.. England: Pearson Education. Jungwirth.and kaolinite-based geopolymers. D. Perth. B. No.1992. L. (2006). Curtin University of Technology. D. B. P.). The effect of composition and temperature on the properties of fly ash. (2006). J. 12 Modern Applied Science Davidovits. & Rangan. Australian Journal of Structural Engineering. Low-Calcium Fly Ash-Based Geopolymer Concrete: Long-Term Properties. (1983). D. Creep and Shrinkage. & Roy. van Jaarsveld. Development and Properties of Low-Calcium Fly Ash-Based Geopolymer Concrete. 101(6). (2004). & Rangan. H. Properties of Concrete (Fourth and Final ed.. Methods of testing concrete . Ahmad (Eds. J. Test Parameters for Drying Shrinkage Test Test Designation Mixture Curing type 1DS Mixture-1 Dry 2DS Mixture-1 Steam 3DS Mixture-2 Dry 4DS Mixture-2 Steam Table 2. London: Edward Arnold. Wallah. V. (1994). 37. (2005). Time Effects in Concrete Structures. S. (2000). G.. I. Their Effect on the Behaviour of Concrete Structures. Australia: Faculty of Engineering. V. Essex. A. C. AS 1012. Australia: Faculty of Engineering. Compressive Strength of Heat-Cured Fly Ash-based Geopolymer Concrete Shrinkage Specimens 7th Day compressive Test Designation Type of mixture Curing type strength (MPa) 1DS Mixture-1 dry 65 2DS Mixture-1 steam 57 3DS Mixture-2 dry 50 4DS Mixture-2 steam 41 18 . R. H. 4(2). R. R. (2002). & Rangan. B. Shah & S. 63-73. Standards-Australia. Wallah.. J. (1988). New York: Springer-Verlag.Determination of the drying shrinkage of concrete for samples prepared in the field or in the laboratory. 467-472.13 . M. D. S.proposal for inclusion in AS3600. Geopolymers: Inorganic Polymeric New Materials. V. India. van Deventer.. D.. (2002). Australia: Faculty of Engineering. de Larrard. E.. V. H. V. Acker. (1992). Wallah. B. B. Curtin University of Technology..Vol. Amsterdam: Elsevier.. Paper presented at the ICFRC International Conference on Fibre Composites.). Chennai. & Lukey. S.. P. Gilbert. High Performance Concretes and Applications (pp. 65-114).. 3. Longman Group. Hardjito. Sumajouw. 89(1-3). & hilsdorf.. I. M. (2004). & Rangan. M. Curtin University of Technology. Perth. Low-Calcium Fly Ash-Based Geopolymer Concrete: Reinforced Beams and Columns. E.
Modern Applied Science December. Horizontal Length Comparator with a Drying Shrinkage Test Specimen 600 500 Drying shrinkage strain 1DS (Dry curing) 2DS (Steam curing) (microstrain) 400 300 200 100 0 0 100 200 300 400 Age (days) Figure 3. Specimens for Drying Shrinkage Test Figure 2. Drying Shrinkage of Heat-Cured Mixture-1 Specimens 19 . 2009 Figure 1.
12 Modern Applied Science 600 500 Drying shrinkage strain 3DS (Dry curing) 4DS (Steam curing) (microstrain) 400 300 200 100 0 0 50 100 150 200 250 300 350 400 Age (days) Figure 4.Vol. 3. No. drying shrinkage 200 100 0 0 50 100 150 200 250 300 350 400 Age (days) Figure 6. Comparison of Test and Predicted Shrinkage Strains for 2DS 20 . drying shrinkage 300 prediction. drying shrinkage 300 prediction. Comparison of Test and Predicted Shrinkage Strains for 1DS 700 600 Strain (microstrain) 500 400 test. Drying Shrinkage of Heat-Cured Mixture-2 Specimens 600 500 Strain (microstrain) 400 test. drying shrinkage 200 100 0 0 50 100 150 200 250 300 350 400 Age (days) Figure 5.
Comparison of Test and Predicted Shrinkage Strains for 3DS 800 700 Strain (microstrain) 600 500 test. 2009 700 600 Strain (microstrain) 500 400 test.Modern Applied Science December. drying shrinkage 300 prediction. drying shrinkage 400 prediction. drying shrinkage 300 200 100 0 0 50 100 150 200 250 300 350 400 Age (days) Figure 8. drying shrinkage 200 100 0 0 50 100 150 200 250 300 350 400 Age (days) Figure 7. Comparison of Test and Predicted Shrinkage Strains for 4DS 21 .
PVN Acharya's work in France with Societe Organico, Birla; Synthetic Fibers from Castor Oil and ground nut oils.

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