Research Journal of Recent Sciences _________________________________________________ ISSN 2277-2502 Vol. 2(11), 20-28, November (2013) Res.J.Recent Sci. International Science Congress Association 20 Statistical Correlation to Predict the Compressive Strength of Binary and Ternary Blended ConcretesHariharan A.R., Santhi A.S.and Mohan Ganesh G. Structural and Geotechnical Engineering Division, SMBS, VIT University, Vellore-632014, INDIAAvailable online at: www.isca.in , www.isca.me Received 4th May 2013, revised 13th June 2013, accepted 15th July 2013Abstract This research paper presents the effects of using supplementary cementitious materials in binary and ternary blends of concrete incorporating fly ash and silica fume. A total of 12 concrete mixtures were designed having a total binder content of 400 kg/m and water binder ratio of 0.4. Portland cement was replaced by fly ash at levels of 30%, 40% and 50%, silica fume at levels of 6% and 10% by weight. The compressive strength test were conducted on test specimens cured under different types of curing systems like accelerated curing, warm water curing along with normal curing were done and the results were compared. Based on the experimental results, polynomial regression models and coefficients were developed between standard compressive strength and early strength attained by accelerated curing and warm water curing at 28-90 days. Keywords: Compressive strength, curing type, fly ash, silica fume, industrial waste. IntroductionIn recent years cement and concrete has been in high demand due to infrastructure development. Cement industry is one of the major sources of environment pollution. For economic and environmental reasons cement has been replaced by some materials having pozzolanic and cementitious properties. These materials are industrial waste which comes as a by-product. Some of the most common industrial wastes are fly ash (FA), silica fume (SF), ground granulated blast furnace slag, metakaolin and rice husk ash. These industrial materials are also referred to as supplementary cementitious materials (SCMs). Fly ash is widely used in blended cements, and is a by-product of coal-fired electric power plants. Two general classes of FA can be defined: low-calcium fly ash (LCFA: ASTM Class F) produced by burning anthracite or bituminous coal; and high-calcium fly ash (HCFA: ASTM Class C) produced by burning lignite or sub-bituminous coal. The use of FA in concrete is not only economical but also modifies the properties of concrete in both fresh and hardened state with improved workability. In addition, the storage and disposal problem of fly ash is also solved by the use of fly ash in concrete . Despite the benefits of fly ash, practical problems remain in field application. At early stages of aging, the strength of concrete containing a high volume of fly ash as a partial cement replacement is much lower than that of control concrete, due to the slow pozzolanic reactivity of fly ash. Silica fume appears to be a potential solution to this problem due to its highly reactive nature. Silica fume is a pozzolanic material which is a by-product of the silicon melting process. It is used to improve concrete in two ways the basic pozzolonic reaction and also acts as micro filler. The addition of SF also affects the workability of concrete which can be compensated by addition of chemical admixtures. Therefore, utilization of SF together with FA provides an interesting alternative for cement3,6. The criterion for the quality of concrete is based on the 28-days compressive strength of cube specimen cast, cured and tested under controlled condition. Currently, however the increasing speed of construction calls for potential strength of concrete to be determined at the earliest possible time after the concrete has been placed . Therefore methods for early determination of concrete strength are accelerated curing and warm water curing. Hence, this paper presents the experimental results of compressive strength of binary-ternary combinations of FA and SF under different curing condition. Polynomial regression analyses were performed to establish a relationship between standard compressive strength and accelerated/warm water compressive strength of concretes made with PC and different amounts of FA and SF. Material and Methods Experimental Study: The materials used in this study were tested for their chemical and physical properties as shown below. Cement: Portland cement (PC) conforming to the requirements of BIS: 12269-1987 (53 grade) was used, for which the physical property tests of the cement were carried out in the laboratory and were found to have a specific gravity of 3.15 and the initial and final setting time were found to be 150 minutes and 265 minutes respectively. Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 21 Aggregates: The fine and coarse aggregates were local natural river sand and crushed gravel respectively. The coarse aggregate passing through 20 mm and retained on 4.75 mm was used for all mixtures. The specific gravity of coarse aggregate was 2.65. The specific gravity and fineness modulus of fine aggregates were 2.56 and 2.65. Chemical Admixture: A new generation Polycarboxylic ether (PCE) based superplasticizer (SP) was used. The super -plasticizer is available as a medium brown colored aqueous solution. This chemical admixture was meeting the standards of ASTM specification C494/C494M-11. The specific gravity and pH value of the superplasticizer is 1.056 and 6.5 respectively. Fly ash: High-calcium fly ash with a specific gravity of 2.46 from a source in Neyveli, India (lignite base fly ash) was used in this investigation. The chemical compositions of the fly ash are shown in table 1. Silica fume: Uncompacted silica fume from Elkem, India with specific gravity of 2.02, bulk density of 602 (kg/m) and specific surface of 19 (m/g) was used in this study. The chemical analyses of the silica fume are presented in table 1. Table-1 Chemical properties of Class C fly ash and silica fume Characteristics From Test Fly ash- Class C Silica Fume Silica (as Si0 2 ), Min 57.65 85.72 Calcium Oxide (Lime Content) as CaO 11.64 - Alumina (as Al 2 0 3 ) 15.29 0.06 Iron oxide (as Fe 2 O 3 ) 6.10 0.45 Magnesia (as MgO), Max 0.37 - Sulphuric Anhydride (as S0 3 ), Max 1.82 - Total Loss on ignition, Max 2.86 1.96 Total Chlorides (as Cl) 0.02 - Sodium Oxide (as Na 2 O) 0.44 - Potassium Oxide (as K 2 O) 0.04 - Total alkalis (as NaO) Silicon dioxide (SiO) + Aluminum oxide (Al) + Iron Oxide (Fe) in % by mass, Min0.47 79.04 - - Mixture Proportions: A total of 12 concrete mixtures were designed having a total binder content of 400 kg/m with a constant water/binder ratio of 0.4. Also, SP was added to all mixtures to increase workability of concrete. The concrete mixtures were divided as below: i. Control mixture with only PC as a binder. ii. Five binary mixtures with 30%, 40% and 50% FA replacement, 6% and 10% SF replacement respectively by weight of the PC for 400 kg/m, iii. Six ternary concrete mixtures (PC+FA+SF) with replacement levels of FA and SF as in binary mixtures of PC+FA and PC+SF. The mixture ID are furnished in table 2 and the mix proportions, SP content, aggregate content and SCMs content by weight used in this experimental study are summarized in table 3 for 400 kg/m. Casting: The mixing sequence and duration are very important to produce good quality concrete. For all the twelve mixture selected in this study, twenty one cubes of size 100 mm x 100 mm x 100 mm were cast per mix. Batching, mixing and placing of concrete in its moulds were done as per the ASTM C192/C192M-07 10. Table-2 Mixture ID of samples of Concrete Specimens Mix ID of 400 kg/mCement (%) Fly ash (%) Silica fume (%) T100 100 - - T906 94 - 6 T901 90 - 10 T730 70 30 - T640 60 40 - T550 50 50 - T636 64 30 6 T546 54 40 6 T456 44 50 6 T631 60 30 10 T541 50 40 10 T451 40 50 10 Curing: The chemical process that ensures the hydration of cement in a newly placed concrete is curing. In this work it was decided to study the effect of curing, by adopting three types of curing methods as per ASTM C684-99 11 standards. These curing conditions are: i. standard moist curing: after casting, the molded specimens were left in the casting room for 24 h. It was then demoulded and immersed in a curing tank full of water. The specimens were removed from the tank at the time of testing; ii. Warm water method: immediately after casting, the concrete moulds were sealed with cover plates and immersed in water maintaining 55C. The specimen remained in warm water for 24 h. After which the concrete cubes were demoulded, and allowed to cool down at room temperature, and then tested; iii. Accelerated curing method: after 24 h from casting the molds were immersed in accelerated curing tank maintaining of 98C for 3.5 h. After which the specimens were removed from the tank, demoulded and allowed to cool down and tested. Testing of Specimens: The concrete cubes were tested in compression at 1, 3, 7, 28 and 90 days. All specimens for compression testing were done in accordance with Indian Standards BIS: 516-1959 12 using digital compression testing machine with a capacity of 3000 kN at a loading rate of 2.5 kN/sec. Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 22 Experimental Test Result: The compressive strength test results obtained from the experimental investigation involving various parameters are shown in table 4 and 5 for all the mixtures. Further in figure 1 and 2 graphs are plotted between compressive strength of binary- ternary mixtures with respect to the three curing methods and in figure 3 and figure 4 the compressive strength with respect to age (up to 90 days) were plotted. Table-3 Mixture Proportion of Concrete Specimens Mixture ID W/B Cement (kg/m) Fly Ash (kg/m) Silica Fume (kg/m) Fine Aggregate (kg/m) Coarse Aggregate (kg/m) Super plasticizer (kg/m) T100 0.4 400 - - 1104 736 0.117 T906 0.4 376 - 24 1104 736 0.147 T901 0.4 360 - 40 1104 736 0.206 T730 0.4 280 120 - 1104 736 0.235 T640 0.4 240 160 - 1104 736 0.264 T550 0.4 200 200 - 1104 736 0.323 T636 0.4 256 120 24 1104 736 0.411 T546 0.4 216 160 24 1104 736 0.382 T456 0.4 176 200 24 1104 736 0.352 T631 0.4 240 120 40 1104 736 0.323 T541 0.4 200 160 40 1104 736 0.440 T451 0.4 160 200 40 1104 736 0.499 Table-4 Compressive strength of binary and ternary concrete mixtures subjected to Accelerated, Warm water and One day normal curing methods Curing Type Compressive Strength N/mm 2 Control OPC + SF OPC + FA OPC + FA +SF T100 T906 T901 T730 T640 T550 T636 T546 T456 T631 T541 T451 Accelerating 35 34.25 45.53 27.57 25.13 16.87 25.35 35.85 30.25 31.3 26.15 27.35 Warm Water 29.75 31.9 44.65 24.55 19.83 15.15 19.75 29.85 23.45 31.35 16.75 21.1 1 day strength 21.03 21.5 22.67 14 12.97 12.35 18.4 17.4 12.48 19.3 16.53 10.55 Table-5 Compressive strength of binary and ternary concrete mixtures subjected to normal curing up to 90 days Curing Age in Days Compressive Strength N/mm Control OPC + SF OPC + FA OPC + FA +SF T100 T906 T901 T730 T640 T550 T636 T546 T456 T631 T541 T451 1 21.03 21.5 22.67 14 12.97 12.35 18.4 17.4 12.48 19.3 16.53 10.55 3 33 35.45 37.65 26.23 22.35 20.25 33.4 26.4 20.45 33.55 25.7 18.47 7 42.43 43.43 43.7 32.55 31.5 25.7 44.95 41.07 24.85 42.6 36.4 26.3 28 50.5 56.83 53.27 44.9 41.73 38.8 51.5 45 39.15 50.95 50.6 38.27 90 60.6 64.03 61.2 60.9 56.9 50.5 61.1 59 51.1 60.97 57.9 49.05 Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 23 Figure-1 Compressive strength of binary concrete mixtures incorporating fly ash or silica fume under different methods of curing (PC+SF)/ (PC+FA)Figure-2 Compressive strength of ternary concrete mixtures incorporating fly ash and silica fume under different methods of curing (PC+FA+SF) Figure-3 Binary effects of fly ash and silica fume on the compressive strength of concrete with reference to control concrete under normal curing One day Normal CuringAcceleratedWarm WaterCompressive Strength (N/mm   \n     \n  One day Normal CuringAcceleratedWarm WaterCompressive Strength (N/mm  \n\n \n \n \n   \n   Compressive Strength (N/mmAge in Days   \n     \n  Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 24 Regression Analysis: From the test results, graphs were plotted between standard compressive strength versus early age strength of binary and ternary concrete mixtures. In figures 5 the regression analyses were carried out for accelerating curing versus standard curing and warm water curing versus standard curing respectively at 28 days. The relation between the accelerated strength and standard strength upon normal curing was obtained as a second order polynomial equation as seen in equation (1). Similarly the relation between the warm water strength and standard strength was given equation (2). Based on equations proposed compressive strength of binary and ternary concrete cubes at 28 and 90 days can be predicted. cu = fc.acc + fc.acc+ (1)cu = fc.ww + fc.ww+ (2)Where, fcu – compressive strength of concrete at 28 or 90 days, c.acc – Accelerated curing compressive strength at early age, fc.ww– Warm water curing compressive strength at early age and ,andare the regression constants. This relationship is in line with the findings of the other researchers who have adopted regression analysis to predict the strength of normal concrete and concrete incorporating FA7,13. The constants , and of the above equation depends on the age and type of the SCM's used in the concrete. The regression coefficients for binary-ternary combinations of FA and SF are given in table 6 and 7 for 28 and 90 days respectively. The early strength of concrete under different curing condition obtained from experiments was substituted in equations 1 and 2, and the compressive strength of concrete at 28 and 90 days were predicted. The compressive strength obtained by the predicted values and experimental results under accelerated curing and warm water curing along with the percentage of errors are tabulated in table 8 and 9. From these tables, it is observed that, the binary PC+SF mixtures have a maximum error for mixtures incorporating higher percentage of SF (10%) on both 28 and 90 days. On the other hand, the binary PC+FA mixtures showed a maximum error for mixture incorporating lesser percentage of FA (30%) on all days under both curing conditions. The percentage of error decreases with increase in FA content. For analysis, the ternary mixtures are split into two categories; (1) (PC+SF+FA) incorporating 6% SF and (2) (PC+SF+FA) incorporating 10% SF. The ternary mixtures with 6% SF showed a maximum error of 0.056% for T546 at 28 under accelerated curing. Also the mixture with lesser percentage of FA, T636 showed a least error on all days. The ternary mixtures with 10% SF showed maximum error for T451 (0.21%) at 28 days under accelerated curing. In general all the mixtures showed lesser percentage or zero error at 90 days compared to 28 days, which means the prediction equations, predicts the actual result at later ages. The proposed relationship is independent of the amount of FA and SF present in them. The average percentage of error values are 0.073 and 0.047 for accelerated curing and warm water curing respectively at 28 days as shown in table 8. Similarly, the average error for accelerated curing and warm water curing at 90 days are 0.028 and 0.037 respectively as shown in table 9. Therefore the average error is less than 1% which is negligible. Figure-4 Ternary effects of fly ash and silica fume on the compressive strength of concrete with reference to control concrete under normal curing \n      Compressive Strength (N/mmAge in Days  \n\n \n \n \n   Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 25 Table-6 Regression coefficients for accelerated curing and warm water curing of binary-ternary concrete mixtures at 28 days Description Mixture ID 28 Days Strength Accelerated Curing Warm Water Curing    R 2    R 2 Control T100 0.7715 -61.87 1270.8 1 -0.216 16.281 -242.4 1 Binary Mix PC+SF T906 0.7715 -61.87 1270.8 1 -0.216 16.281 -242.4 1 T901 Binary Mix PC+FA T730 0.0883 -3.352 70.236 1 0.0048 0.4566 30.771 1 T640 T550 Ternary Mix PC+SF+FA With 6% SF T636 0.3395 -21.39 375.76 1 0.421 -21.524 312.39 1 T546 T456 Ternary Mix PC+SF+FA With 10% SF T631 2.6185 -150.3 2192 1 0.2789 -13.39 196.64 1 T541 T451 Figure-5 Regression plot for binary and ternary concrete samples subjected to accelerated and warm water curing methods versus 28 days strength of normal curing \n\n Compressive strength in N/mmWarm water compressive strength in N/mm  PC+SF-Binary Mixture PC+FA -Binary Mixture Ternary Mixture with 6 % SF Ternary Mixture With 10 % SF \nCompressive strength in N/mmAccelerated compressive strength in N/mm  \r \r  \n! " ! Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 26 Table-7 Regression coefficients for accelerated curing and warm water curing of binary-ternary concrete mixtures at 90 days Description Mixture ID 90 Days Strength Accelerated Curing Warm Water Curing    R2    R2 Control T100 0.4105 -33 712.74 1 -0.122 9.1146 -102.6 1 Binary Mix PC+SF T906 0.4105 -33 712.74 1 -0.122 9.1146 -102.6 1 T901 Binary Mix PC+FA T730 0.0923 -3.10 76.553 1 -0.048 3.0663 15.19 1 T640 T550 Ternary Mix PC+SF+FA With 6% SF T636 0.3287 -20.31 364.91 1 0.389 -19.54 295.01 1 T546 T456 Ternary Mix PC+SF+FA With 10% SF T631 -0.091 5.8643 -32.74 1 -0.005 0.4641 51.607 1 T541 T451 Table-8 Predicted compressive strength of binary-ternary concrete mixtures at 28 days and their corresponding error values Mixture Id Curing age in days Accelerated Curing Vs. Normal Curing Warm water Curing Vs. Normal Curing c.acc fcu fcupre% Error c.ww fcu fcupre% Error T100 28 35 50.5 50.43 0.123 29.75 50.5 50.52 0.041 T906 28 34.25 56.83 56.77 0.105 31.9 56.83 56.85 0.043 T901 28 45.53 53.27 53.16 0.2 44.65 53.27 53.32 0.105 T730 28 27.57 44.9 44.92 0.055 24.55 44.9 44.87 0.059 T640 28 25.13 41.73 41.75 0.049 19.83 41.73 41.71 0.041 T550 28 16.87 38.8 38.8 0.023 15.15 38.8 38.79 0.025 T636 28 25.35 51.5 51.49 0.017 19.75 51.5 51.5 0.014 T546 28 35.85 45 44.97 0.056 29.85 45 45.01 0.042 T456 28 30.25 39.15 39.13 0.04 23.45 39.15 39.17 0.028 T631 28 31.3 50.95 51.05 0.196 31.35 50.95 50.97 0.044 T541 28 26.15 50.6 50.67 0.148 16.75 50.6 50.6 0.012 T451 28 27.35 38.27 38.35 0.21 21.1 38.27 38.28 0.026 Average Error 0.101 Average Error 0.04 Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 27 Table-9 Predicted compressive strength of binary-ternary concrete mixtures at 90 days and their corresponding error values Mixture Id Curing age in days Accelerated Curing Vs. Normal Curing Warm water Curing Vs. Normal Curing c.acc fcu fcupre% Error c.ww fcu fcupre% Error T100 90 35 60.6 60.6 0.004 29.75 60.6 60.57 0.046 T906 90 34.25 64.03 64.03 0.003 31.9 64.03 63.99 0.051 T901 90 45.53 61.2 61.2 0.014 44.65 61.2 61.13 0.106 T730 90 27.57 61.2 61.2 0.012 24.55 61.2 61.17 0.035 T640 90 25.13 56.9 56.9 0.011 19.83 56.9 56.88 0.024 T550 90 16.87 50.5 50.5 0.004 15.15 50.5 50.49 0.016 T636 90 25.35 61.1 61.14 0.006 19.75 61.1 61.1 0.003 T546 90 35.85 59 58.99 0.003 29.85 59 59 0.003 T456 90 30.25 51.1 51.1 0.003 23.45 51.1 51.1 0.004 T631 90 31.3 60.97 60.97 0 31.35 60.97 60.94 0.036 T541 90 26.15 57.9 57.89 0 16.75 57.9 57.89 0.01 T451 90 27.35 59.05 59.04 0.001 21.1 59.05 59.03 0.017 Average Error 0.005 Average Error 0.029 Results and Discussion The experimental results and the statistical results of compressive strength with different replacement levels of FA and SF under different curing conditions are discussed in the following paragraphs; i. The addition of 6% and 10% SF as a binary mixture showed a higher compressive strength of 7-10% in average than control concrete on all days under all three curing conditions, irrespective of the percentage of SF present in them. ii. The dosage of SF has a significant effect on the compressive strength of concrete under normal curing. The concrete mixture with 10% SF (T901) showed a 5% higher strength than 6% SF (T906) mixture at 1 day and 3 days. At 7 days the compressive strength of PC+SF mixtures was almost equal irrespective of percentage of SF. The increase in the curing period increases the strength of T906 concrete specimens by 6% compared to T901 at 28 and 90 days. These observations are consistent with the results of Ali Behnood, Hasan Ziari14. iii. The 1, 3, 7 and 28 days compressive strength of (PC+FA) binary mixture incorporating 30%, 40% and 50% FA was lower by 17-42% in average than control concrete under normal curing with the same binder content. However as the curing period is extended up to 90 days the concrete incorporating 30% FA (T730) mixture had 2% higher compressive strength than control concrete. This is because the pozzolanic reaction is slow and the formation of calcium hydroxide requires time. iv. It is evident from the experimental results that the compressive strength decreases when the percentage of fly ash increases. Too high FA content (40% and 50%) as a binary mixture reduces the strength at all days under normal curing. The accelerated and warm water curing methods accelerates the strength of high volume fly ash concrete compared to normal curing at the early age. v. The test results of the ternary mixtures T636 and T631 (30% FA and 6-10% SF) showed 2-5% higher compressive strength than the control concrete on all days under normal curing. The other ternary mixtures made with 40%-50% FA with 6%-10% SF showed a more or less equal compressive strength of the control concrete at later ages. But all the ternary mixture except T456 and T451 showed a higher strength than the binary PC+FA mixtures on all initial days. vi. Equation (1) and (2) are proposed for two relationships between the early age strength and long term strength, based on the curing condition at the early age. The percentage error for the proposed equations is negligible (less than 1%). Hence these equations are useful to predict the compressive strength of concretes incorporating binary blends of fly ash and silica fume and also for the ternary mixtures incorporating both of these mineral admixtures at 28 and 90 days. Conclution From the experimental study and statistical model, the following conclusions can be drawn; The utilization of fly ash along with silica fume was found to increase the compressive strength of concrete mixes. The replacement level of cement by these supplementary cementitious materials was 30% FA and 6 to 10% SF. Apart from the increase in strength, it also allows to use two industrial by-products which would offer ecological benefits by using the available mineral admixtures, helps in cutting down the use of cement, energy saver and reduce the cost of concrete construction in the countries with abundant supply of fly ash. The proposed model would possibly provide 332equality between the quality of concrete, time and cost. By predicting the 28 and 90 days strength of concrete by Research Journal of Recent Sciences ______________________________________________________________ ISSN 2277-2502Vol. 2(11), 20-28, November (2013) Res. J. Recent Sci. International Science Congress Association 28 conducting the early age strength could avoid the situation where the concrete does not reach the required design strength. Since the error is less than 1% the prediction equation allows too fast and accurate prediction of compressive strength values which is eliminating the waiting period for 28 and 90 days results. References 1.Watcharapong Wongkeo, Pailyn Thongsanitgarn and Arnon Chaipanich ., Compressive strength of binary and ternary blended cement mortars containing fly ash and silica fume under autoclaved curing, Adv. Materials Res., 343-344, 316-321 (2012)2.Yan Li, Daosheng Sun, Xiusheng Wu, Aiguo Wang, Wei Xu and Min Deng., Dry shrinkage and compressive strength of blended cement pastes with fly ash and silica fume, Adv. Materials Res., 535-537, 1735-1738 (2012)3.Thanongsak Nochaiya., Watcharapong Wongkeo., Arnon Chaipanich., Utilization of fly ash with silica fume and properties of Portland cement-fly ash-silica fume, Fuel, 89, 768-774 (2010)4.Vili Lilkov ,Ekaterina Dimitrova and Ognyn E.Petrov., Hydration process of cement containing fly ash and silica fume, Cement and Conc. Res., 27, 577-588 (1997)5.B.W.Langan, K.Weng, M.A.Ward., Effect of silica fume and fly ash on heat of hydration of Portland cement, Cement and Conc. Res., 32, 1045-1051 (2002) 6.Mateusz Radlinski, Jan Olek., Investigation into the synergistic effects in ternary cementitious systems containing Portland cement, fly ash and silica fume, Cement & Conc. Comp., 34, 451-459 (2012)7.M.Tokyay., Strength prediction of fly ash concretes by accelerated testing, Cement and Conc. Res., 29, 1737-1741 (1999) 8.BIS 12269-1987, Indian Standard Specification for 53 Grade Ordinary Portland cement, reaffirmed in 2004, Bureau of Indian standards, New Delhi (2004) 9.ASTM C494/C 494M–11, Standard Specification for Chemical Admixtures for Concrete (2011)10.ASTM C192/C192M-07, Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory (2007)11.ASTM C 684 – 99 (Reapproved 2003), Standard Test Method for Making, Accelerated Curing, and Testing Concrete Compression Test Specimens (2003) 12.BIS: 516 -1959, Indian Standard Methods of tests for Strength of Concrete (2008) 13.Ahmed El-Tayeb Ahmed., An accelerated test for predicting the 28-day compressive strength of concrete, Arabian Journal for Science and Engineering, 15, 27-32 (1988) 14.Ali Behnood., Hasan Ziari., Effects of silica fume addition and water to cement ratio on the properties of high-strength concrete after exposure to high temperature, Cement & Conc. Comp., 30, 106-112, (2008)