Influence of Mixture Proportion and Curing Condition on Contribution of Fly Ash to Strength of Concrete

Abstract:

To investigate the strength efficiency of fly ash in concrete, the contribution of fly ash to strength, k value was calculated with the equation: the strength difference between fly ash concrete and control concrete with no fly ash due to the different fly ash content divides by the strength difference between both control concrete with no fly ash due to the different cement content which equals to the former different fly ash content. The k values were organized with fly ash specific surface area, concrete curing condition and age of specimens. Based on a large number of data collected from several proceedings and journals published in Japan during 1981 to 2003, the influences of fly ash property, mixture proportion and curing condition on k value were investigated. Within the range of study the following observations were made: (1) When fly ash concrete kept in moist curing, the k value of fly ash with specific surface area from 250 to 500 m2/kg is averagely 0.5 to 0.6 or higher at an age of 91 days and later, whereas that of fly ash with specific surface area from 150 to 250 m2/kg is around 0.4 to 0.5, and with some cases contributing little to the strength. (2) In the range of a portland cement content of 250 to 450 kg/m3, the strength contribution tends to increase as the cement content increases. (3) The contributions of fly ash to strength at 91 and 364 days are 1.44 to 1.97 times as large as those at 28 days, respectively, by standard curing, but conversely decrease to 0.75 to 0.79 times those at 28 days by air curing.

• Periodical: Key Engineering Materials (Volumes 302-303)
• Pages: 235-241
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.302-303.235
• Online since: January 2006
• Authors: F.-R. Wu, Yoshihiro Masuda, S. Nakamura, S. Sato
• Keywords: Compressive Strength, Contribution of Fly Ash to Strength, Curing Condition, Fly Ash (FA), Mixture Proportion

References

[1] F. -R. Wu, Y. Masuda, S. Nakamura and T. Niinuma: Influence of Curing Change on Strength Development of Concrete Using Fly Ash, Proceedings of the Japan Concrete Institute, Vol. 25, No. 1, July 2003, pp.569-574 (in Japanese).

[2] F. -R. Wu, Y. Masuda and S. Nakamura: Influence of Different Curing Conditions on Strength Development of High-Strength Concrete Using Fly Ash, ACI, SP-221, Proceeding of Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag And Natural Pozzolans in Concrete, Las Vegas, May 23-29, 2004, pp.181-194.

DOI: 10.14359/13253

[3] F. -R. Wu, Y. Masuda and S. Nakamura: Strength Efficiency of Fly Ash in High-strength Concrete, Journal of Structural and Construction Engineering (Transactions of Architectural Institute of Japan), No. 587, January 2005, pp.1-6 (in Japanese).

[4] GIHODO SHUPPAN Co., Ltd.: Concrete Handbook (Second Edition), Japan Concrete Institute, 1996, pp.212-213 (in Japanese).