Effect of fly ash on shrinkage of self-compacting concrete using restrained ring test

Abstract

In recent years, fly ash (FA) has been increasingly used widespread like a mineral admixture for the production of concrete in general and self-compacting concrete (SCC) in particular. Fly ash is an industrial by-product and is generated during the combustion of coal for energy production from the thermal power station. Fly ash is utilized to increase the workability of concrete mixtures and increase shrinkage resistance of the self-compacting concrete. In this paper, the mixture design of the self-compacting concrete with strength grade of 60 MPa is performed with requirement that the workability satisfies the slump flow, T₅₀₀ and the V-Funnel T_V test range from 650 to 800 mm, from 2 to 5 s and from 6 to 12 s, respectively. Besides, fly ash is used to replace cement with content of 15%, 25%, 35% and 50% to evaluate shrinkage resistance. The obtained results showed that using fly ash contents from 25% to 35% to replace cement can ensure workability of the mixture together with high degree of shrinkage restraint. According to ASTM C1581, the evaluation of restrained shrinkage of the self-compacting concrete based on the restrained ring test, this method reduces the testing time but still ensure the reliability.

Keywords:

fly ash; self-compacting concrete; shrinkage resistance; restrained ring test.