Comparison of Permeability and Drying Shrinkage of Self Compacting Concrete Admixed with Wollastonite Micro Fiber and Fly Ash

Abstract

Cement substitution in self compacting concrete (SCC) is emphasized to conserve environment, reduce cost and utilize waste materials. This paper focuses on comparing the permeability and drying shrinkage of SCC containing Wollastonite micro fiber (WMF), a cheap pozzolanic fiber with respect to flyash. Microsilica was added for providing required viscosity to maintain homogeneity of the mixes. Trials to check flowability, passability and segregation resistance were conducted on binary, ternary and combined mixes of binder material. Results showed that drying shrinkage reduced by 49% for WMF reinforced concrete, whereas it increased by 1.25% for flyash ones as compared to normal concrete. Permeability coefficient decreased by 82% and 74%, respectively. Capillary voids influenced the permeability of hardened concrete, but drying shrinkage was largely influenced by the rate of gain of tensile strength and expanding ettringite. Notably, flyash is not a reliable admixture for controlling drying shrinkage of high flow concretes.