Assessment of water absorption and chloride ion penetration of pavement quality concrete admixed with wollastonite and microsilica

Wollastonite with or without microsilica was evaluated as a new material for partial replacement of cement in M40 grade pavement quality concrete. Wollastonite is abundantly available in the Udaipur belt of Rajasthan state in the Indian union as a low cost material. Its physical and chemical properties were analyzed. This particular wollastonite consists of 45.6% of CaO and 48% of SiO2, mainly in amorphous form and has an average specific surface area of 842.7 m2/kg. Five finalized concrete mix proportions including the control mix were investigated for saturated water absorption, rate of water absorption, coefficient of water absorption and chloride ion penetration. Test results indicate that up to 15% of wollastonite and 7.5% microsilica can be advantageously admixed with cement to significantly improve the water tightness of concrete due to reduction in pore space and refinement of microstructure. Mathematical relationships existing between these parameters were studied and predictive graphs were developed.