This paper describes a laboratory study on the influence vitreous calcium aluminosilicate (VCAS), a new pozzolanic mineral admixture, on the properties of fresh and hardened portland cement concrete. The paper provides a relative comparison of the performance of concrete containing VCAS with that of concrete containing silica fume (SF), which is one of the widely used mineral admixtures. It was observed that the addition of VCAS pozzolan increased the slump (improved consistency) of the mixtures, while the addition of SF decreased it. The VCAS pozzolan was found not to have significant influence on the plastic shrinkage cracking potential of the mixtures while SF increased it. The compressive strength development of both the VCAS and SF mixtures were found to be higher than that of the control mixture. The experimental results showed that both VCAS and SF increased the free shrinkage of concrete. The rapid chloride permeability (RCP) values for mixtures with VCAS and SF specimens were significantly lower than those of the control concrete. At equal replacements of cement with either VCAS or SF, the reduction in RCP values was higher for the SF modified mixtures. Incorporation of either VCAS or SF also reduced the sorptivity and moisture diffusion coefficient of the concrete mixtures. This study provides insight into the behavior of concretes containing two high-performance mineral admixtures.
Samenvatting