Role of supplementary cementitious materials in enhancing concrete properties

Importance of pulverised fuel ash and ground granulated blast furnace slag cannot be denied. In this research work, experimentation was carried out to assess various fresh and harden properties of concretes by adding supplementary cementitious materials in both binary and ternary systems. Various concrete samples with mix ratio1:2:4 were prepared to have constant water-binder ratio of 0.50. The test variables included the type and the amount of the supplementary cementitious materials such as class 'F' pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS). Portland cement was replaced with PFA and GGBS up to a level of 60%. Hence, total eight mixes were prepared. The fresh characteristics were investigated in terms of slump, whereas, the harden properties were assessed from the compressive strength. Among all mixes PF46 mix (40% Portland cement + 60% fly ash) named PF (46) showed highest slump showing effect of PFA on workability of concrete. The addition of high volumes of supplementary cementitious materials decreased the compressive strength at early age but this difference was reduced considerably for long term (91 days) results.