Reactivity Index and Strength Development of High Strength Concrete with GGBFS Cement

Abstract

The slag cement industry in Indonesia is growing in tandem with the smelter industry as a supplier of slag material. The use of slag cement instead of ordinary cement can reduce CO2 emissions. This research aimed to design the mixture composition of slag cement and ordinary cement for high-strength concrete. Standard concrete cylinders and concrete beams were tested to gain the compressive, tensile and flexural strength. The testing results indicate that generally, the concrete mixture compositions of low GGBFS (25%) gained their optimum strength at the age of 28 days while concrete with high composition of GGBFS (55%) achievedsimilar strength at the age of 90 days.A mixture using higher percentage replacement of GGBFS might attain its optimum strength at the longer ages. The use of Silica Fume (SF) in high-strength concrete mixtures with GGBFS found ineffective to increasethe concrete strength as the results indicate that concretes with SF have lower strength compared with non-SF concrete mixtures.