Effect of Silica Fume Addition on The Mechanical Properties of Concrete

Abstract

Although the practice of using supplementary cementitious materials (pozzolan) such as silica fume in concrete mixtures has been growing in since the 1970s, no enough information is published addressing the optimum replacement percentage that can produce a well performed concrete. Thus, the current experimental study was carried out to investigate the effect of silica fume (SF) replacement (5, 10 and 15%) on mechanical properties of concrete for water to binder ratios ( 0.5 ). Performance of silica fume concrete specimens was compared to specimens made with CEMI (42.5 N). Compressive , flexural strength and split tensile strength were evaluated at 7, 28, 56 and 90 days of curing. Workability of fresh concrete mixes was assessed using a slump test. The carbonation depths were also tested using 100 mm cube specimens at 90 days of curing. Replacement of cement by silica fume reduced the workability of concrete and increased the water demand. On the other hand, improvement in the compressive, flexural and tensile strength of concrete was noticed as the replacement by silica fume increases. Replacement of cement by 15% SF showed highest compressive flexural and tensile strength by about 41.8, 37.8 CEMI concrete mixes at age of 90 days.