The Performance of Concrete Containing Slag as a Partial Replacement for Cement

Abstract

There have been many attempts to examine ground granulated blast furnace slag (GGBS) as partial replacement for cement to improve concrete properties. However, there is a controversy about the proportion of replacement with claiming that a high replacement level might have a negative effect on concrete properties. In this experimental study, the effects of the partial replacement of cement with GGBS varied by 0%, 30%, 50%, and 70% of cement weight on the engineering properties of concrete with a (w/b) of 0.45 were investigated. Workability and set-ting time were used to evaluate the properties of fresh con-crete. Compressive, flexural, and split tensile strength at various curing ages (7, 28, 56 and 90 days) are the mechani-cal properties of concrete being investigated. A porosity test is also performed at the ages of 7 and 28 days to assess the durability aspect of concrete. The main finding was that increasing the replacement level of GGBS increased the initial setting time, which improved the concrete workabil-ity. However, this resulted in a reduction in early strength in comparison to cement type I (CEM I) concrete. Moreover, the partial replacement with 50% GGBS increased the compressive, flexural and tensile strength of concrete at the age of 56 days, whereas partial replacement percentage of 70% GGBS resulted in a lower strength. as a result, the GGBS replacement percentage of 50% might be considered the optimum replacement value. Using a high volume of GGBS in concrete can result in a 40% reduction in concrete voids volume, increasing the resistance of concrete to chemi-cal attack when exposed to severe environmental conditions.