Effects of elevated temperatures on properties of concrete containing ground granulated blast furnace slag as cementitious material

Ground granulated blast furnace slag (GGBFS) has been widely utilized as ingredients in concrete due to the advantages of economic, technical and environmental benefits of this material. This paper presents the effects of elevated temperatures on properties of concrete containing GGBFS with replacement ratios of 10%, 30% and 50% by weight of cement. The concrete specimens were subjected to six different elevated temperatures from 150 °C up to 700 °C. Afterward, the mass loss, the carbonation depth, the residual compressive strength and the modulus of elasticity of concrete were determined. Test results indicated that the effect of the temperature on mass loss the GGBFS concrete was less than 8% below 700 °C, which was similar to the ordinary Portland cement (OPC) concrete. The carbonation depth of concrete with high content of GGBFS was greater than that of concrete with lower content of GGBFS. The carbonation depths of GGBFS concrete were about twice of the OPC concrete after exposed to temperatures above 300 °C. The effect of temperatures above 400 °C on the compressive strength of concrete was more pronounced for concrete containing GGBFS. After exposed to 500 °C, the relative compressive strength of concrete with 0%, 10%, 30% and 50% GGBFS was 60%, 62%, 44% and 41% respectively. The modulus of elasticity of concrete reduced significantly when the heating temperature was up to 300 °C, and the reduction was more obvious for concrete containing GGBFS. After exposed to 500 °C, the relative modulus of elasticity of concrete containing 10%, 30% and 50% GGBFS were 22%, 25%, and 27%, respectively, lower than 30% of the concrete without GGBFS.