Factors affecting the mechanical properties of alkali activated ground granulated blast furnace slag concrete

•Fractional factorial design method was used to analyze the affecting factors.•Five factors each at three levels were considered.•Increase of sodium hydroxide molarity enhanced the mechanical properties.•Increase of sodium hydroxide to sodium silicate enhanced the mechanical properties.•Best results of curing time had been achieved when the curing period is 2 days. This research work aims to study the factors affecting the mechanical properties of alkali activated blast furnace slag concrete. The mechanical properties studied herein were, compressive strength, tensile strength and modulus of elasticity. Five factors each at three levels were considered throughout this research. The effect of sodium hydroxide molarity (10, 12 and 14 M), alkaline solution/slag content (0.40, 0.45 and 0.50), curing temperature (30 °C, 60 °C, 90 °C), curing time (1, 2 and 3 days) and sodium hydroxide: sodium silicate mass ratio (1:1.75, 1:2.50 and 1:3.25) were considered throughout the research program. The fractional factorial method of experimentation was used through the experimental program to reduce the number of mixes. The results generally showed that the increase in sodium hydroxide molarity and sodium hydroxide to sodium silicate enhanced all of the mechanical properties, while the increase in alkaline solution/slag, curing temperature has adversely affected the alkali activated slag concrete. The best results of curing time has been achieved when the curing period is 2 days.