Influence of slag composition and curing duration on the performance of slag blends in chloride environments

This study investigated the influence of chemical composition of Ground Granulated Blast Furnace Slag (GGBS) and curing duration on the performance of slag-cement blends; specifically strength and transport properties. Two slags (1 and 2) with Ca/Si ratios of 1.05 and 0.94 respectively, were used to partially replace 30% of a CEM I 52.5R cement. Various tests, including compressive strength, isothermal calorimetry, water absorption, sorptivity, and chloride ingress were conducted on mortar specimens to measure the performance of the slag blends against a CEM I 42.5R cement. The mortar specimens were pre-cured for 7 and 28 days before exposure to a 3% sodium chloride solution. Two different exposure conditions were studied (one in which the samples were submerged completely in the salt solution, and the other in which the samples were subjected to a 6 hr wetting and drying cycle). The results obtained showed similar performance for both slags at longer curing durations; with the more basic slag 1 exhibiting better transport properties than slag 2 for both exposure conditions at shorter curing durations. This suggests that curing duration as well as variation in chemical composition of slags affects the performance of slag blends in chloride environments