Micro-structural Examination of The Effect of Sulfate on Cement Mortars with Blast Furnace Slag Substitution

Sulfate is a major chemical threat to concrete and reinforced concrete structures. In this study, a micro-structural analysis of the effects of sulfate on cement mortars with blast furnace slag substitution was conducted. To observe the effect of blast furnace slag on cement mortar, blast furnace slag substitution was made instead of CEM I 42.5 R cement at different ratios. Micro-structures of samples cured in potable water and 10% Na2SO4 solution for 2, 7, 28, 90 days were analyzed. A comparative chemical analysis of the samples, C-S-H (Calcium Silicate Hydrate), CH (Calcium Hydroxide) and Ettringite developments were presented. As a result, it was observed that CH gels develop in 7 day samples, C-S-H gels in 28 day samples, and ettringite in samples cured in % 10 Na2SO4 solution for 90 days