Assessing sulfuric acid resistance in sustainable GGBFS-cement composite

Concrete's alkali characteristic makes it susceptible to attack by acidic solutions. Concrete degradation caused by sulfuric acid is a global issue that costs billions of dollars annually. Also, the negative implications of cement production urge using supplementary cementitious materials to produce more durable and sustainable binding materials. Therefore, this study addresses these challenges by investigating the durability and sustainability of blended cement with ground granulated blast furnace slag (GGBFS) as a partial substitute when subjected to a 5% sulfuric acid solution to identify chemical durability performance. The weight loss and mechanical properties were measured and compared to the control mixes. The effect of different mixture design parameters, including water/binder (w/b) ratio, GGBFS replacement content, and polycarboxylate superplasticizer content, on cement mortar's resistance to sulfuric acid was investigated. Experimental results revealed that the weight loss was adversely proportional to the GGBFS replacement content. Moreover, the weight loss was inversely related to the polycarboxylate superplasticizer content at the ratio of 0.4 w/b, while it was directly proportional at 0.44 and 0.48 w/b ratios. SEM analysis revealed that the properties and behavior of cement-GGBFS mortar mixtures can significantly be altered by sulfuric acid attack, leading to changes in microstructure and the formation of different hydration products. The findings of this study show that incorporating GGBFS with appropriate superplasticizer amounts can reduce the carbon footprint of GGBFS blended cement.