Dissolution and early hydration of tricalcium aluminate in aqueous sulfate solutions

Abstract

The great reactivity of tricalcium aluminate (C₃A) with water and subsequent rapid precipitation of insoluble products are serious challenges to learning how salts affect its interfacial chemistry and physics during dissolution. Those challenges are addressed here with rapid in situ surface nanotopography monitoring and characterization of hydration products as C₃A dissolves in aqueous sulfate solutions (Na₂SO₄, MgSO₄, and CaSO₄) with varying pH. These measurements shed light on how pure dissolution and early hydration of C₃A are influenced by sulfates. Bulk dissolution experiments confirm a cation-specific effect of sulfates on the inhibition of C₃A dissolution and of etch pit evolution. Soon after the initial contact with sulfate solutions, precipitation of hydration products occurred and the morphology and composition of products were strongly affected by the types of sulfates.