Steel Corrosion in Calcium Aluminate Cement Mortar against Chloride

Abstract

Three different types of calcium aluminate cement (CAC) were investigated about their resistance to chloride-induced corrosion of steel. CAC imposed higher corrosion resistance compared with ordinary portland cement (OPC). The corrosion current density in CAC was nearly indicative of the passivity, ranging below 1.0 mA/m2 (6.45 × 10–4 mA/in.2 ) during the entire duration of monitoring. Some rust was slightly formed on the steel surface in a CAC mixture in the visual examination, while the steel reinforcing bars in OPC were severely corroded along the entire surface, with a corrosion current density up to 56.3 mA/m2 (3.63 × 10–2 mA/in.2 ). Additionally, chloride transport was delayed in CAC by a reduction in the surface chloride, accounting for 1.34 to 1.84% by weight of the binder. The chloride binding capacity of CAC was lower but buffering against a pH fall was higher to keep bound chlorides unreactive in the CAC matrix to enhance the corrosion resistance.