Comparative performance of OPC and LC3-based composites under combined action of carbonation and chloride exposure

Abstract

This study explored the performance of limestone calcined clay cement (LC3) and ordinary Portland cement (OPC) under the combined action of carbonation and chloride ingress. LC3-based paste and mortar were exposed to 20% CO2 and 80% relative humidity at 30 °C. Corrosion mortar samples were also dried and wetted in 7.2% NaCl solution for 13 cycles. Both hydration and pozzolanic reaction products in LC3 were found to decompose at a faster rate. The decalcification due to carbonation altered its pore size distribution with a remarkable increase in pores < 3 nm. The pore-filling effect by the formed CaCO3 improved the compressive strength and nanoindentation modulus of OPC, although no remarkable change was noted for LC3 due to its low Ca(OH)2 content. Depassivation and active corrosion were noted in both binders, but the corrosion activity of LC3 surpassed that of OPC after Cycle 2.