Chloride-induced corrosion propagation of alkali-activated slag mortar with pulverized fuel ash and metakaolin replacements

Abstract

Alkali-activated materials have great potential in reducing CO2 emissions in cement production industry. This study aims to investigate the corrosion propagation performance of alkali-activated slag mortars with various pulverized fuel ash (PFA) and metakaolin (MK) replacements subject to chloride-induced corrosion. The corrosion propagation performances including corrosion potential, corrosion rate and mortar electrical resistivity under wetting and drying cycles in seawater are studied. Scanning electron microscope (SEM), mercury intrusion porosimetry (MIP) and pH value measurement were conducted to analyze the effects of PFA and MK replacements on the relationship between reaction degree, pore structure, pH value and corrosion propagation performances. The results show that the MK replacement can enhance the corrosion propagation resistance of slag-based alkali-activated mortars under high activator concentration while the PFA replacement reduces the resistance to metallic corrosion of alkali-activated mortars. Mechanisms controlling the corrosion propagation are discussed.