Response of Portland Limestone Cement Concrete to High Concentration of Chloride-Based Salts

Portland limestone cement (PLC) is now permitted in the production of all classes of concrete in Canada. Their contribution to reduction in greenhouse gas emissions and sustainable construction is the main driving force for their development globally. However, there has been dearth of information on the effect of PLC on performance of concrete exposed to high concentration of chloride-based salts. Therefore, the aim of this study is to investigate the response, in terms of physico-mechanical properties and microstructural features, of concrete made with PLC without or with fly ash to highly concentrated chloride solutions (NaCl, MgCl2 and CaCl2). A continuous immersion exposure at 5°C was used to promote formation of the complex salts (oxychlorides). The results revealed that PLC mixtures exhibited better resistance to de-icing salts due to synergistic physical and chemical actions of limestone in the matrix. The resistance of concrete exposed to de-icing salts is a function of physical penetrability (magnitude of intruding chloride), amount of aluminate in cement and content of portlandite available for chemical reactions in the hydrated paste. The incorporation of high volume fly ash (30%) had a pronounced effect on improving the concrete resistance to damage as reflected by sound mechanical properties and longevity.