The objective of this study was to determine if/how magnesium chloride (MgCl₂) influences the durability of typical sidewalk concrete being used in Ontario. The effects of MgCl₂ on deicer salt scaling were reviewed with the hypothesis that MgCl₂ at higher concentrations will cause more scaling. When the early results were inconclusive, the focus of this reearch was then moved to determining if initial exposure to NaCl was a contributing factor, and if the mechanism causing deterioration was due to exposure at high temperatures rather than low temperatures. Mortar specimens were examined for the influence of MgCl₂ on expansion and compressive strength. It was found that MgCl₂ had little effect on deicer salt scaling, but caused an increase in expansion and a decrease in compressive strength with increased MgCl₂ concentrations.