Abstract
Over the last few decades the academic and construction community has been faced with the problem of ageing reinforced concrete highway bridges. The durability of such structures is an increasing concern due to the high cost implications of maintenance, the social impact of road closures and the potential dangers of structural failure. Research has shown that it is mainly the chloride ions within the rock salt de-icing chemicals that induce and accelerate the corrosion of concrete reinforcement, resulting in the curtailment of the life-span of such structures. A number of alternative de-icing chemicals have been suggested, but environmental concerns or high production costs have led to limited use of those alternatives. However, acetate-based de-icers, which seem to be environmentally friendly, combined with the research on cost-efficient methods for their production and application, may provide a viable alternative for winter operations on corrosion-prone structures. This study examined the effects of two commercially available acetate-based de-icers, calcium magnesium acetate (CMA) and sodium acetate (NAAC), on concrete reinforcement corrosion. It also investigated their effects on the microstructure and other physical and chemical properties of cement paste and concrete. This was achieved through a number of standard investigative techniques and by maintaining consistency with respect to the materials used, the curing conditions and the exposure regimes employed throughout the investigation. Control specimens were exposed to water and sodium chloride (NaCl). The correlation of the results from the different types of tests provided a comprehensive picture of the way these chemicals interact with reinforced concrete. The two acetate based de-icers tested, proved to be non-corrosive during the period of testing, while NaCl was observed to increase the tendency for reinforcement corrosion, especially in more permeable specimens. Exposure to CMA solutions led to the formation of magnesium hydroxide (brucite) on the surface of samples but no noticeable changes were observed deeper within the specimens. No significant effects were observed in the cement paste microstructure as a direct result of exposure to NAAC.