A study on the potential of deicing chemicals to cause alkali-silica reaction in concrete

Deicers and anti-icers are routinely used for ice and snow removal operations from pavements. Due to certain durability concerns like corrosion and environmental impact associated with regular deicers, airport authorities in the United States and many other countries have started to use special alkali acetate and alkali formate based deicers for removing ice and snow from runways. Recently, there has been an increase in the reported instances of deterioration of airport runways due to alkali silica reactivity (ASR) ASR in concrete and it is suspected that the deterioration may be linked to the use of these special alkali based deicing chemicals.; Currently there are no standard tests available to identify damaging effects of deicing chemicals. This study investigates the potential for acceleration of ASR in the presence of airfield deicing chemicals such as potassium acetate, sodium acetate, sodium formate and potassium formate, it seeks to explain the mechanism of deterioration caused by one of the most widely used deicer, a solution of potassium acetate. A preliminary investigation was carried out to validate the ability of the proposed modified test procedures in identifying deleterious reactions between deicers and aggregates. Standard and modified ASTM C 1260 and C 1293 test procedures were then used to study the influence of selected deicing chemicals on concrete prism and mortar bar specimens. Using tests such as dynamic modulus of elasticity, scanning electron microscopy, energy dispersive analysis, X-ray diffraction, pH measurements and ion chromatography, results were compiled to study the influence of deicing chemicals on durability of concrete and mortars specimens. The results indicated that, alkali-based deicers have considerable potential to initiate and accelerate ASR in concrete containing marginally reactive aggregates.; The study also found that higher temperatures accelerated the expansion of mortar bars in presence of deicing chemicals. However, test conducted at lower temperatures showed significant expansion in mortar bars after prolonged exposure of test specimens. The study also found that the concentration of deicers plays a significant role in causing expansions and deterioration of mortar bar specimens. In particular, with potassium acetate deicers, concentrations at 1 molar and below did not cause significant expansions in mortar bars. Reagent-grade chemicals produced similar or higher expansions than commercial grade deicing chemicals at similar concentrations.