Investigation into Potential of Alkali–Acetate–Based Deicers to Cause Alkali–Silica Reaction in Concrete

Abstract

Recent investigations by the FAA into the condition of airfield pavements have indicated increased occurrence of premature deterioration in concrete pavements, particularly caused by alkali–silica reaction (ASR). On the basis of the evidence, it was suspected that certain deicing chemicals used on the pavements may have been responsible for the distress. This paper presents the results from a study conducted to investigate the effect of potassium acetate–and sodium acetate–based deicers on causing ASR in test specimens. A modified ASTM C 1260 test procedure was used in this study, in which mortar bars prepared with reactive aggregates were soaked in deicer solutions, instead of 1 N sodium hydroxide solution as in the standard ASTM C 1260 test. Tests were conducted on four reactive aggregate sources and one nonreactive aggregate, using a low-alkali and a high-alkali cement. In addition, standard ASTM C 1260 tests were conducted on all aggregates considered in this study. The effect of concentration and temperature of soak solutions on the observed expansions of mortar bars was also investigated. Length-change measurements, dynamic modulus of elasticity, scanning electron microscopy, and energy dispersive X-ray analyses were conducted on test specimens. The pH values of the soak solution were monitored to observe any interactions between the soak solution and the mortar bars. On the basis of this research, it was found that the two common airfield deicing chemicals—potassium acetate–and sodium acetate–based deicer solutions—have a significant potential to cause ASR in test specimens containing reactive aggregates.