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Modified ASTM C 1293 Test Method to Investigate Potential of Potassium Acetate Deicer Solution to Cause Alkali-Silica Reaction

Following the recent investigations by FAA into premature deterioration of some airfield concrete pavements that were exposed to deicing chemicals, a comprehensive research study was undertaken to examine the role of deicing solutions in causing alkali-silica reaction (ASR) in mortar and concrete test specimens. It was conducted to evaluate the influence of a potassium acetate deicer and anti-icer in causing ASR distress in concrete specimens. A modified ASTM C 1293 test method was employed in this investigation, in which concrete prisms prepared with aggregates of known reactivity were exposed to 50% solution of potassium acetate (KAc) or 1 normal solution of sodium hydroxide (1N NaOH) during the course of testing. Expansion of the concrete test prisms was monitored periodically, along with changes in their dynamic modulus of elasticity. In addition, visual and scanning electron microscopic examinations were conducted on polished specimens at the conclusion of tests. The pH of the deicer soak solution was monitored to detect any changes caused by its interaction with the specimens. Findings from the study indicate that potassium acetate deicer solution is capable of causing significant ASR distress in concrete specimens containing reactive aggregates. A secondary reaction product, composed primarily of a potassium sulfate phase, was observed in prisms containing both reactive and non-reactive aggregates. This product was predominantly found as an infilling in cracks and voids. Additional research needs are identified to help to decipher the precise mechanisms involved in this attack.