Role of Potassium Acetate Deicer in Accelerating Alkali–Silica Reaction in Concrete Pavements

Abstract

About 15 years after the introduction of alkali–acetate and alkali–formate deicers, premature deterioration was observed on some airfield pavements that had been exposed to the deicers. A characteristic map cracking pattern was observed on pavement surfaces that had experienced repeated applications of these deicers, and the suspected cause of this cracking pattern was accelerated alkali–silica reaction (ASR). Laboratory-based research indicated that alkali–silica reactive aggregates may undergo active deterioration when intimately exposed to such deicers under conditions promoting accelerated reaction. Investigations were conducted on cores collected from an airport whose deicing operations involved repeated applications of potassium acetate deicer. Detailed microscopic investigation indicated that uniform distress existed throughout the depth of the pavement, although in one, the distress resulted from alkali-carbonate reaction rather than from ASR. However, investigations on the depth of penetration of deicer into these pavement cores showed only limited incursion. A companion laboratory study estimated the extent of deicer penetration under different laboratory exposure conditions. Even in a relatively aggressive wetting and drying exposure regime, ingress of the deicer was limited. Thus, it was concluded that although the potassium acetate deicer can induce severe ASR under aggressive laboratory conditions, penetration into field airport pavements may be so limited in some cases that the potassium acetate deicer does not seem to aggravate the ASR distress should one already exist.