The Role of Potassium Acetate Deicer in Accelerating ASR in Concrete Pavements:Relation between Laboratory Field Studies

摘要

About fifteen years after the introduction of alkali acetate and alkali formate deicers into themarket, premature deterioration was observed on some airfield pavements exposed to them.Based on the characteristic map cracking pattern observed on pavement surfaces, this distresswas suspected to be caused by accelerated alkali silica reaction (ASR) induced by repeatedapplications of these deicers. Laboratory-based research indicated that ASR-reactive aggregatesmay undergo active deterioration when intimately exposed to such deicers under conditionspromoting accelerated reaction. This paper describes investigations conducted on cores collectedfrom an airport whose de-icing operations involved repeated application of potassium acetate(KAc) deicer. Detailed microscopic investigation of these cores indicated that more or lessuniform distress existed throughout the depth of the pavement, although in one of them thedistress was due to alkali carbonate reaction rather than alkali silica reaction. However,investigations into the depth of penetration of deicer into these pavement cores showed that onlyvery limited incursion had occurred. A companion laboratory study was performed to estimatethe extent of deicer penetration under different laboratory exposure conditions. The studyrevealed that even in a relatively aggressive wetting and drying exposure regime, the ingress ofthe deicer was very limited. Thus it was concluded that despite the fact that KAc deicer caninduce severe ASR under the aggressive laboratory conditions, penetration into field airportpavements may be so limited that, in some cases at least, the KAc deicer does not appear to bethe primary source of alkalis for the ASR distress observed in the field.