Investigation of a Concrete Blistering Failureby R. S. Rollings, Waterways Experiment Station, Vicksburg, United States,
G. S. Wong, Waterways Experiment Station, Vicksburg, United States,
Abstract: During construction of a concrete pavement at a military airfield, numerous small blisters formed on the concrete surface behind the slipform paver and were filled by the contractor using epoxy injection. This paper describes the investigation into the causes of the blisters and the need to repair them. The investigation found that the concrete being placed used an unusually high sand content that was difficult to place and consolidate. The blisters were formed by rising bleed water and air that because trapped beneath the concrete surface following placement by the slipform paver. These blisters were likely to break under aircraft traffic, and therefore needed to be repaired by some manner. The epoxy injections appeared to be adequate. As part of the investigation into the soundness of the epoxy repairs, it was discovered that the concrete itself was not durable under freezing and thawing. Further examination of other projects at this base that had used similar high sand content concrete mixtures found most of them were also not durable. Apparently, conventional air content quality control tests with these sticky mixes included large amounts of entrapped air so that the dosage of entraining agent and resulting air entrainment was too low to maintain an adequate spacing factor for durability.
Subject Headings: Airport and airfield pavements | Concrete | Concrete pavements | Air quality | Epoxy | Material failures | Failure analysis
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