In order to investigate the air-entraining behavior of air-entraining agents under different atmospheric pressure environment and the influence of atmospheric pressure on the air void structures of air-entrained concrete, the foaming ability of three kinds of air-entraining agents (Alkyl sulfonate, Saponin and Polyether) and the air void structures of air-entrained hardened concrete mixed under different atmospheric pressure environment were obtained respectively. The results indicated that the low atmospheric pressure environment weakened the initial air-entraining ability of air-entraining agents. The life cycle of the bubble produced under low atmospheric pressure environment was obviously shorter than that under normal atmospheric pressure environment. The results also illustrated that the bubble stability under low atmospheric pressure environment was weakened which resulted in a large loss of air content. When the amount of air-entraining agent was constant, the number of bubbles of air-entrained concrete mixed under low atmospheric pressure environment was significantly reduced due to the weakened air-entraining ability and the spacing factor was also increased. In addition, the percentage of large air bubble in the air-entrained concrete casted under low atmospheric pressure environment was increased, which resulted in the specific surface area of air bubbles, and it was significantly smaller than that of the air-entrained concrete casted under normal atmospheric pressure environment.

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