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混凝土的抗冻性主要决定于其气泡结构(air void structure)。水灰比通过改变混凝土的毛细孔结构影响抗冻性;引气剂的加入通过改变混凝土的气泡结构来改善混凝土的抗冻性。在一定水灰比下,混凝土抗冻性不仅取决于气泡的平均间距d_0,且与硬化混凝土总含气量及夹杂气泡含量有关。本文用等效平均气泡间距d_e来表征硬化混凝土气泡结构,则实验测得的耐久性指标DF与d_e之间存在很好的相关性。
The frost resistance of concrete is mainly determined by its air void structure. The ratio of water to cement affects the frost resistance by changing the pore structure of the concrete; the addition of the air-entraining agent improves the frost resistance of the concrete by changing the bubble structure of the concrete. At a certain water-cement ratio, the frost-resistance of concrete depends not only on the average spacing d_0 of the bubbles, but also on the total gas content of the hardened concrete and the content of inclusion bubbles. In this paper, the equivalent mean bubble spacing d_e is used to characterize the structure of the hardened concrete bubble. The experimentally measured durability indexes DF and d_e have a good correlation.