The addition of carbon fiber can change plain concrete (PC) to a quasi‐ductile material and improve its flexural properties through sharing the tensile stress transduced from concrete matrix. However, the influence rule and its mechanism of air entrained by carbon fiber on properties of concrete with different water to cement ratios (W/C) is not clear at present. Therefore, this research aims to explore this influence rule and mechanism. Eighteen kinds of concrete samples with W/C of 0.25, 0.3, and 0.45 including 216 specimens in total were studied. Their mechanical and permeability‐related properties were tested, and carbon fiber's air‐entraining models were established. The results show that carbon fiber has effect of improving the flexural strength, compressive strength, and impermeability of concrete with W/C of 0.25, but when W/C increases, the effect of carbon fiber on improving the flexural strength, reducing the compressive strength and impermeability of concrete increases. The calculation results of the air‐entraining models suggest that one possible air‐entraining mechanism of carbon fiber can be summarized as that carbon fiber entrains more air into concrete as W/C increases, and another one can be summarized as that the air entrained by carbon fiber increases the connectivity of the pore structure of concrete.

中文翻译：

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碳纤维对不同水灰比混凝土的性能及其引气模型的影响

碳纤维的添加可以将普通混凝土（PC）变为准延性材料，并通过共享从混凝土基体传递来的拉应力来改善其抗弯性能。然而，目前尚不清楚碳纤维夹带的空气对水灰比（W / C）不同的混凝土性能的影响规律及其机理。因此，本研究旨在探讨这种影响规律和机理。研究了W / C为0.25、0.3和0.45的18种混凝土样品，总共216个样品。测试了它们的机械性能和渗透性相关特性，并建立了碳纤维的引气模型。结果表明，碳纤维具有改善W / C为0.25的混凝土的抗弯强度，抗压强度和抗渗性的作用，但是当水灰比增加时，碳纤维对提高抗弯强度，降低混凝土的抗压强度和抗渗性的作用就会增强。引气模型的计算结果表明，碳纤维的一种可能的引气机理可以概括为：随着W / C的增加，碳纤维将更多的空气引入混凝土，而另一种可以概括为：碳纤维增加了混凝土孔隙结构的连通性。