纤维增强再生骨料混凝土力学性能试验及公式推导

MECHANICAL PROPERTY EXPERIMENTS AND CALCULATION FORMULAS OF FIBER-REINFORCED RECYCLED AGGREGATE CONCRETE

选取不同纤维制备多种纤维增强再生骨料混凝土试块,测试各项力学性能指标如抗压、劈裂抗拉强度和弹性模量,并与普通混凝土对比;探讨了玄武岩纤维的最优体积掺量,基于试验结果建立玄武岩纤维增强再生骨料混凝土各项力学性能之间关系的换算公式,并推导了力学性能指标计算公式。试验结果表明,由于再生粗骨料的较高吸水率导致实际水灰比降低,使得相同配合比下的素再生骨料混凝土获得了比普通混凝土更高的抗压和劈裂抗拉强度;而掺加纤维并非最优体积掺量及存在散布不均会导致再生骨料混凝土抗压强度下降。此外,玄武岩纤维对再生骨料混凝土力学性能的提升较小,部分性能甚至降低,立方体抗压强度对应最优体积掺量为0.1%,其他力学指标为0.2%。所提出的玄武岩纤维再生混凝土各力学性能指标计算公式准确度较好,具有一定的参考价值。

Recycled aggregate concrete(RAC) reinforced by different type of fibers was prepared for experimental specimens in order to measure the mechanical properties such as compressive strengths, splitting tensile strengths and elastic modulus. The mechanical properties were then compared with those of normal concrete. Meanwhile, the optimal amount of basalt fibers(BFs) to RAC was also investigated and the strength conversion formulas, as well as the calculation formulas for mechanical indices, were deducted based on the experimental measurements. Experimental results demonstrate that under an identical mixture ratio, the compressive strengths and splitting tensile strengths of RAC without fibers could be greater than those of normal concrete due to the fact that the water absorption of recycled aggregates induces a practically lower water-cement ratio. Meanwhile, non-optimal ratios and inhomogeneous distributions of fibers could decrease the compressive strengths of fiber-reinforced RAC. Additionally, BFs showed little contributions to the mechanical properties of RAC and in some cases reduction effect could happen. The optimal amount of BFs to the cubic compressive strengths was 0.1%. However, the optimal amounts to the other three mechanical indices were all 0.2%. Lastly, it was found that the proposed calculation formulas for the mechanical properties of BF-reinforced RAC presented satisfactory performance and thus could be used as a reference in practice.