聚丙烯纤维对渠道矿渣混凝土力学性能影响的研究

Effects of Polypropylene Fibers on the Mechanical Properties of Slag Concrete in Canal Engineering

为降低渠道衬砌混凝土的脆性，将聚丙烯纤维、粒化高炉磨细矿渣、聚羧酸系超塑化剂加入普通混凝土中。共采用体积含量占混凝土的0．1％、0．2％、0．3％、0．4％、0．5％、0．6％、0．7％和0．8％八个掺量的聚丙烯纤维，以及矿渣替代水泥量的35％、45％、55％、65％、75％五个掺量的矿渣组成的21个混凝土配合比。试验结果表明，掺加矿渣和聚丙烯纤维使硬化混凝土密度减小；对于大多数配合比的矿渣混凝土，聚丙烯纤维降低了抗压强度，提高了抗折强度和劈拉强度；其中0．2％～0．4％的聚丙烯纤维和45％～55％的矿渣是最优掺量。进一步以电镜扫描图（SEM）显示的混凝土基体微观结构解释了其宏观力学性能。

To turn the brittle concrete to ductile concrete in canal, 0. 1%,0. 2%,0. 3%,0. 4%,0. 5%, 0.6%,0.7% ,0.8%polypropylene fiber content by volume of concrete as a secondary reinforcement in con- crete, 35%,45%,55%,65%,75% slag as a replacement of cement by weight ,and a new type acid-based polycarboxylate superplasticizer were introduced in concrete. This investigation was designed to measure the effect of the polypropylene content and the introduction of slag into conventional concrete on the mechanical properties including compressive strength, flexural strength and splitting tensile strength. Results showed that mostly the incorporation of polypropylene fibers increased the modulus of rupture, tensile strength, but decreased compressive strength. The addition of slag improved fiber dispersion in the cementitious matrix, causing a significant increment in the compressive strength, tensile strength and flexural strength of the polypropylene fiber reinforced concrete. Overall, 0.2% -0.4% polypropylene fibers and 45%-55% slag are the optimism mixtures, which benefit all mechanical properties of concrete used in canal engineering. Moreover, SEM pictures presented micro-structures of the matrix of polypropylene fiber reinforced concrete containing slag, which explained mechanism of all the macro performances.