偏高岭土和钢纤维对混凝土力学性能影响研究

Effect of Metakaolin and Steel Fiber on Mechanical Properties of Concrete

为研究偏高岭土(MK)和钢纤维(SF)掺量对混凝土力学性能和工作性能的影响,将不同体积掺量的SF掺入混凝土中,在SF掺量固定为1.2%时,复掺不同质量的MK,进行新拌混凝土的坍落度和3 d、7 d、28 d龄期试件的立方体抗压强度、劈裂抗拉强度和抗折强度试验,并利用扫描电镜(SEM)进行微观分析。结果表明,掺入SF和MK显著降低混凝土坍落度;SF掺量为1.2%时,力学性能最优,立方体抗压强度、劈裂抗拉强度和抗折强度分别提高10.21%、66.33%和43.16%;在SF掺量为1.2%时,MK掺量在15%、10%和10%时,抗压强度、劈裂抗拉强度和抗折强度最大,相较对照组SF-1.2,分别提高7.45%、6.21%和14.99%;SF在混凝土中起桥接作用,可有效延缓裂缝的扩展,MK可使混凝土内部变得更加密实,从而提高混凝土的力学性能。

In order to study the effect of the content of metakaolin(MK)and steel fiber(SF)on the mechanical and working properties of concrete,adding different volume of SF into the concrete,when SF content is 1.2%,the slumps of the newly mixed concrete and the cube compressive strength,splitting tensile strength and flexural strength of the specimens at the age of 3 d,7 d and 28 d are tested by adding different qualities of MK;At the same time,the microscopic characteristics were analyzed by SEM.The results show that,SF and MK significantly reduce the slump of concrete;When SF content is 1.2%,the mechanical properties are the best,and the cube compressive strength,splitting tensile strength and flexural strength are increased by 10.21%,66.33%and 43.16%,respectively.When SF content is 1.2%and MK content are 15%,10%and 10%,the compressive strength,splitting tensile strength and flexural strength are the highest,which are increased by 7.45%,6.21%and 14.99%,respectively,compared with the SF-1.2 control group.SF plays a bridging role in concrete,which can effectively delay the expansion of cracks,and MK can make the inside of concrete more dense,thus improving the mechanical properties of concrete.