偏高岭土在白色硅酸盐水泥混凝土中的效应

Effect of metakaolin in white Portland cement concrete

研究了偏高岭土取代量对白色硅酸盐水泥混凝土性能的影响,测试了白色硅酸盐水泥标准稠度、凝结时间、胶砂强度以及白色硅酸盐水泥混凝土的坍落度和抗压强度,并同硅灰进行对比。采用扫面电子显微镜(SEM)对白色硅酸盐水泥胶砂试件进行了微观形貌分析。试验结果表明:偏高岭土提高了白色硅酸盐水泥的标准稠度,缩短了凝结时间。适量的偏高岭土可以提高白色硅酸盐水泥胶砂强度。偏高岭土取代量10%时,白色硅酸盐水泥3、7、28 d抗压强分别提高了5.2%、9.6%、6.0%。偏高岭土中的活性SiO_(2)和Al_(2)O_(3)能够消耗氢氧化钙,生成C-S-H凝胶,增强水化产物与骨料间的黏结力。偏高岭土对白色硅酸盐水泥混凝土的流动性有不利影响,但有益于力学性能的发展。与硅灰相比,偏高岭土对白色硅酸盐水泥混凝土早期抗压强度更有利。

The effect of metakaolin substitution on the properties of white Portland cement concrete was studied,and the standard consistency,setting time and mortar strength of white Portland cement were tested.The slump and compressive strength of white Portland cement concrete were tested and compared with silica fume.The micro morphology of white Portland cement mortar specimens was analyzed by scanning electron microscope(SEM).The experimental results show that metakaolin improves the standard consistency of white Portland cement and shortens the setting time.Proper amount of metakaolin can improve the strength of white Portland cement mortar.When the substitution amount of metakaolin is 10%,the pressure resistance of white Portland cement at 3,7 and 28 d increases by 5.2%,9.6%and 6.0%respectively.The active SiO_(2) and Al_(2)O_(3) in metakaolin can consume calcium hydroxide,generate C-S-H gel,and enhance the adhesion between hydration products and aggregates.Metakaolin has an adverse effect on the fluidity of white Portland cement concrete,but it is beneficial to the development of mechanical properties.Compared with silica fume,metakaolin is more favorable to the early compressive strength of white Portland cement concrete.