石粉对高强机制砂混凝土工作性能和力学性能的影响

Influence of stone powder on working and mechanical properties of high-strength manufactured sand concrete

为了研究玄武岩机制砂的石粉含量对高强混凝土工作性能和力学性能的影响,配制不同石粉质量分数(3%,5%,7%,9%,11%)的C70机制砂混凝土,借助核磁共振(NMR)、差热-热重(TG)同步试验以及场发射扫描电镜试验(SEM)研究其力学特性和微观形态.研究结果表明:利用石粉等质量代替机制砂能够配制出满足力学性能要求的高强机制砂混凝土,在保证水胶比不变的情况下,石粉质量分数为5%~7%的混凝土力学性能指标最佳.石粉良好的微集料填充效应与碱性碳酸钙的生成使水化产物C_(3)S和CaCO_(3)微界面区结构更加密实,而Ca(OH)_(2)在CaCO_(3)表面生成大量晶体,致使Ca(OH)_(2)晶粒细化,从而提高界面黏结作用,使得界面过渡区得到明显改善;该研究成果可为高强机制砂混凝土配合比设计中石粉的利用提供理论参考.

In order to explore the influence of fly ash,silica fume and different contents of stone powder on the working and mechanical properties of high-strength manufactured sand concrete,C70 manufactured sand concrete with different stone powder contents(3%,5%,7%,9%,11%)was prepared,with the help of nuclear magnetic resonance(NMR),differential thermal-thermogravimetry(TG)synchronous test and field emission scanning electron microscope test(SEM),to study its mechanical properties and microscopic evolution.The research results show that the high-strength manufactured sand concrete that meets the mechanical property requirements can be prepared by using stone powder and other qualities instead of manufactured sand.Under the condition that the water-binder ratio remains unchanged,the mechanical property of the concrete with a stone powder content of 5%to 7%is the best.The good micro-aggregate filling effect of stone powder and the formation of basic calcium carbonate make the hydration products C_(3)S and CaCO_(3) micro-interface structure more compact,and Ca(OH)_(2) generates a large number of crystals on the surface of CaCO_(3),resulting in Ca(OH)_(2) crystal grains refinement,thereby improving the interfacial bonding effect,so that the interface transition zone is significantly improved.The research results can provide a theoretical reference for the use of stone powder in the design of high-strength manufactured sand concrete mix ratio.