硅灰预处理对高性能水泥基材料力学性能的影响及其作用机理的研究

本研究进行了一系列的对比试验，旨在提高掺加硅灰水泥基复合材料的强度。研究结果表明，通过采用六偏磷酸钠对硅灰进行预处理，可使掺加硅灰的高技术水泥基复合材料达到了较高的强度性能，其抗压强度可以高达200MPa以上，抗折强度超过30MPa。本文应用Aim-Goff模型探讨了其作用机理，研究显示，加入六偏磷酸钠分散了硅灰的团聚体，提高了水泥基复合材料的堆积密度，从而改善了水泥基复合材料的力学性能。SEM and XRD分析也表明，采用六偏磷酸钠对硅灰进行预处理，改善了水泥基复合材料界面区的结构，减少了Ca(OH)2的含量和降低了Ca(OH)2结晶度，从而提高了水泥基复合材料的强度性能。同时，本研究也表明，纳米级硅灰颗粒具有极强的自团聚效应，改善硅灰的分散性是充分实现其特异的物理、化学特性的关键。

Effect of the pre-treatment of Silica Fume on Mechanics Properties of High-tech Cement-based Composite and its Action Mechanism

A series of comparative experiments aimed at reaching high strength with silica fume were carried out in this work. The results show that the strength of cement-based materials with silica fume is improved through the pre-treatment of silica fume by sodium hexametaphosphate, the compressive strength being more than 200MPa and the flexible strength being over 30MPa. The mechanism was further studied by the particles sedimentation test in combination with DLVO theory and Aim-Goff model. It is concluded that the addition of sodium hexametaphosphate can disperse the agglomeration of silica fume and increase the packing density, thus improve the mechanical performance. SEM and XRD analysis show that the addition of Sodium hexametaphosphate improves the structure of the interface transition zone, reduces the amount of Ca(OH)2 and weakens crystal degree of Ca(OH)2 by the dispersion of silica fume, thus raising the strength of cement-based materials. It is suggested that improving the dispersion of silica fume be the key to fully utilize the potential of silica fume.