硅灰对硫铝酸盐水泥水化行为的影响机理

通过抗压强度、凝结时间、电阻率测定以及X射线衍射(XRD)、扫描电镜(SEM)和孔溶液分析,研究了掺硅灰硫铝酸盐水泥浆体的水化行为.结果表明:5%掺量(质量分数,下同)的硅灰可以很好地改善水泥浆体的抗压强度,10%硅灰掺量的试样抗压强度只在1,28d时稍高于空白试样;掺入硅灰明显缩短了硫铝酸盐水泥的凝结时间;硫铝酸盐水泥的主要晶体水化产物是钙矾石,28d时的钙矾石量稍高于3d时,掺硅灰试样的钙矾石量要高于空白试样;掺硅灰试样的电阻率变化曲线高于空白试样,表明硅灰的掺入能够加快水泥的水化速率;硬化水泥浆体的孔溶液碱度随着硅灰掺量的增加而降低,掺硅灰试样的Ca2+浓度高于空白试样,表明硅灰促进了熟料的溶解,5%硅灰掺量试样的Al 3+浓度最低,表明其促进水化的效果更明显.

Influence of Silica Fume on the Hydration Behavior of Calcium Sulphoaluminate Cement

The hydration behavior of calcium sulphoaluminate cement blended with silica fume were investigated through the compressive strength test, setting time test, electrical resistivity test, X ray diffraction(XRD), scanning electron microscope(SEM) and pore solution analysis. The results show that addition of mass fraction of 5% of silica fume increases the compressive strength of cement pastes, while addition of mass fraction of 10% of silica fume results in a higher compressive strength than that of the control sample after 1d and 28d. The setting time of calcium sulphoaluminate cement blended with silica fume is shortened. The XRD results show that the main crystal product of calcium sulphoaluminate cement is ettringite, and content of ettringite after 28d is slightly higher than that after 3d. The electrical resistivity of calcium sulphoaluminate cement blended with silica fume is higher than that of the control sample, which indicate that the hydration of calcium sulphoaluminate cement is promoted. The alkalinity of pore solution of sulphoaluminate cement pastes is decreasing with the increase of silica fume. Change of concentration of Ca2+ in the pore solution indicates that the silica fume promotes the dissolution of sulphoaluminate cement clinkers. From the lowest concentration of Al3+ it is shown that the mass fraction of 5% of silica fume promotes the hydration more obviously.