稻壳灰改性铝酸盐水泥的试验研究

摘要

针对铝酸盐水泥中后期强度倒缩的问题，进行了稻壳灰作为外掺料改性铝酸盐水泥的试验研究。分别测试了稻壳灰对铝酸盐水泥抗压强度、抗折强度、泌水率及渗透率的影响，并通过XRD分析探讨了稻壳灰的作用机理。结果表明：适量的稻壳灰不仅可以提高铝酸盐水泥的早期强度，还可以有效改善其中后期强度，稻壳灰掺量以15％为佳；稻壳灰的比表面积巨大，其表面可有效吸附大量水分子，改善了铝酸盐水泥的泌水性；稻壳灰的填充效应使硬化浆体中的连通孔隙数量减少，进而改善了铝酸盐水泥的渗透性；稻壳灰活性被激发后可与水化产物发生反应，削弱了发生在水化反应中后期的晶相转变作用，避免了硬化浆体的中后期强度倒缩。%To address the reduction in the compressive strength of aluminate cement ( HAC) in its middle and late stages, we performed an experimental study to modify aluminate cement using rice hull ash ( RHA) as a type of ad⁃mixture. We tested the influence of RHA on the compressive and flexural strengths of HAC, as well as on the bleed⁃ing and permeability of HAC slurry. We used X⁃Ray Diffraction( XRD) to analyze the mechanism by which RHA influences the properties of HAC. The experimental results show that the proper addition of RHA can not only im⁃prove early⁃stage strength but also effectively enhance the middle and late stage strengths of HAC and that the opti⁃mal RHA content is 15%. Many molecules of water can be absorbed on the surface of RHA due to its large specific surface area, which can improve the bleeding property of HAC. The filling effect of RHA can also reduce the a⁃mount of interconnected pores in hardened HAC slurry, resulting in decreased permeability. RHA activity can be stimulated and can chemically react with hydration products to avoid decreases in strength in the middle and late stages of slurry hardening.