掺再生微粉硅酸盐水泥复合浆体早期水化特征研究

Study on the early-age hydration behavior of recycled powder blended Portland cement paste

采用低场核磁共振技术测试了不同再生微粉掺量硅酸盐水泥浆体在各龄期的横向弛豫信号强度和弛豫时间,并结合扫描电子显微镜,研究了再生微粉对硅酸盐水泥早期水化以及微观结构的影响。结果表明:复合浆体水化过程可以划分为4个阶段,分别是诱导期、加速期、衰减期、稳定期。随着水化时间的推移,复合浆体内部可蒸发水的弛豫时间T2分布向短弛豫时间方向偏移。再生微粉具有较高的吸水性和水分缓释功能,再生微粉掺量较高的样品在水化过程中横向弛豫时间T2始终保持明显的双峰分布。

Low-field magnetic resonance(NMR) technology was applied to measure the transverse relaxation signal intensity and relaxation time of cement paste with different addition of recycled powder,and Scanning Electronic Microscope(SEM) was used to staudy the influence of recycled powder on early stage hydration and micro-structure of portland cement. The results show that the hydration process of the composite slurry can be divided into four stages:induction stage,acceleration stage,attenuation stage and stable stage. As the hydration goes on,the distribution of the relaxation time T2of evaporable water in the composite slurry shifts to the direction of short relaxation time. Recycled powder has a high absorption capacity towards water and then release wa-ter slowly. During the hydration process,the transverse relaxation time T2of the sample with a higher proportion of recycled powder always maintains an obvious bimodal distribution.