Wang Jialei, Hu Xiaoqing, Jiang Feifei, Chen Haoyu
School of Civil Engineering and Architecture, NingboTech University, Ningbo 315100, China.
School of Mechanics & Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China.
Materials (Basel). 2024 Nov 15;17(22):5594. doi: 10.3390/ma17225594.
Reactive rice husk ash (RHA) is used as a supplementary cementitious material (SCM) to prepare cement composite pastes. The impact of RHA content and the internal curing effect on the hydration process of the cementitious system was studied. The hydration heat, degree, and product content of the cement-RHA composite system at 3, 7, and 28 d were analyzed using hydration microcalorimetry, thermogravimetry, and XRD (Rietveld) analysis. The results show that with the increase in RHA, the main exothermic peaks move forward, and the values increase. The induction period is prolonged, and the acceleration period is shortened. The induction period of 15% RHA is extended to 3 h. The hydration heat of cement composite pastes is mainly divided into three stages. Namely, the first stage (0-18 h) is the superposition of the RHA nucleation effect and chemical effect, the second stage (18-51 h) is the superposition of the dilution effect and internal curing effect, and the third stage (51-72 h) is the internal curing effect with the water-release. The internal curing effect of RHA has a certain periodicity, which is related to its content. The water-release age in the early stage (24 h) advances with the increase of content, and the water-release effect in the later stage (7-28 d) is also significant with the increase of content. The higher the content, the more significant the promotion of the internal curing effect on cement hydration and the pozzolanic reaction of RHA.
活性稻壳灰（RHA）被用作辅助胶凝材料（SCM）来制备水泥复合浆体。研究了RHA含量和内部养护效果对胶凝体系水化过程的影响。使用水化微量热法、热重分析法和XRD（Rietveld）分析法分析了水泥 - RHA复合体系在3、7和28 d时的水化热、水化程度和产物含量。结果表明，随着RHA含量的增加，主要放热峰前移且数值增大。诱导期延长，加速期缩短。15% RHA的诱导期延长至3 h。水泥复合浆体的水化热主要分为三个阶段。即第一阶段（0 - 18 h）是RHA成核效应和化学效应的叠加，第二阶段（18 - 51 h）是稀释效应和内部养护效应的叠加，第三阶段（51 - 72 h）是伴随水分释放的内部养护效应。RHA的内部养护效应具有一定的周期性，这与它的含量有关。早期（24 h）的水分释放龄期随含量增加而提前，后期（7 - 28 d）的水分释放效果也随含量增加而显著。含量越高，内部养护效应对水泥水化和RHA火山灰反应的促进作用越显著。
