内养护对不同细度水泥制备的砂浆性能的影响

研究了饱和轻骨料内养护对不同细度水泥配制的砂浆自收缩、强度、水化程度、显微硬度以及界面过渡区形貌等的影响。结果发现：内养护可显著降低不同细度水泥配制的砂浆的早期自收缩,但减缩效果随着水泥比表面积增大而降低;内养护的砂浆后期自收缩仍持续增加,水泥越粗,自收缩后期增长越大;内养护能够显著促进水泥早期水化,这种促进作用在细水泥中最显著。在相同条件下,轻骨料的引入对砂浆强度的影响作用与水泥细度有关;显微硬度以及界面过渡区微观形貌结果显示,轻骨料内养护能显著改善粗水泥体系微观结构,对细水泥体系微观结构的改善则无显著贡献。

Influence of Internal Curing on Properties of Cement Mortars Prepared from Different Fineness Cements

The influence of internal curing (IC) with pre-saturated light weight aggregate (LWA) on the properties of cement mortars prepared from three different finenesses cements was investigated. The corresponding experiments for the autogenous shrinkage, strength, hydration degree, microhardness and microstructures of interfacial transition zone (ITZ) were conducted. It was shown that the IC could reduce the early-age autogenous shrinkage of cement mortars, and the finer cement could give the lower shrinkage re- duction. Nonetheless, the long-term autogenous shrinkage of internally cured cement mortars had a considerable development, especially for mortar with the coarser cement. The IC could promote the hydration of cement at early age, and the promotion was more significant for the finer cement. The effect of IC on the compressive strength of mortar was correlated to the cement fineness under the same internal curing condition. In addition, the results of microhardness and ITZ microstructure of cement pastes indicated that the IC-LWA could favor the improvement of microstructures for the coarser cement systems, but it could not have any the improvement for the finer ones.