Drying shrinkage of cement pastes (CPs) facilitating superficial cracking deserves primary concern when evaluating durability performance. To clarify shrinkage mechanism, the changes of mass, length and pore-scale water allocation of two mature CPs were monitored non-destructively through low-field NMR relaxometry. Experimental results indicated that, heat treatment under hot water slightly coarsens the pore structure of CPs through modifying ▪ packing, and reduces shrinkage remarkably through stiffening ▪ clusters. Upon drying at 43% RH, the interlayer pores are still saturated and compacted with reduced volume. At 80% RH, although the interlayer and gel pores are both saturated, they lose water gradually at reducing rates. Drying shrinkages of CPs are caused by compaction of interlayer and gel pores, whose contributions to shrinkage are at the ratio of 1:3 roughly. Most of ▪ compaction is compensated by the coarsening of pore structure, and only 2–6 percent shows up as observable shrinkage.

中文翻译：

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C[sbnd]S[sbnd]H 凝胶的变形及其与水泥浆体干燥和再饱和时动态长度变化的联系


在评估耐久性能时，水泥浆 （CP） 的干燥收缩促进表面开裂，值得首要关注。为了阐明收缩机制，通过低场 NMR 弛豫法无损监测两种成熟 CP 的质量、长度和孔隙尺度水分分配的变化。实验结果表明，热水热处理通过改性▪堆积使 CPs 的孔隙结构略微粗化，并通过加强▪团簇显着减少收缩。在 43% RH 下干燥后，层间孔仍然饱和并压缩，体积减小。在 80% RH 时，尽管层间和凝胶孔都已饱和，但它们会以降低的速度逐渐失去水分。CPs 的干燥收缩是由夹层和凝胶孔的压实引起的，它们对收缩的贡献大约为 1：3。▪ 大部分压实由孔隙结构的粗化补偿，只有 2-6% 显示为可观察到的收缩。