Moisture sorption and macroscopic deformation of hardened cement pastes (hcps) were studied in the first three drying–resaturation (D–R) cycles using low–field ¹H nuclear magnetic resonance relaxometry. Four types of water (interlayer, gel, interhydrate and capillary) were detected in the hcps. In principle, they were sequentially removed from larger to smaller pores during drying with decreasing relative humidity (RH), resulting in shrinkage of the hcps. Unexpected increases in gel and interlayer water contents as well as greater shrinkage during drying from 100 % to 69 % RH were observed, which is believed to originate from the re–arrangement of C–S–H structure. Because of the C–S–H re–arrangement, irreversible shrinkage was detected during D–R cycles. The drying and irreversible shrinkage in each cycle diminished with the D–R number. A lower water–to–cement ratio and higher curing temperature for hcps are beneficial for reducing drying and irreversible shrinkage.

中文翻译：

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硬化水泥浆体在前三个干燥-再饱和循环中的吸湿行为、微观结构变化和宏观变形


使用低场 ¹H 核磁共振弛豫法研究了硬化水泥浆 （hcp） 在前三个干燥-再饱和 （D-R） 循环中的水分吸附和宏观变形。在 HCPS 中检测到四种类型的水 （层间、凝胶、水合物间和毛细管）。原则上，在干燥过程中，随着相对湿度 （RH） 的降低，它们从较大到较小的孔隙依次去除，导致 HCP 收缩。观察到凝胶和层间含水量的意外增加以及干燥过程中从 100 % RH 到 69 % RH 的更大收缩，这被认为是由于 C-S-H 结构的重排。由于 C-S-H 重排，在 D-R 循环期间检测到不可逆收缩。每个循环中的干燥和不可逆收缩随着 D-R 数的增加而减少。HCP 的较低水灰比和较高固化温度有利于减少干燥和不可逆收缩。