Shrinkage of concrete refers to the volumetric change of concrete due to cement hydration (i.e., self-desiccation) and environmental drying (i.e., water evaporation). It creates dimensional instability and induces tensile stress when the concrete is restrained that may be large enough to cause cracking. The most fundamental way to mitigate concrete shrinkage is to decrease the shrinkage of cementitious paste in the mix design. Some major factors of concrete mix design affecting the shrinkage include water-to-cementitious material (W/CM) ratio, dosage of superplasticizer (SP), concrete strength, and cementitious paste volume (CPV). While the effects of concrete strength and CPV on shrinkage are straightforward, those of W/CM and SP are more complicated because they also affect the pore size and distribution that influence the moisture movement. In this paper, it is advocated to study the concrete shrinkage by its wet packing density (WPD). Considering that the shrinkage of concrete is associated with the moisture movement in capillary pores and that the WPD accounts for the void ratio in fresh concrete, it will be shown in this paper that the shrinkage can be correlated negatively to the WPD with the consideration of CPV. The paper thus provides a new insight to the interdependence amongst shrinkage, CPV, and WPD of concrete.

中文翻译：

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混凝土的收缩率、胶凝体体积和湿堆积密度

混凝土收缩是指由于水泥水化（即自干）和环境干燥（即水分蒸发）引起的混凝土体积变化。当混凝土受到约束时，它会产生尺寸不稳定性并引起拉伸应力，该应力可能大到足以引起开裂。减轻混凝土收缩的最基本方法是在配合比设计中减少水泥浆的收缩。影响收缩率的混凝土配合比设计的一些主要因素包括水胶比 (W/CM)、高效减水剂 (SP) 的用量、混凝土强度和胶凝浆体体积 (CPV)。虽然混凝土强度和 CPV 对收缩的影响很简单，但 W/CM 和 SP 的影响更为复杂，因为它们也会影响影响水分运动的孔径和分布。在本文中，提倡通过湿堆积密度（WPD）来研究混凝土的收缩。考虑到混凝土的收缩与毛细孔中的水分运动有关，并且 WPD 占新拌混凝土的空隙率，本文将表明在考虑 CPV 的情况下，收缩与 WPD 呈负相关. 因此，本文为混凝土的收缩率、CPV 和 WPD 之间的相互依赖性提供了新的见解。本文将表明，考虑到 CPV，收缩率与 WPD 呈负相关。因此，本文为混凝土的收缩率、CPV 和 WPD 之间的相互依赖性提供了新的见解。本文将表明，考虑到 CPV，收缩率与 WPD 呈负相关。因此，本文为混凝土的收缩率、CPV 和 WPD 之间的相互依赖性提供了新的见解。