Gypsum has been known to regulate cement setting since more than 100 years, whereas the understanding of the physio-chemical mechanism remains incomplete. Here, we investigated the influence of gypsum on elasticity evolution of fresh tricalcium silicate (C₃S) paste through small amplitude oscillation shear method. Isothermal calorimetry, X-ray diffraction, ¹H nuclear magnetic resonance, and zeta potential measurements were performed to explore the corresponding changes in hydration, microstructure, and colloidal interaction. It was found that incorporating gypsum is beneficial for inter-particle agglomeration by significantly weakening electrostatic repulsion force between particles, which accelerates elasticity development in the early period of setting. Although the retardation effect of gypsum on C₃S hydration hinders the further development of elasticity in the later period, the more divergent needle-like calcium silicate hydrate (C-S-H) and the stronger cohesion of the C₃S particle network in presence of gypsum lead to a higher elasticity at the same hydration degree.

自 100 多年以来，人们就知道石膏可以调节水泥凝固，而对物理化学机制的理解仍然不完整。在这里，我们通过小振幅振荡剪切法研究了石膏对新鲜硅酸三钙 (C _{3 S) 浆料弹性演化的影响。}等温量热法，X 射线衍射，¹进行 H 核磁共振和 zeta 电位测量以探索水合、微观结构和胶体相互作用的相应变化。研究发现，加入石膏有利于颗粒间的团聚，通过显着减弱颗粒之间的静电斥力，加速凝固初期的弹性发展。虽然石膏对C ₃ S水化的阻滞作用阻碍了后期弹性的进一步发展，但在石膏铅存在下，针状水合硅酸钙（CSH）越发散，C ₃ S颗粒网络的凝聚力越强在相同的水化度下，弹性更高。