Hydration Hardening of Early Strength Low-Heat Cement under a Low-Pressure Environment

The limited early strength of low-heat cement (LHC) restricts its extensive application. This work compared the hydration degree, hydration products, and pore structure of the early strength of low-heat cement (ESHLC) in standard (P) and low-pressure (0.5P) curing by XRD, TG, SEM, and MIP. Also, the mechanical strength under different curing conditions was tested and compared. The results showed that compared with standard curing, the hydration degree of the early strength low-heat cement (ESLHC) lessens at 0.5P. Besides, by 90 days, the quantity of AFt had significantly declined, and the C─ S─ H gel displayed a loose cluster-like structure at 0.5P, showing that low atmospheric pressure has the potential to hasten the development of defects in hydration products. The ESLHC paste cured at 0.5 P displayed a coarser pore structure than that cured at P. At last, the low atmospheric pressure adversely affected the ESLHC mortar’s strength. This work delves into the hydration characteristics of ESLHC under low-atmospheric-pressure conditions, providing theoretical support for applying ESLHC in plateau areas.