Mechanical properties characteristics of high strength concrete exposed to low vacuum environment

With the development of construction technologies, the concrete structures may be served in low vacuum environment (LVE), such as high-altitude constructions and low vacuum maglev train pipeline and so on. In order to investigate mechanical properties of concrete under LVE, a series of experiments were conducted to compare the compressive strength, flexural strength, and shear strength of high-strength concrete exposed to LVE with that cured in standard conditions. The drying characteristics of concrete exposed to LVE were analyzed, and the influence mechanisms of the LVE on various mechanical properties were discussed. Results show that the compressive strength of specimens exposed to LVE increased significantly, while the decrease in its flexural strength and shear strength were observed. The stronger drying effect caused by LVE resulted in a shrink for hardened pastes, which also further decreased the pore water and increased a larger amount of microcracks formed in the interfacial transition zone within the concrete. Different loading modes have different responses to the microcracks, which results in the difference of mechanical strength of concrete exposed to LVE. This work can provide a new perspective for the knowledge of concrete infrastructure design in vacuum environment.