Effect of low air pressure on the durability of concrete

Severe environment in plateau regions plays a significant role in the mechanical property and durability of concrete. In this study, an environmental control system was designed to simulate the severe environment in plateau regions. Low air pressure as a new factor was examined to explore its effect on the properties of concrete. The effect of low air pressure ranging from 51 to 101 kPa on the compressive strength and durability of concrete with water/cement ratio of 0.46 was studied. It has been observed that low air pressure could reduce the compressive strength and the durability of concrete, including permeability, deicer salt scaling, water variation and water absorption, especially after 28 days. The mercury intrusion porosimetry (MIP) results exhibited that the total porosity and number of pores in the range of 500-1000 nm increased with a decrease in air pressure. A wider gap between aggregate and matrix under lower air pressure was observed in SEM (Scanning Electron Microscopy) analysis. The observed results of compressive strength, water absorption, deicer salt scaling and mass variation on air pressure were approximately linear.