Effect of low air pressure on the durability of concrete

The use of concrete in the construction of various structures has largely increased owing to their excellent mechanical and durability. Unfortunately, the durability of concrete materials depends on the environment or climatic conditions in which they are used. Therefore, understanding the impact of severe climatic conditions on concrete will be a significant contribution to designing and optimizing high-performance concrete material.

Generally, different environmental conditions have different distinct features that affect the concrete structure in those areas thus resulting in failures. For example, concrete suffers from corrosion in marine regions while those in saline areas undergo rapid deterioration due to saline crystallization pressure. Today, a good number of the world’s cities and major towns are built on plateaus leading to construction of more concrete structures in those areas. A recently published literature indicates that concrete on plateau areas are prone to damage than those in plains. This is attributed to low air pressure in the plateau regions that significantly affect their mechanical and durability properties. Therefore, the effects of low air pressure on the concrete properties have attracted significant attention of researchers.

Recently, Scientists at Harbin Institute of Technology Dr. Xin Ge, Dr. Yong Ge, Dr. Xiaoping Cai, Dr. Wencui Yang, and Dr. Yuanbo Du in collaboration with Dr. Qinfei Li at University of Jinan developed an environmental control system to study the effects of low air pressure in plateau region on the mechanical and durability of concrete materials. Briefly, the authors utilized different tests including compressive strength, water absorption, permeability property and deicer salt scaling to determine the effect of air pressure ranging from 51 to 101 kPa on the properties of the concrete with water to cement ration of 0.46. Eventually, the relationship between the concrete properties and the air pressure were analyzed based on the obtained experimental data. Their work is currently published in the research journal, Construction and Building Materials.

The authors observed that low air pressure significantly decreased the durability and the compressive strength of the concrete and more so after 28 days. Consequently, a decrease in the air pressure resulted in a corresponding increase in the number of pores and total porosity in the range of 500-1000 nm. In addition, an air pressure of 51 kPa led to an increase in the water absorption by 9.42% and 16.7% after 28 and 120 days receptively as compared to the standard air pressure of 101kPa. Therefore, slice concrete absorbed more water than cubic concrete due to high air pressure on the concrete surface.

Generally, a linear relationship was observed between the air pressure and some of the concrete durability properties. Therefore, low air pressure has negative impacts on the mechanical and durability properties of concrete materials. This may accelerate the failure, deterioration of concrete materials and decreased the lifespan of these materials. As such, it would be ideal to consider additional measures such as protection and reinforcement that would be necessary for maintaining the relative humidity inside the concrete. This will thus ensure reduced effects of low air pressure especially in plateau regions that inhabit lots of concrete structures.