Study On High Performance Air Entrainment Concrete In Atmospheric Pressure Steam Curing

With the increase of fixed number of year and influence of the circumstance condition, railway concrete construction was faced with severe concrete durability problem. It was shown in study that by moderately added air entraining agent in concrete would obviously enhance the concrete durability. Different countries have different views in whether or not to entrain air in concrete, especially in prestressed reinforced concrete. In our country's criterion, entrain air in prestressed reinforced concrete was forbidden in public proclamation. Due to this condition, this paper studied some problems on high performance air entrainment concrete in atmospheric pressure steam curing.It is shown in theory that the percentage of expansion concrete was linear with the air quantity in concrete after concrete cure in steam. The air bubbles, which were entrained by air entrain agent, made little damage to inner concrete construction. As long as precured period of fresh concrete was sufficient, the air bubbles would not make any disadvantage. At the same time entraining air in concrete improved the bleeding and isolation in concrete, the long team performance and durability of concrete were improved obviously.It is shown through test results when concrete was curing in 50°C and the air content maintained 4% or so, the percentage expansion and pore constructer parameters have few changes. At the condition of compression strength change little, the bending strength of concrete was obviously increased. The air entraining concrete's shrinkage and creep were less than concrete which not content air entrained agent, and the durability performance was improved obviously.