Study on Carbonation of Cover Concrete of the Railway Bridges on Qing-Zang Plateau

摘要

The climate of Qing-Zang Plateau in northwest of China is drought and windy with less rain. After the service of about forty years, the carbonation of cover concrete of those bridges is visible and cracks appear gradually due to corrosion of reinforcements resulting in repairing with expensive cost ahead of time. The compressive strength of concrete, and the depth of carbonation of some bridges in arid area were inspected in-site, and the results show that the less relative humidity of environment made the carbonation accelerate with faster rate. Based on the test data and the method of regress analysis, the equation of carbonation life forecast is proposed. The tests of accelerating carbonation were also done in order to investigate the effect of humidity on carbonation, and the reasonable value of depth of concrete cover and the minimum grade of compressive strength of concrete suitable for the bridges in arid area are also discussed in this paper.