Abstract：The high temperature damages of concrete were investigated by measuring residual strength, chloride permeability and ultrasonic velocity of concrete after exposing to different high temperatures. The test results show that the strength of concrete increases firstly, and then decreases with the increase of temperature. However, the unstable state chloride ion transportation coefficient increases, and the durability of concrete decreases continuously with the increase of temperature. At the temperature of 800℃, the concrete still keeps some residual strength but no durability. The ultrasonic velocity in concrete also decreases with the rising of temperature. A remarkable correlation is presented between the ultrasonic velocity, the residual strength and the durability. Based on the test results
of ultrasonic velocity in concrete, two formulas are proposed to assess the residual strength and the durability of concrete.
2014, Vol. 35 
