Effects of moisture content and heating temperature on the thermal expansion deformation of concrete

The thermal expansion deformation of concrete is significantly influenced by high temperature and moisture content. Before being heated at elevated temperatures of 100 degrees C, 200 degrees C, and 300 degrees C, the initial moisture content of concrete specimens was maintained at 0%, 3.22%, and 6.55%, respectively. The temperature in the furnace was maintained at the constant temperature until the concrete center also reached the target temperatures. The effects of moisture content and heating temperature on the compressive strength, mass loss, the rate of linear expansion (RLE), and the coefficient of thermal expansion (CTE) were analyzed. The difference of the thermal deformation of concrete before and after the furnace was maintained at the constant temperature were compared. The results showed that when the target temperature was 100 degrees C or 300 degrees C, the relatively lower moisture content resulted in a larger thermal expansion behavior. The RLE and CTE of concrete with the moisture content of 3.22% were the largest when the temperature was up to 200 degrees C, and the volume expansion of concrete rapidly increased under this circumstance. After being heated and maintained at the target temperature until the center temperature of the concrete specimen also reached the target temperature, the RLE and CTE of concrete could be increased by 50% and 30%, respectively. Therefore, the holding time of heating temperature significantly influenced the thermal expansion behavior of concrete.