Heating Conditions On The Physical And Mechanical Properties Of Concrete

With the increase of concrete strength lever in use, the damage and spalling of high-strength concrete under high temperature has received more and more attentions, and some conclusions about spalling and residual strength of concrete have gained, but some phenomena are still not interpreted well.To clarity the mechanism of spalling and changes of the mechanical performance of concrete after heating, this paper reports a study of influencing factors to mechanical behavior of concrete exposed to high temperature, including heating regulation(heating rate, maximum temperature and holding time), water state and original strength. Spalling mechanism is also analyzed. The result shows:1. The C80 and C40 concrete of 100% water content will spall on fire, the concrete of each strength lever of 0% water content will not spall in three heating rates (fire, 1℃/min and 10℃/min).2. The C80 fine-aggregate concrete will not spall if water content is less than 10%, Nor does the C40 fine-aggregate concrete when water content is less than 20%. The higher the strength of concrete, the lower the limit of water content of spalling. When the water content of concrete is higher, the temperature of spalling will be lower.