Abstract: The mechanical properties of 54 standard cubes and 27 standard prism C40 self-compacting concrete specimens under natural cooling and water spraying cooling after high temperature were studied, and the apparent characteristics of the specimen and the loss rate after high temperature were observed. The results show that the apparent characteristics of concrete blocks changed significantly at 500℃ under two different cooling methods. After high temperature, the mass loss rate and peak strain increased with the increase of temperature, and the elastic modulus decreased with the increase of temperature. The compressive strength, splitting tensile strength and axial compressive strength of the test block showed a downward trend under the two cooling methods, but these three strengths were lower under the water spraying cooling method.

Key words: high temperature, cooling method, rate of mass loss, self-compacting concrete, mechanical properties