Experimental study on the effect of fireproof coating and cooling methods on the mechanical properties of concrete exposed to high temperature

As a thermal barrier at the surface of concrete, fireproof coating can well protect concrete from direct temperature and slow down the damage caused by high temperature inside concrete. In order to study the effect of fireproof coating and cooling methods on the mechanical properties of concrete exposed to high temperature, concrete was heated to 200 degrees C, 400 degrees C, 600 degrees C, and 800 degrees C, and then the concrete was cooled to room temperature by air cooling and water cooling. The effect of fireproof coating on the temperature rise curve and mass loss of the concrete was investigated. The compressive strength and splitting tensile strength of concrete with fireproof coating after high temperature were tested, and the effects of cooling methods and fireproof coating on the mechanical properties of concrete after high temperature were analyzed. The results showed that the nonintumescent fireproof coating can reduce the mass loss of concrete exposed to high temperature. After being exposed to 200-800 degrees C, the compressive strength of concrete with fireproof coating increased by 10.4 %-93.1 % and the splitting tensile strength increased by 24.7 %-70.7 % compared with the concrete without fireproof coating. The compressive strength and splitting tensile strength of concrete with fireproof coating were higher than concrete without fireproof coating. At 600 degrees C, the compressive strength increased by 34.2 % and splitting tensile strength increased by 44.7 %. The compressive strength of water-cooled specimens was obviously lower than that of air-cooled specimens, and the reduction of compressive strength gradually increased with the increase of temperature. At 800 degrees C, the compressive strength of water-cooled specimens was reduced by 43.5 % compared to air-cooled specimens. The splitting tensile strength of water-cooled specimens decreased significantly with increasing temperature, and the splitting tensile strength of water-cooled specimens was lower than that of air cooling after all four target temperatures.