The use of surface coating in enhancing the mechanical properties and durability of concrete exposed to elevated temperature

• We studied the properties recovery of concrete exposed to elevated temperature.
• With SCC, the compressive strength of concrete exposed to 200–700 °C can recover.
• With SCC, the modulus of elasticity of concrete exposed to 200–700 °C was enhanced.
• With SCC, the carbonation resistance of concrete exposed to 200–600 °C was increased.

An experimental investigation was conducted to evaluate the compressive strength, modulus of elasticity and carbonation resistance after heating of air-cooled concrete coated with surface coating of concrete (SCC). The concrete with water–cement ratios of 0.59, 0.50 and 0.36 were exposed to temperatures up to 700 °C and then they were naturally cooled in the air. Parts of the fire-damaged concrete specimens were coated with SCC and then they were recured in a controlled condition for a total duration of 90 days. After being exposed to elevated temperatures, compared with the uncoated concrete, the compressive strength of concrete with SCC was enhanced sizably. After exposure to temperatures above 500 °C, the compressive strength of air-cooled concrete without SCC could not recover. The modulus of elasticity of air-cooled concrete with SCC was enhanced. After being exposed to temperatures above 200 °C, the modulus of elasticity of air-cooled concrete without SCC decreased after recuring for 90 days. Without SCC, the carbonation depth of air-cooled concrete increased when the concrete was exposed to temperatures above 300 °C. SCC considerably increased the carbonation resistance of concrete exposed to temperatures below 600 °C.