Study On The Assessment Method Of Fire-damaged Concrete

Concrete is known to be the most widely used structural materials that can exhibit quite excellent behaviors under different environmental conditions.Fires can cause great damage to cement concrete materials.Fast and accurate assessments of fire damaged concrete structures are of great significance for later maintenance and reuse.However,the assessment is difficult to conduct due to the complex components of concrete and the inconsistent fire damage degree in a concrete structure.The traditional methods such as apparent observation method and the formula method can only assess fire damaged concrete qualitatively rather than quantitatively.And the rebound test and the carbonization test require large amount of experimental efforts.Meanwhile,some other new technologies like the thermal analysis method and core drilling method may cause further damage to concrete structure and their applicability still needs further investigation.This paper will study colorimetry method,infrared thermal imaging method and ultrasonic method on assessing fire damaged concrete under different conditions.Fire damage experiment was first conducted on concrete cubes with two different strengths.Concrete cubes were heated for 1h and 3h to study the influence of heating duration.And the concrete cubes were cooled down by air and water to study the influence of cooling method.The color of concrete,the average surface temperature rise and the ultrasonic propagation speed in concrete have a good correlation with the maximum temperature that concrete was subject to.Quantitative formulas can be established to detect the degree of concrete damage caused by fire.The results of this study will add and advance the technology for assessing fire-damaged concrete.