A crack detection method for underwater concrete structures using sensing-heating system with porous casing

Abstract Cracks as the commonest defects in concrete structures, will decrease the bearing capacity, stiffness and durability of engineering structures. Therefore, crack detection is very important in concrete engineering. Based on the heat transfer theory, a novel crack detection method for underwater concrete structures was presented, which identified cracks using the difference of cooling rate of heat source before and after cracking. To realize this method, a temperature tracer system composed of a sensing-heating system, a monitoring tube and multiple porous casing tubes was designed. The effects of dimensions, porosity and thermal conductivity of casing tube on monitoring results were studied using numerical simulation, and a set of comparative tests of three kinds of specimens were carried out. The results showed that this crack detection method was effective and feasible, using the casing tube with larger porosity and miner thermal conductivity could improve the identification effects.