Scheme Design and Experimental Study of Selective Thermal Stimulation for Concrete Microcracks Based on IR Thermography

In this paper, we propose a novel detection technology to telemeter microcracks in concrete structures using an infrared thermal imager carried by an unmanned aerial vehicle and explore the thermal excitation method applicable to it. Moreover, this paper presents a selective thermal stimulation scheme design for microcracks in concrete, in which NaAlO₂ and NaHCO₃ solutions, whose temperatures are higher than the air temperature, were chosen as the stimulation sources, and relevant experimental studies were conducted. Simultaneously, the heat generation mechanism from the microcrack stimulation was studied. Thereafter, through the thermal stimulation test of prefabricated microcracks, the effects of different amounts of stimulation reagents and different stimulation times on the detection of microcracks were determined by controlling the variables and discussing each stimulation parameter. Furthermore, the optimum reagent dosage and best detection time window were determined. The actual microcracks on a concrete beam were used to verify the test scheme, and a good incentive effect was obtained.