Experimental study on infrared thermal response characteristics of water-bearing concrete under drop hammer impact

The dynamic impact damage of concrete will lead to serious safety accidents, and the water environment will aggravate the degree of damage. In this paper, an infrared monitoring experimental system for drop hammer impact damage of water-bearing concrete was designed and established. The mechanical properties, infrared radiation temperature (IRT) and infrared thermography of concrete impact damage with different soak time were tested and analyzed. The influence of water on the infrared generation mechanism of concrete was discussed. The results show that water has an initial weakening effect on concrete, which weakens the cementation between concrete particles and aggregate strength, resulting in a decrease in concrete strength. Compared with dry concrete, the infrared temperature of water-bearing concrete increased more during impact damage. With the increase of soak time, the average infrared temperature (AIRT) and the maximum infrared temperature (MIRT) of water-bearing concrete decreased. When dry concrete was damaged, tensile cracks were mainly produced and accompanied by heat absorption. When water-bearing concrete was damaged, high temperature shear cracks appeared. The high temperature generated at the moment of impact failure of water-bearing concrete may be caused by the cavitation phenomenon of water in the microscopic pores of concrete during the drop hammer impact and the combined effect of concrete microstructure damage. The research results are of great significance for monitoring and evaluating the stability of the dynamic evolution process of concrete structures.