Infrared radiation precursor and energy dissipation properties of water-containing concrete under impact load

Concrete structure is often in an aqueous environment, and it will be subjected to impact load when the vehicle passes. Infrared radiation can reflect the concrete crack development and energy dissipation. To reveal the effect of water and impact load on infrared radiation of concrete, this paper studied the time-varying law of infrared response of concrete with diverse soaking time under dynamic load damage, and quantitatively analyzed the infrared thermography properties of concrete impact failure process by infrared thermal image frequency distribution histogram. The results show that the infrared radiation temperature increment of water-containing concrete was inversely proportional to the soaking time. Its Delta Tmax and Delta Tave are 1.6 - 7.5 times and 1.4 - 5.4 times that of dry concrete, respectively. The peak proportion of high temperature precursors (SH max) and the peak proportion of low temperature precursors (SL max) of dry concrete are almost equal, while the SH max of water-containing concrete is 4.9 - 44.6 times of SL max. When the SH curve begins to rise rapidly or the SL curve begins to fluctuate violently, it can be considered as a precursor to the destruction of concrete. Water affects concrete's infrared radiation response in two ways. As the soaking time increased, the water-containing concrete's absorption energy increased, the SH and SL areas decreased, and the cumulative infrared radiation energy increment and infrared radiation energy conversion ratio decreased. The absorption energy of water-containing concrete was inversely proportional to the cumulative infrared radiation energy increment. The research results provide a feasible method for dynamic failure early warning and structural stability evaluation of watercontaining concrete structures.