Experimental research on the dynamic mechanical properties and damage characteristics of lightweight foamed concrete under impact loading

As an energy-saving and environmentally friendly building material, foamed concrete has been widely applied for construction against impact loading. To investigate the dynamic mechanical properties and damage characteristics of lightweight foamed concrete under impact loading, a series of impact experiments are carried out on foamed concrete with densities of 300 kg/m(3), 450 kg/m(3) and 700 kg/m(3) under a strain rate range of 60 s(-1)-250 s(-1) by using a split Hopkinson pressure bar (SHPB) device. The stress-strain relationship, elastic modulus, peak stress and dynamic increase factor are discussed and analyzed in detail. The results show that the dynamic mechanical properties of the material exhibit a significant strain rate enhancement effect and density dependence. In addition, the damage characteristics are analyzed quantitatively by fractal calculations of the fracture. The fractal dimension increases markedly with increasing strain rate, and the maximum is 3.57, which indicates that the overall damage is related to the strain rate. For the three different foamed concrete specimens under a strain rate of approximately 130 s(-1), the fractals present a transition behavior. The failure patterns of the foamed concrete are consistent with the fractal characteristics.