Improving energy absorption capacity of foam concrete with gradient and layered architecture

The mechanical properties of foam concrete are significantly affected by its failure mode, closely related to its density and height-diameter ratio, and unfavorable failure mode would inevitably adversely affect its mechanical performance. To investigate the effect of density and height-diameter ratio on the failure modes, firstly a quasi-static compression test is carried out on the specimens with four densities (400, 600, 800, and 1000 kg/m3) and four height-diameter ratios (0.5, 1.0, 1.5, and 2.0). Most specimens exhibit unfavorable splitting failure, while only the specimens with low densities or small height-diameter ratios undergo crushing or shear failure. To improve the mechanical performance of foam concrete, especially the energy absorption capacity, measures including layered architecture, density gradient, and split plate are proposed and experimentally examined in the present study. The results show that sufficient density difference between adjacent foam concrete layers is able to effectively mitigate the propagation of cracks so as to significantly improve its mechanical performance. Moreover, steel split plate at the interface of adjacent foam concrete layers is capable of successfully stopping crack development among different layers, demonstrating superior energy absorption capacity. In addition, layer by layer crushing failure mode can be achieved through the synergy of density gradient and split plates to fill the demand of multi-level protection for important structural members.