Study on the protective performance of metakaolin-based foam geopolymer (MKFG) as a sacrificial cladding under internal blast mitigation

In this study, experiment and numerical simulation are carried out for the metakaolin-based foam geopolymer (MKFG) as sacrificial cladding in protective structures. The dynamic response of the Rock-MKFG-Concrete Sandwich (RFGCS) structure was investigated by near-field tests. Through numerical simulation, the effects of blast time, sacrificial cladding density and blast equivalent on the energy absorption capacity of RFGCS were discussed. Finally, a four-stage propagation mechanism of the stress wave in the RFGCS structure is established. The results show that the sacrificial cladding reduces the peak pressure in the lining, which prevents the lining from being damaged by excessive reverse tensile waves. With the increase of MKFG density, the protective performance of sacrificial cladding against single blast increases. However, it becomes weak under multiple blasting shocks, which stems from the higher compressibility of MKFG-400. At low blast equivalents, stress wave propagation in superdense (800 kg/m3) MKFG will not induce plastic tensile strain, which results in the tensile energy absorption capacity of MKFG-800 not being fully utilized. As the TNT equivalent increases, the blast resistance of RFGCS is more sensitive to the MKFG lateral stiffness. This is due to when the strain internal energy of MKFG reaches the upper limit, the synergistic anti-deformation effect of MKFG and lining becomes the main means of blast resistance.