Blast resistance of ECC and composite slabs subjected to near-field explosion

Due to the unfavorable blast resistance of reinforced concrete (RC) slabs, particularly with the frequent occurrence of penetration and spalling damage, engineered cementitious composite (ECC) provided a promising alternative for enhanced blast resistance through its direct application as a building material or by reinforcing existing RC slabs due to its excellent tensile ductility and toughness. In the present study, the blast resistance of the RC slab, the ECC slab, and the composite slab (RC slab reinforced by ECC layer) was investigated and compared through experimental and numerical approaches. Firstly, the material properties of the ECC were acquired through the quasi-static compressive test, as well as quasi-static and dynamic tensile tests, which felicitated the parameter calibration in the K&C model for ECC. Then the numerical models of the RC slab, the ECC slab, and the RC/ECC composite slab were established and validated with the blast test results. The test and numerical results showed that the ECC and composite slabs exhibited superior anti-blast performance in terms of failure mode, damage extent, and load mitigation compared to the RC slab. Owing to the remarkable ductility and toughness, the ECC and composite slabs could greatly reduce the possibility and severity of penetration and spalling damage. Furthermore, five significant parameters impacting the blast resistance of ECC and composite slabs were summarized through dimensional analysis including the tensile strength of ECC σ_t, the total explosive energy Q, the standoff distance R, the slab thickness H, and the slab span L. Then a dimensionless number was proposed to determine the failure mode and predict the residual deflection at the center of the ECC and composite slabs. The results could serve as a reference for the design of ECC and composite slabs to resist blast loading in the field of structural protection.