Abstract:To study the properties of Qtech T26 blast-mitigation polyurea (T26 polyurea) and the protective properties and fracture mechanism of T26 polyurea-protected reinforced concrete slabs under contact blast action, dynamic thermomechanical analysis and 10 kg trinitrotoluene (TNT) contact blast tests were carried out. The polymer master curve was fitted based on the Williams, Landel, Ferry equation and a scanning electron microscope was used to analyze the microscopic fracture morphology of typical areas on the blast face and back face of the coated reinforced concrete slab. The results showed that T26 polyurea is significantly influenced by frequency, confirming the strain rate sensitivity of T26 polyurea in terms of its thermomechanical properties. The loss factor of T26 polyurea remains above 0.24 when the external load frequency is greater than or equal to 1000 Hz, resulting in high energy absorption efficiency. The reinforced concrete slab with a 10 mm T26 polyurea coating was damaged by 10 kg TNT contact blast with the back blast surface coating intact and no fragments flying out. T26 polyurea on the blast face was not detached from the concrete, and the adhesion between T26 polyurea and concrete interface was quite good after surface treatment, which means that there was still favorable adhesion between the coating and concrete under the tensile wave generated by the explosion.The fracture mechanism of T26 polyurea under blast loading is characterized by high temperature mechanical property failure mechanism, coupled high temperature and impact loading fracture mechanism, high speed loading brittle fracture mechanism and tensile fracture mechanism. The area of maximum deformation of the backblast surface is the circular area on the outside of the longitudinal deformation area, the central area of the backblast surface is subjected to high strain rate loads during protection and a small amount of brittle damage occurs. T26 polyurea has achieved contact explosion with zero fragmentation protection, showing a great value for structural blast fragmentation protection in practical engineering.