Experimental investigation on the behavior of RC panels retrofitted with polymer coatings under blast effects

Abstract

Elastomeric polymers (such as polyurea and polyurethane) are finding relevance in retrofitting applications for structures being subjected to blast and impact loadings. This approach, an alternative to various existing retrofitting techniques, capitalises on the elastomeric properties, high strain capacity, high ductility and strength of the polymers, as well as on the ability of the coating layer to act as a shield in containing debris and fragments from the blast. This paper presents the findings from an experimental study undertaken to evaluate the effectiveness of using polyurea coatings to enhance the blast resistance of reinforced concrete (RC) panels. The performed experimental blast trials, designated as Vietnam Trial 2, were conducted in Vietnam with the collaboration from the Vietnam Institute for Building Science and Technology (IBST). Four RC panels with dimensions of 1700 (L) 1000 (W) 60 (T) mm, were tested during the trials. Of these, one panel was an unretrofitted panel while the remaining three were coated with polyurea albeit with a variation in the coating thickness and location. All the panels were subjected to blast loads resulting from the detonation of 1.0 kg Ammonite charge placed at 1.0 m stand-off. The behaviour and responses of various polyurea coated RC panels were compared to the unretrofitted RC panels in terms of panel’s deflections, crack formation and damage to the polyurea coating layers. The findings from the experiments indicated that proposed technique of using polyurea coating to retrofit RC structural elements is practicable and feasible to enhance the capacity of structures against blast loading. A higher level of protection is provided when the protective coating is applied on the blast-facing face of the structure. It was also observed that the bond between concrete and the polymer did not damage even after the the application of the blast loads. These findings assert the possibility of using the proposed technique as a practical alternative to the existing techniques in strengthening structures being subjected to blast effects.