Reinforcing effect of polyurea resin coating on RC members subject to low-speed and medium-speed impact

Polyurea resin is widely used as a coating material for various structures owing to its relatively high strength and elongation ability along with applicability in improving the impact and explosion resistance of structures has been studied. Civil engineering structures are generally subjected to relatively low-speed impact loads, such as collisions with vehicles, falling rocks, and flying objects caused by typhoons. However, the reinforcing effect of polyurea resin against low-speed impact loads has not been well studied. The objective of this study is to understand the reinforcing effect of polyurea resin coating on RC members against low-speed and medium-speed impact loads and to evaluate its effectiveness. We conducted low-speed and medium-speed repeated impact tests using a falling weight and flying object on RC cantilevers and slabs coated with polyurea resin, respectively. In addition, numerical simulations were performed using the FEM to qualitatively reproduce the experiments. The results of the low-speed impact test showed that there was no significant reinforcing effect under the first impact. However, when the number of impacts increased, the maximum displacement was significantly suppressed; thus, the improvement of the impact absorption performance was confirmed. In addition, by coating the back side of the RC slab, the prevention of the scattering of concrete pieces was verified in the medium-speed repeated impact test.