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

Abstract

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.

Polyurea for Blast and Impact Protection: A Review

“…It was also found that polyurea can hardly improve the static load carrying capacity of reinforced concrete arches in the study by Liu et al [40]. Notably, in the study by Sonoda et al [114], they revealed that the polyurea protective coating is also not effective against RC structures for the first impact loading action at low and medium strain rates. With repeated impacts, however, the improvement of polyurea on the impact resistance of RC structures is significant and can significantly inhibit structural cracking and rigidity loss [114].…”

“…Notably, in the study by Sonoda et al [114], they revealed that the polyurea protective coating is also not effective against RC structures for the first impact loading action at low and medium strain rates. With repeated impacts, however, the improvement of polyurea on the impact resistance of RC structures is significant and can significantly inhibit structural cracking and rigidity loss [114]. Among the many researchers studying the polyurea enhancement of concrete structures against blast and impact loads, the polyurea inhibition of structural crack evolution and spalling is considered an important macroscopic level of protection.…”