Fiber reinforced wet-mix shotcrete under impact

As a result of excavation blasting, traffic, sudden ground movements, rock bursts, and seismic activity, shotcrete is often subjected to impact and other dynamic loads. Limited data exist, however, with regard to the resistance of shotcrete to such dynamic loads. Impact resistance of wet-mix shotcrete reinforced with 10 different types of fibers was investigated using instrumented drop weight impact tests. A direct comparison was made with the quasi-static response. Both beam and plate specimens were tested and the data were correlated. Fiber reinforcement was found to be highly effective in improving the fracture energy absorption and toughness under impact loading, but the improvements under impact loading were found to be substantially different than those seen in quasi-static tests, and were also highly dependent on the type of fiber used. When beams and plates were compared, the relative improvements between fiber types were found not necessarily in agreement.