Since the early 1970s, steel fiber reinforced shotcrete has been increasingly used for such applications as support in tunnels, mines, excavations, and rock slopes. Previous studies have shown that steel fiber reinforced shotcrete, at fiber addition rates now commonly used, can provide equivalent or even superior performance than that provided by standard wire mesh reinforcement, when properties such as residual load-carrying capacity after first crack are compared. This paper presents the results of recent studies comparing the performance of common wire mesh reinforced shotcretes with that of shotcretes reinforced with high-volume concentrations of a collated fibrillated polypropylene (CFP) fiber. The tests were conducted using wet-mix shotcrete applied to large panels, which were anchored and loaded to destruction with continuous monitoring of the crack formation and load vs. Deflection characteristics of the panels. The panels were tested in the same manner as tests previously conducted on plain, wire mesh, and steel fiber reinforced shotcretes. Thus, the performance characteristics of the various shotcrete mixtures can be compared. It is shown that at certain addition rates of CFP fiber, similar residual load-carrying capacity after first crack can be obtained compared with shotcrete reinforced with wire mesh and shotcrete reinforced with steel fiber. Testing of standard flexural test beams to ASTM c1018 provided further verification of the equivalence of performance between shotcretes with these levels of addition of steel and CFP fiber with respect to parameters such as toughness index. The incorporation of high-volume concentrations of CFP fiber in wet-mix shotcrete presents opportunities for a wide range of applications where a tough, ductile, corrosion-resistant material is required.
Samenvatting