Title: A Comparative Evaluation of Plain, Mesh and Steel Fiber Reinforced Concrete
Author(s): Dudley R. Morgan and Dallas N. Mowat
Publication: Symposium Paper
Appears on pages(s): 307-324
Keywords: compressive strength; evaluation; flexural strength;
impact strength; metal fibers; shotcrete; welded wire fabric.
Plain and mesh reinforced shotcrete have been used for many years for ground support in tunnels, mines, excavations and rock slopes. Since the early 1970's steel fiber shotcrete has enjoyed increasing use in such applications. The question has often been asked how steel fiber reinforced shotcrete performs under loading in such applications compared to plain and mesh reinforced shotcrete. There is a dearth of published literature on this subject and this study seeks to help fill this void. In this study, 1.52 m x 1.52 m x 64 mm (5 ft. x 5 ft. x 21/2 in.) shotcrete panels were fabricated using plain shotcrete, plain shotcrete reinforced with 2 in. x 2 in. x 12/12 wire mesh, and shotcrete with two concentrations of steel fiber. The panels were anchored at 1.22 m (4 ft.) centers with two different conditions of restraint and loaded to destruction with continuous monitoring of the load versus deflection and fracture characteristics of the panels. Under the conditions of test, the improved residual load carrying capacity of the mesh and steel fiber reinforced shotcrete after first cracking, compared to the plain shotcrete, was well demonstrated. The steel fiber reinforced shotcrete panels also displayed improved residual load carrying capacity after first crack compared to the mesh reinforced shotcrete at deformations up to 10 mm (1/2 in.), and equivalent residual load carrying capacity at deformations up to 50 mm (2 in.). The inherent toughness and ductility characteristics of the steel fiber reinforced shotcrete were enhanced by increasing the volume concentration of steel fiber from 0.75 percent to 1.25 percent by volume.