PROPERTIES OF STEEL FIBER-REINFORCED SHOTCRETE

Five commercially available steel fibers with different geometries were investigated both in dry-mix and in wet-mix shotcretes. In the dry process, bulk-bin bags with dry premixes were used. In the wet process, ingredients were wet-mixed centrally in a batching plant and then transported to the shooting site in ready-mix trucks. Mixes were shot on wooden forms and the rebound characteristics of the fibers and other ingredients were determined. Once hardened, shotcrete panels were sawed and cored to obtain beam specimens for flexural toughness tests and cylinders for compression tests. Hardened shotcrete specimens were also tested for boiled absorption and permeable voids. The boiled absorption and permeable voids data indicated that an adequately dense in-place shotcrete was obtained for both processes. The rebound of fibers in the dry process was found to be much higher than that in the wet process. Both compressive and flexural strengths were found to be improved because of the addition of fibers. Fibers also led to a significant enhancement in the toughness of shotcrete.