APPLICATION OF SILICA FUME IN SYNTHETIC FIBER-REINFORCED CONCRETE

The effect of silica fume on the properties of synthetic fiber-reinforced concrete was assessed. Two fiber types were used: fibrillated polypropylene fibers and polyethylene-terphalate polyester fibers. Various fiber volume fractions were examined. Fiber volumes ranged from 0 to 0.6%, and fiber length was 12 mm (1/2 in.). Silica fume was used as partial replacement of portland cement on an equal-mass basis at 0, 5, 10, and 25%. The fresh mixtures were tested for slump, inverted slump cone time, and air content. The hardened concrete material was tested for compressive and flexural behaviors as well as impact resistance. Rapid chloride permeability was also measured. The purpose of the experimental investigation was to assess the suitability of synthetic-fiber silica-fume concrete for application in bridge-deck overlays and other applications for which the mechanical properties and permeability are important. The results indicate that silica fume is useful in improving the effectiveness of fiber reinforcement of concrete and reducing its permeability.