Strength and Wear Resistance of Sand-Replaced Silica Fume Concrete

Abstract

This investigation evaluates: 1) the influence of silica fume content on the strength and resistance to wear of 3-, 7-, 28-, and 91-day moist-cured concretes made with 0, 5, 10, 15, and 20% silica fume replacing a portion of the fine-aggregate; and 2) the influence of various combinations of curing schemes on the strength and resistance to abrasion of the selected fine aggregate-replaced silica fume concretes. A uniform cement factor of 385 kg/m 3 (650 ld/yd 3 ) and a constant water-cementitious material ratio (w/cm) of 0.325 are used in all trial mixtures. The fresh and bulk characteristics, such as slump, air content, time of setting, bleeding, unit weight, and compressive strength are obtained to characterize the selected matrixes. ASTM C 779, Procedure C, Ball Bearings, is used to evaluate the resistance to wear. The compressive strength and abrasion resistance of the fine aggregate-replaced silica fume concretes cured under a continuous moist-curing condition and various combinations of wet-dry curing cycles are compared. The relationships among depth of wear, compressive strength, percentage of silica fume content, and curing age are also studied. Laboratory test results conclude that both the compressive strength and resistance to wear peaked at 10% silica fume content. Silica fume incorporation in concrete by way of fine aggregate replacement did not alter the samples' compressive strength when subjected to the various combinations of wet-dry curing cycles. When compared with continuous moist curing, the selected cycled wet-dry curing conditions caused a modest reduction in resistance to abrasion that varied with silica fume contents, curing cycles, and curing schedules. There was statistically a significant correlation between the dependent variable (depth of wear) and the independent variables (compressive strength, percentage of silica fume content, and curing age) for the samples aged under continuous moist-curing conditions.