Mechanical Behavior of Hardened Concrete with Variation Silica Fume and the Water Cement Ratio w/c

This research examines the combined effect of silica fume (SF) percentage and water-cement (w/c) ratio on the performance of hardened concrete. The experiment used eight concrete mixes consisting of SF percentage of 0%, 7%, 13%, and 18% at two ratios of w/c: 0.4 and 0.5. The mechanical performance of each mix was determined in terms of compressive strength, tensile strength, and density after curing. It is found that the inclusion of silica fume improves the performance of concrete mix until its maximum content of 13%. At 13% content of SF and w/c ratio of 0.4, maximum compressive strength (24.85 MPa) and tensile strength (4.0 MPa) can be obtained owing to its contribution to enhanced microstructure through pozzolanic reaction and filler action. However, increase in w/c ratio to 0.5 reduces the strength values due to increased porosity. The ANOVA test showed that both SF percentage and w/c ratio have significant effect on mechanical performance (p<0.01), but the latter is a more influential parameter.