Abstract
This study is aimed at finding the contribution of the varied quantities (5, 10, and 15 wt%) of iron filing (IF) on the strength of silica fume (SF) blended ordinary Portland cement (OPC) paste. The paste was developed such that water/(IF + SF + OPC) ratio was maintained as 0.35 at a constant 10 wt% SF content in the binder. The early (7-day) strength was found to be lower than the control (0% IF) due to disruption of hydration process. The decrease in strength of SF blended paste was increasing with the increase in the IF up to 15%. The maximum 28-day compressive strength of 119 MPa was achieved when OPC blended binder was replaced with 5%IF. The maximum strength was reduced by 18.4 and 23.8% as the OPC substitution level increased to 10 and 15% IF, respectively. The presence of IF within the blended paste appeared not to combine chemically with hydration products. This caused nonuniformity in the microstructural texture thereby increasing the carbonation effect in the plain paste. However, the presence of SF in the paste reduced carbonation significantly as reflected in the reduction in the peak of -C-O- vibration as observed through FTIR spectroscopy.