Mechanical properties and microstructure of steel/iron slag blended mortar

This study aims to examine the mechanical properties and microstructures of steel/iron slag blended mortar (SISBM), which contains two by-products of the steel and iron industries: steel slag (basic oxygen furnace slag, BOFS) and iron slag (blast furnace slag, BFS). Test results indicate that steel slag will have effective hydration reactions with iron slag and contribute strength. The optimal mixing ratio of steel to iron slags was 3:7 (by weight), and the compressive strength was about 83.59% compared with that of ordinary Portland cement mortar (OPM). The strength development was similar to that of OPM and the strength increased as the curing period increased. The X-ray diffraction analysis results implied that the main products of hydration could be C-S-H, C-A-S-H, CaO-MgO-Al2O3-SiO2, Fe0.974O, and C(4)AF. The scanning electron microscope images indicated that the distribution of Ca(OH)(2) and CaCO3 increased as the inclusion of steel slag increased, perhaps resulting from insufficient reactions between BFS and Ca(OH)(2) and f-CaO due to excessive BOFS. In addition, the results indicated that the density of OPM was superior to that of SISBM. This may be the reason for lower strength of SISBM compared to OPM.