Strength, permeability and microstructure of self-compacting concrete with the dual use of ferronickel slag as fine aggregate and supplementary binder

The study herein addresses the scope to maximize the combined use of by-product ferronickel slag (FNS) as a fine aggregate and ground FNS (GFNS) as a supplementary binder to enhance the sustainability of self-compacting concrete (SCC). The development of strength, permeability and microstructures of SCC containing up to 50% supplementary binder and 50% FNS fine aggregate were investigated. It was found that the fresh properties of concrete incorporating FNS and GFNS remained well within the recommended limits of the European standard for SCC. The 28 days compressive strength of high strength SCC using FNS and GFNS varied within 10% of that using natural sand and fly ash as an SCM. Splitting tensile strength and elastic modulus could be predicted by the standard equations used for conventional vibrated concrete. Tests such as volume of permeable voids, water absorption, sorptivity and water penetration showed good physical properties of SCC incorporating FNS and GFNS. Investigation by SEM and EDS showed a compact microstructure by the reaction product of GFNS which is similar to that produced by pozzolanic reaction of fly ash. Overall, up to 30% cement replacement by GFNS and 50% sand replacement by FNS was found feasible for the production of SCC of high strength and good physical properties indicating high durability.