Influence of nano-silica on the microstructural and mechanical properties of high-performance concrete of containing EAF aggregate and processed quarry dust

Abstract

The present study investigates nano-silica (NS) in ternary binder composite and the influence of the same on Electrical Arc Furnace (EAF) slag coarse aggregate-based various high-performance concrete (HPC) mixes. Processed Quarry Dust (PQD) was used as fine aggregate throughout the investigation to limit the consumption of natural river sand and make HPC more sustainable. Control HPC was designed using the Ordinary Portland Cement (OPC)- Ground Granulated Blast Furnace Slag (GGBS) binary binder and various replacement levels of natural crushed granite rock aggregate by EAF coarse aggregate. Additionally, the binary binder composite was added with colloidal nano-silica to achieve high strength HPC. A microstructure study was carried out on paste samples of OPC, OPC with GGBS, and OPC, GGBS with the inclusion of nano-silica. FESEM, EDX, XRD, FTIR, and TGA results showed that the addition of nano-silica has significantly enriched the microstructure characteristics of the binder system. The slump flow of HPC mixes decreased drastically with the inclusion of nano-silica and EAF aggregate. Mechanical properties viz., compressive strength, split tensile strength, flexural strength, and modulus of elasticity of HPC mixes containing EAF and nano-silica have exhibited superior results due to the synergetic effect of nano-silica as well as the more robust physical characteristics of EAF aggregate compared to natural crushed granite rock aggregate. The UPV values and water absorption tests have shown that nano-silica positively affects the binder composite system.