Sustainable use of ferronickel slag in cementitious composites and the effect on chloride penetration resistance

Sufficient utilizations of ferronickel slag (FNS), an industrial waste discharged from nickel smelting and stainless-steel production process, are essential under the background of sustainability development. In this work, the replacement of ordinary Portland cement by FNS and its influence on chloride penetration are systematically investigated. A range of measurements including RCPT, corrosion current, natural diffusion, pore structure and X-ray diffraction was carried out. The results show that the concrete pore structure can be refined with an appropriate dosage (up to 30%) of FNS, whereby a higher resistance to reinforcement corrosion and a reduction of electrical conductivity are found. With the inclusion of FNS the chloride binding capacity of cement pastes is enhanced and the binding behavior can be expressed by the Langmuir isotherm. The addition of FNS leads to a higher amount of amorphous C-S-H phases. The formation of hydrotalcite-like phases and the higher C-S-H content account for the enhanced chloride binding of FNS pastes. (C) 2019 Elsevier Ltd. All rights reserved.