Exploring the impact of copper slag on the physicochemical properties of Portland limestone cement (PLC)

Abstract

This study investigated the impact of copper slag on the physicochemical properties of Portland limestone cement (PLC), focusing on the substitution of Fe for Al ions in hydrate phases like AFm and AFt. Addition of copper slag delayed induction period, slowed silicate and aluminate reactions, and reduced total heat release during hydration owing to its low reactivity and small surface area. In PLC paste added with 13.0 wt% copper slag, comparable or higher strength was achieved at all curing days compared to plain PLC paste. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR) spectroscopy showed similar formation of Fe-AFt and Fe-AFm at 28 days. Fe K-edge X-ray near-edge structure (XANES), transmission X-ray microscopy (TXM), and scanning electron microscopy (SEM) confirmed the replacement of Al with Fe ions in the AFt and AFm phases. By conducting mercury intrusion porosimetry (MIP), incorporation of copper slag induced a reduction in large pores (0.06–0.08 μm diameters) and an increase in smaller pores (0.04–0.06 μm diameters) of the PLC paste.