Recycling analcime residues of lithium production from spodumene ore in eco-friendly cementitious binders

Abstract

There is an increasing need for supplementary cementitious materials (SCMs) to ensure the sustainability of concrete production. This study investigates the potential of using analcime-rich material, a byproduct of lithium refining from spodumene, as a means of reducing clinker content in concrete while also finding a suitable application for this type of industrial residue. The production of analcime residue is expected to rise in the future due to the green transition and the increasing demand for batteries. Cement was substituted with analcime residue at 10, 15, 20, and 30 wt.% in the preparation of pastes and mortars. These mixtures were characterized for their fresh and hardened state properties using isothermal calorimetry, rheology, setting time analysis, compressive strength testing, X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). The Rapid, Reliable, Relevant (R³) test revealed that analcime residue exhibited a cumulative heat release of 278 J/g and bound water content of 5.4 g per 100 g of residue, indicating moderate reactivity. SEM-EDS analysis further confirmed the reactivity of the analcime residue. The substitution of cement with 10 wt.% analcime residue resulted in mortars with comparable rheological and mechanical properties to the reference sample, achieving compressive strengths of 45 MPa at 28 days and 57 MPa at 90 days. Although strength decreased with increasing analcime residue content, samples prepared with 30 wt.% substitution still exhibited a strength activity index exceeding 75% at 28 days, demonstrating its potential as a partial clinker replacement in sustainable concrete production.