Toward circular economy: In-situ zeolitic mineral wool waste/slag-based geopolymers for sustainable construction and wastewater remediation

This study highlights an innovative approach to valorize rock wool and glass wool wastes (RWW and GWW) via incorporating them into a slag-based geopolymer to prepare low-carbon construction materials and adsorbent agents for indigo-carmine dye. The slag was partially replaced with 50 wt% RWW (Geo-R) or GWW (Geo-G), then cured under two curing regimes: normal-curing/28-days and hydrothermal-curing/150°C/12hrs. The effects of curing regime and precursor type on mechanical and adsorption properties were investigated. The results showed that hydrothermal curing significantly enhances geopolymer properties, yielding higher compressive-strength and improved adsorption efficiency compared with normal curing. The highest strength (47 MPa) and the highest removal efficiency (93%) were achieved by hydrothermal-cured Geo-R and Geo-G, respectively. These data were approved by XRD, FTIR, BET/BJH and SEM/EDX analyses. The Ca/Mg/Al-rich Geo-R promoted the formation of load-bearing capacity phases from C-(A)-S-H, hydrotalcite and gismondine-Ca. The Na/Si-rich Geo-G developed highly-adsorbent LTA, sodalite and ZSM-5 mesoporous structure zeolite.