Immobilization of Hazardous Wastes on One-Part Blast Furnace Slag-Based Geopolymers


The immobilization of hazardous wastes in ordinary Portland cement (OPC)-based materials has been widely studied and implemented. OPC-based materials have a high carbon footprint associated with their production and geopolymer materials are a sustainable and eco-friendly alternative. Therefore, this work aimed to immobilize two hazardous industrial wastes: copper wastewater sludge and phosphogypsum in one-part geopolymer materials. For that purpose, the precursor was partially substituted by these wastes (5, 10 and 20 wt.%) in the formulations. The geopolymer fresh and hardened state properties were evaluated, and the immobilisation of pollutants was determined through leaching tests. In phosphogypsum pastes (PG5, PG10 and PG20) it was observed that the compressive strength decreased with the increase in its amount, varying between 67 MPa and 19 MPa. In copper sludge pastes, the compressive strength of the specimens (CWS5 and CWS10) reached ~50 MPa. The mortars, MPG10 and MCWSs10, had compressive strengths of 13 MPa and 21 MPa, respectively. Leaching tests showed that pastes and mortars immobilise the hazardous species of the wastes, except for As from copper sludge, whose the best result was found in the compact paste (CWSs10) that leached 2 mg/kg of As. Results suggest that optimized compositions are suitable for the construction sector.



subject category

Green & Sustainable Science & Technology; Environmental Sciences; Environmental Studies


Paz-Gomez, DC; Vilarinho, IS; Perez-Moreno, SM; Carvalheiras, J; Guerrero, JL; Novais, RM; Seabra, MP; Rios, G; Bolivar, JP; Labrincha, JA

our authors


This research was funded by Ministerio de Ciencia e Innovacion (MICINN), grant number PID2020-116461RB-C21 and Agencia de Innovacion y Desarrollo de Andalucia (IDEA) grant number UHU-1255876. This work was done in the scope of the project CICECO- Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, co-financed by national funds through the FCT/MEC. This research was funded by FCT (Portuguese Foundation for Science and Technology), grant number 2020.01135.CEECIND (R.M.N.) and SFRH/BD/144562/2019 (J.C.).

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