Can tundish deskulling waste be used as a magnesium oxide source to develop magnesium phosphate cement?

Abstract

Ordinary Portland cement (OPC) has a significant environmental impact since approximately 0.81 kg of CO2 is generated for every kilogram produced. Thus, it is mandatory to look for sustainable alternative cements. One of the most promising materials in this sense is magnesium phosphate cement (MPC). This study evaluates the possibility of revaluing a waste obtained from the tundish deskulling (TUN) as a raw material for formulating alternative MPC. This approach aims to promote the circular economy and minimizing the environmental impact of MPC. The tundish working lining is a crucial refractory material used in continuous steel casting. An optimal cement formulation was achieved by maximizing the compressive strength (CS) at 7 days, resulting in the combination of 60 wt% of TUN and 40 wt% of KH2PO4, with a water/cement (W/C) ratio of 0.27. The physical and mechanical properties were evaluated at three different stages: after 1, 7, and 28 days of curing. Furthermore, an exhaustive physicochemical characterization was conducted to investigate the feasibility of using it as an alternative cement. This study confirms the feasibility of formulating MPC using TUN as raw material due to the main product obtained, which is K-struvite. The use of TUN implies important economic savings and enhances sustainability criteria avoiding its management in landfills.