Mechanochemical activation of waste glass in alkaline composite cements with blastfurnace slag: A sustainable approach to recycling

This study investigates alkali-activated cements incorporating blast furnace slag and urban waste glass across varying slag:glass ratios (100:0, 25:75, 75:25, 0:100). Activation with 4 % and 12%Na(2)Oeq, coupled with two curing regimes (24h at 60 degrees C, followed by either 60 degrees C or 20 degrees C for 28 days), was explored. Prior to each formulation, part of the waste glass underwent mechanochemical ball milling with the required water and alkalis, to enhance the glass reactivity and to pre-dissolve SiO2 and other species to obtain a waterglass-like material in an environmentally friendly manner. Optimal strengths were achieved for slag binders (27 MPa) with 4%Na2O and 20 degrees C curing, while waste glass binders (48 MPa) required 12%Na2O and 60 degrees C. Composite formed cementitious products of CaO-(Al2O3)-SiO2-H2O gel, calcite, and hydrotalcite as reaction products, while 100 % waste glass binders displayed cementitious products of CaO-SiO2-H2O intermixed with silica gel. This approach holds promise for reducing environmental impact and promoting the efficient widespread and straightforward reuse of urban waste glass in construction materials.