Limestone impact on properties, microstructure and CO2 emissions of waste glass-activated blast furnace slag cements

• Published in: Materials and structures 2024-11, Vol.57 (9), Article 194
• Main Authors: Aragón-Gijón, R. I., Rodríguez-Morales, J., Díaz-Guillén, J. A., Escalante-García, J. I., Burciaga-Díaz, O.
• Format: Article
• Language: English
• Subjects: Activated carbon; Blast furnace practice; Blast furnace slags; Building Materials; Cement; Civil Engineering; Compressive strength; Engineering; Limestone; Machines; Manufacturing; Materials Science; Microstructural analysis; Microstructure; Municipal waste management; NMR; Nuclear magnetic resonance; Original Article; Pastes; Portland cements; Processes; Silica glass; Silicates; Silicon dioxide; Slag; Slag cements; Sodium silicates; Solid Mechanics; Solid waste management; Solid wastes; Theoretical and Applied Mechanics; Thermal analysis
• ISSN: 1359-5997; 1871-6873
• DOI: 10.1617/s11527-024-02469-w

Utilizing industrial and urban solid wastes is crucial for developing low-carbon cements. This study proposes a novel method to integrate recycled glass and blast furnace slag (BFS) into alkali-activated cements. It also investigates the influence of pulverized limestone (LSP), as a readily available cost-efficient partial replacement for BFS. The activators were alternative solid sodium silicates (SSWG), prepared by thermochemical treatment of soda lime silica waste glass in NaOH solutions. SSWG had moduli (Ms) SiO 2 /Na 2 O = 1 and 1.5 and were added at 6 and 8%wt. Na 2 O relative to the mass of BFS + LSP. After 3 years, pastes of 100% BFS at 20 °C yielded the highest compressive strength of 78 MPa, while incorporating 50–75% LSP resulted in 61–42 MPa, depending on the Ms and %Na 2 O. Microstructural analysis via XRD, thermal analysis, SEM, and 27 Al and 29 Si NMR, indicated the formation of cementitious products like C–S–H, C–(A)–S–H, hydrotalcite, natron, gaylussite and pyrssonite. LSP increased the chain length in C–(A)–S–H-type products and affected the Al uptake by a seeding effect. The eco-efficiency analysis showed that the studied cements emit 45–74% less kgCO 2 .eq per ton than Portland cement.