Synthesis of an Alternative Hydraulic Binder by Alkali Activation of a Slag from Lead and Zinc Processing

• Published in: Waste and biomass valorization 2020, Vol.11 (1), p.375-388
• Main Authors: Millán-Corrales, G., Magallanes-Rivera, R. X., González-López, J. R., Zaldivar-Cadena, A. A., Figueroa-Torres, M. Z.
• Format: Article
• Language: English
• Subjects: Activation; Aging; Civil engineering; Compressive strength; Construction materials; Engineering; Environment; Environmental Engineering/Biotechnology; Gels; Heat treatment; Hydration; Industrial Pollution Prevention; Lead; Mechanical properties; Metallurgical analysis; Original Paper; Pastes; Reaction products; Renewable and Green Energy; Setting (hardening); Silicon dioxide; Slag; Sodium hydroxide; Sodium silicates; Viability; Waste Management/Waste Technology; Zinc
• ISSN: 1877-2641; 1877-265X
• DOI: 10.1007/s12649-018-0363-1

The feasibility of use of a latent reactive waste from metallurgical processing to produce usable construction materials was studied. Hydraulic pastes were obtained by alkaline activation of a slag from lead and zinc concentrates. Their mechanical properties were measured and characterization performed to determine the viability of stable binder formation and the nature of the resulting reaction products after slag hydration. Water glass (Na 2 SiO 3 ) was used as the main activator of the slag; the SiO 2 /Na 2 O ratio was modified by inclusion of NaOH. The results showed that alkaline activation of the slag was viable, resulting in setting and hardening of the pastes via hydration reactions. The pastes developed compressive strength above 50 MPa after curing for 120 days in humid environment, being potentially useful to produce consolidated materials for structural applications in civil engineering, as a consequence of the formation and structuration of reaction products of C–(N)–A–S–H type embedded in a dense matrix of intermixed C–S–H and N–A–S–H gels. Encapsulation of trace metallic lead in the slag by embedment in hydrated phases was observed in the microstructure of the pastes. No improvement in strength was observed on further aging after initial thermal treatment of pastes at 80 °C.