Evaluation of the long-term compressive strength development of the sewage sludge ash/metakaolin-based geopolymer

• Autores: D. Istuque, L. Soriano, María Victoria Borrachero Rosado, Jordi Payá Bernabeu, J. L. Akasaki, J.L.P. Melges, M. M. Tashima
• Localización: Materiales de construcción, ISSN 0465-2746, Vol. 71, Nº. 343, 2021
• Idioma: inglés
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• Resumen

  • This paper aimed to evaluate the long-term compressive strength development of the sewage sludge ash/metakaolin (SSA/MK)-based geopolymer. SSA/MK-based geopolymeric mortars and pastes were produced at 25ºC with different SSA contents (0 - 30 wt.%). Compressive strength tests were run within the 3-720 curing days range. A physicochemical characterisation (X-ray diffraction and scanning electron microscopy) was performed in geopolymeric pastes. All the geopolymeric mortars presented a compressive strength gain with curing time. The mortars with all the SSA evaluated contents (10, 20, 30 wt.%) developed a compressive strength over 40 MPa after 720 curing days at 25ºC. The maximum compressive strength of the mortars with SSA was approximately 61 MPa (10 wt.% of SSA), similarly to the reference mortar (100% MK-based geopolymer). The microstructure analyses showed that the SSA/MK-based geopolymer presented a dense microstructure with N-A-S-H gel formation.