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Preparation, characterization, and environmental impact analysis of natural Ecuadorian zeolite tuff-based silicoaluminophosphate geopolymer

Abstract:

Geopolymer cement, especially silicoaluminophosphate (SAP) geopolymer, is a sustainable binder that exhibits unique properties and has the potential to decrease carbon emissions in the construction industry. The SAP geopolymer was prepared using Ecuadorian zeolite tuff and phosphoric acid. Various experiments were conducted to determine the effects of several experimental factors, including phosphoric acid concentration, temperature, and acid-to-zeolite ratio, on the compressive strength of the SAP geopolymers. The results revealed that the SAP geopolymer with the highest compressive strength, GPA-R3, reached approximately 5 MPa after 14 days of aging. Characterization of the geopolymer samples, including X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis, revealed microcracks and pores in the materials, which correlated with the obtained values of compressive strength. A life cycle assessment showed a low environmental impact of geopolymers, particularly when using low acid concentrations. The GPA-R3 sample, which exhibited the best compressive strength, had a promising global warming potential of 535 kg of CO<inf>2</inf>-eq, outperforming other geopolymer and cement alternatives.