Alternativa de síntese de geopolímeros a partir de lama de estação de tratamento de água e cinza de carvão mineral

Abstract

The production of Portland cement is one of the most CO 2 -intensive industrial activities, significantly contributing to climate change. Additionally, the cement manufacturing process consumes large amounts of energy and natural resources. In this context, there is a growing need for more sustainable alternatives for the construction industry. Geopolymers, low environment impact cementitious materials, present a promising solution. This work aims to investigate the production and characterization of geopolymers from residual raw materials, such as water treatment plant slugde (LETA) and coal fly ash. The chemical activation of these precursors was carried out using an alkaline solution composed of NaOH and sodium silicate (Na 2 SO 3 ). Variations in the NaOH concentration (8M and 10M), sludge calcination temperature (uncalcined, calcined at 700 o C and 800 o C), and precursor composition (0%,20 and 40% ash) were tested. The physical and mechanical properties of the produced geopolymers were evaluated, including water absorption, density, porosity, flexural strength, and compressive strength. The formulation that showed the best results was obtained with 10M NaOH, slugde calcined at 700 o C, without ash substitution, reaching a compressive strength of 12.63MPa after 28 days of curing. Additionally, geopolymer and Portland cement speciments were subjected to high temperatures (300 and 800 o C), where the geopolymers demonstrated excellent performance (16 MPa). While Portland cement specimens experienced a 48% reduction in strength after heating, the geopolymers, on the other hand, exhibited a remarkable 28% increase in strength, highlighting their superiority in high- temperature environments.