Síntese e caracterização de geopolímeros a partir da utilização de resíduos industriais

Abstract

With a growing in environmental discutions, there is a need to minimize CO2 coming from the cement industries, at the same time develop similar products in order to reduce these impacts. Geopolymers are developed from aluminosilicate precursor materials activated in a highly alkaline system through the geopolymerization process. The objective of this work was to evaluate the potential use of mineral coal and glass residues in the development of geopolymeric masses. The mixtures developed were composed of four distinct traits. The activator solution is composed of sodium hydroxide (NaOH) dissolved in 10M, 12M and 14M and alkaline sodium silicate (Na2SiO3) in the ratio 1:2. The liquid/solid ratios were fixed at 0,4; 0,6 and 0,8. The masses produced were kept in thermal curing at 65°C for the first 24 hours, after that, they were kept in an airconditioned chamber for up to 28 days of curing. The tests performed on the synthesized products were compressive strength tests, scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetry.The trace containing 25% coal residue and 75% glass residue presented better compressive strength as the liquid / solid ratio decreased, reaching 23,34 MPa for l/s 0,4 with a concentration of 12M. The scanning electron microscopy analyzes indicated the presence of the aluminosilicate gel N-A-S-H composed of Na, Si and Al and the C-A-S-H gel coming mainly from the increase of Ca present without precursor. Traces with the highest amount of RC presented loose particles that did not react at the time of geopolymerization leaving a weak or poorly bound structure. At traces with a higher proportion of carbon residue, as the X-ray diffraction (XRD) analysis indicated that the products formed are in an intermediate state between the amorphous and semi-crystalline states. The XRD analysis of samples containing glass in its greatest proportion indicated the presence of gismondin, characteristic of the formation of hydrated aluminosilicates from geopolymerization. In the thermogravimetry analysis, mass loss events were observed, all of them below 5%, due to dehydroxylation of hydrated aluminosilicate gels formed during geopolymerization.Therefore, carbon and glass residues have the potential to be used in geopolymer matrices, enabling applications such as subfloors, sidewalks, concrete blocks, foundations, among others.