Uso de resíduo caulins da amazônia para a produção de precursores geopoliméricos utilizados na indústria da construção civil

Abstract

The region of the Capim River (Northeast of the State of Pará), due to its large reserves of kaolin for covering paper, stands out nationally. The extraction of the ore occurs on average at a depth of 20 meters, covered by clayey-sandy sediments from the barrier formation, and from a level of hard kaolin, also known as flint or semi-flint kaolin(Ferruginous), considered stable depending on the content high iron content, which makes its application for roofing unfeasible. The research aims to address the development of geopolymers synthesized from waste containing aluminum silicate. Geopolymers are amorphous, threedimensional alkalis. Aluminosilicate binder materials synthesized from alkaline activation of clays, calcined clays, calcined kaolin, minerals, industrial waste, fly ash and other aluminosilicates. The fly ash generated in the Bayer process boilers under conditions of 900 °C and 120KPa was also used as a source of aluminosilicate in the geopolymerization reaction. To increase the reactivity of the reaction, the use of soft kaolin and flint and semi-flint(ferruginous) kaolin calcined at different temperatures(450,550,650, 700 and 800 °C) was evaluated. And, also at different calcination times(15,30,60 ,90 and 120 minutes). Sodium hydroxide (NaOH, 5-30 M) and sodium silicate (Na2SiO3, SiO2/Na2O = 3.2) as alkaline reaction medium. The residues were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). And, compressive strength tests were also carried out on the geopolymeric samples to evaluate the degree of polymerization, since the more polymerized the structure is, the greater the resistance. For the geopolymer based on (soft kaolin and fly ash), the best results were obtained for the SiO2/Al2O3 ratio of 2.65 and 3.4. For the geopolymer based on (flint kaolin and fly ash) the best result was for the SiO2/Al2O3 ratio of 2.95 and 3.57. The best results for the geopolymers based on (ferruginous metakaolin and fly ash) were obtained with a SiO2/Al2O3 ratio of 2.88 and 3.54. The geopolymeric ceramic plate obtained showed satisfactory performance in relation to mechanical resistance to compression and was also synthesized with raw material that contaminates the environment, as it is considered kaolin residue due to its high iron content.