Avaliação dos agregados de resíduos da construção civil em matriz geopolimérica visando aplicação em pisos intertravados

Abstract

The production of Portland cement (PC) is seen as aggravating the environment, so scientists and engineers look for alternatives to replace this type of binder. Geopolymers have the potential to replace CP, as it aims to reduce CO2 emissions and contributes to high compressive strength. Therefore, this work aimed to prepare concrete from geopolymeric binder obtained with commercial metakaolin and sodium hydroxide (concentration of 12 mol) and pH above 12, respecting the Si/Al ratio equal to 2, which is appropriate for application in interlocking floors. Another point of interest was the evaluation of coarse aggregate from civil construction waste (RCC), especially those from red ceramics compared to conventional coarse aggregate (gravel). Application of civil construction waste in geopolymers is scarce in the literature, requiring a comparative analysis with CP concrete. The methodology consisted of preparing the concrete under the same conditions, that is, curing at room temperature and forming by sleeping pieces. Initially, the determinant characteristics analyzed for application were the compressive strength and water absorption, both at 28 days of curing. The results showed that only the composition of CP with crushed stone met the specifications for the application of interlocking pavements (39MPa), and that the geopolymer matrices are strongly dependent on the degree of crystallinity of the precursor and suitability of the activator, factors that were only confirmed by new compositions. with metakaolin of different Christianity and different activator of the same pH (composed of a mixture of silicate and sodium hydroxide). It was concluded that the previous characterization of the precursor raw material is important, especially regarding its chemical composition and crystallinity. For the development of geopolymer concrete for interlocking pavements, the produced and/or commercial metakaolin used in the matrix were exclusively contributors to the low compressive strength obtained.