Estudo das propriedades reológicas e térmicas das argamassas de revestimento contendo adições minerais e vermiculita

Abstract

The construction industry has increasingly sought to modernize as well as meet the requirements with regard to environmental impact. In the last 5 years, it has also been adapting to meet the minimum requirements of the building performance standard (NBR 15.575, 2013). Among the various requirements of this standard, we highlight that referring to the thermal behavior of the building. Different materials and construction solutions have been used to improve this thermal performance. Among the existing solutions in the market can be highlighted the use of mortars with thermal insulation property, which can promote both environmental and economic gain by reducing the use of equipment for cooling the environment. And one of the most commonly used materials for these mortars is vermiculite. Several studies involving the use of vermiculite in coating mortars have been developed, however, its use in conventional coating mortars has resulted in a material with unsatisfactory workability in João Pessoa. Based on this, this study has as its main focus to evaluate the behavior of rheology of mortar with vermiculite in its fresh, hardened state, as well as its thermal conductivity. So for this work the materials were characterized as their physical properties (unit mass, specific mass and particle size), chemical (x-ray fluorescence) and mineralogical (x-ray diffraction) properties. Mortar mixtures containing Portland cement, hydrated lime type CH I, vermiculite, river sand and additions of metakaolin (MC) or ceramic brick residue (RTM), in the ratio of 1: 1: 6, by volume, were evaluated. The sand was partially replaced by vermiculite in the proportions of 40%, 60% and 80%, while the pozzolan additions were added in the proportion of 10% and 20% in relation to the cement mass, and the water content was determined as a function. of the scattering obtained on the table flow. For the fresh state mass density and workability were evaluated by the Squeeze flow method. In the hardened state, mechanical strength, capillary water absorption, mass density, adhesion and thermal performance were evaluated. The results showed that although the mortars had the same consistency index, they showed a distinct behavior in the Squeeze flow analysis, because the vermiculite lamellar structure and the high water content in the mortars that contained it produced a mixture with lower viscosity. The use of vermiculite decreased the mechanical performance of the mortar, but not to the extent that it could not be used as an external coating, and resulted in mortars with up to 77.6% decrease in thermal conductivity compared to the reference mortar.