Propriedades de compósitos à base de gesso com diferentes resíduos para proteção térmica em edificações

Abstract

Gypsum is a cementitious material with a lower environmental impact than other binders such as cement or even lime. In civil construction it has been used in decorative pieces, lining boards, blocks for walls and now also as mortar. By hardening, gypsum, unlike Portland cement, forms a matrix of almost neutral pH, which means that it can incorporate fibrous materials of plant or animal origin without degrading them. The recent norms concernig performance of the buildings give much prominence to the thermal behavior of walls and roofs. The gypsum can serve as a matrix to incorporate materials that promote the reduction of its thermal conductivity, among them different residues generated by human activities. This work continues the researches that have been developed at the UFPB that seek to create new uses and to diffuse gypsum as a cementitious material with greater application in the civil construction. One of the contributing factors is the plasticizer admixtures developed in other dissertations that allow water reduction, increase of resistance and time of hardening. In this dissertation the thermal and mechanical properties of gypsum composites were established so that different constructive elements could be developed. Five residues were used: Kraft paper, plain paper, Ethylene Vinyl Acetyl (EVA) powder, EPS, and the leather footwear industry. For each of these residues three different amount were tested. The set time, density, ultrasonic wave propagation velocity and modulus of elasticity, compressive strength and flexural strength of the different composites were investigated. The compositions with the lowest values of ultrasonic wave propagation velocity and density were selected for thermal conductivity test. The results showed that the sisal additive influences the performance of the material, mainly in relation to the flexural strength. They also indicated that the best composite was formed with EVA powder as reinforcement phase, because this composite presented lower ultrasonic wave propagation velocity, lower specific mass, lower thermal conductivity and better flexural strength when it was used with the additive of sisal. However, the other composites also have lower thermal conductivity than the gypsum matrix, so they can be used for the production of thermal protection plates for the constructions in general.