Estudo da influência da substituição parcial do cimento por resíduo de cerâmica vermelha na transferência de calor em placas de fibrocimento

Abstract

The thermal performance of a building is strongly associated with the properties of the component materials of its wrap. The use of fiber cement boards used in Light Steel Framing (LSF), Light Wood Frame (LWF) systems and ventilated façades has been prominent among the new constructive elements. It is believed that the increase of the thermal resistance of the constructive components for the use of vertical closures contributes significantly to the improvement of the thermal comfort, as well as to the reduction of the energy consumption of the buildings. The use of solid waste from the red ceramic industry (RCV) can be seen as a good option due to its low thermal conduction properties. This work had as objective to evaluate the influence of the partial replacement of the Portland cement by RCV in the heat transference in fiber cement boards. The RCV was from the block and tile manufacturing industry, located in the Southeast region of the state of Paraná. The behavior of two reference structures was evaluated using for one of them CP V ARI cement and the other CP II - F 32. The addition of the limestone and cellulose and polypropylene (PP) fibers as reinforcement was maintained throughout the mixtures, replacing the cement by ground RCV in percentages of 0%, 15%, 25% and 50%. The RCV was characterized by the analysis of water absorption, specific mass, chemical and mineralogical composition. The samples were molded by means of adaptations of the industrial process widely used in the manufacture of boards and tiles in fiber cement for laboratory production, and which have already been used by other researchers. The physical and mechanical performance of the fiber cement boards was also evaluated by analyzing properties such as water absorption, density, porosity and flexural strength, considered important characteristics in the use of the material as a constructive component. In order to report the microstructural properties, x-ray diffraction (XRD) and scanning electron microscope (SEM) tests were performed. The thermal properties of the samples were analyzed using thermal conductivity and thermal delay data in tests performed with samples at 28 days of hydration. The results of mechanical resistance to bending of all the analyzed plates indicated that the use of the ground red ceramic residue obtained a satisfactory result, according to the norm NBR 15498: 2016 - fiber cement boards. The samples showed a drop in the values of density and increase in the porosity, contributing with the positive results achieved in the thermal performance. The partial substitution of portland cement at 25% and 50% RCV contents can reduce the coefficient of thermal conductivity of the boards in relation to the reference samples (0% of RCV) and in relation to commercial boards analyzed. Thus, showing the contribution of the RCV in the thermal performance of constructive components applied in systems of external vertical seals (SVVE), without significantly affecting the mechanical resistance to the flexion of the boards.