THERMAL AND MECHANICAL ANALISYS OF COATING MORTARS WITH ADDITION OF EXPANDED VERMICULITE INSTEAD OF AGGREGATE
thermal performance, lightweight mortar, thermal mortar, performance standard.
The search for building materials that lead to advances, especially as regards to the aspect of energy efficiency of buildings, is increasingly constant nowadays. In Brazil, the Performance Standard (ABNT NBR 15575: 2013) establishes the minimum standards about the efficiency of buildings in the country, bringing among criteria of structural stability and useful life, the guidelines to obtain thermal and acoustic comfort, and fire safety. In this context, there is a growing number of studies aiming to investigate the use of lightweight aggregates, such as expanded vermiculite, which has important properties, specifically low thermal conductivity and high fire resistance. Thus, the current research sought to evaluate the thermal performance of mortars in the 1: 1: 6 volume, with the addition of expanded vermiculite (superfine) in defined percentages of replacement to the small aggregate (25%, 50%, 75%, and 100%). The experimental procedure was initiated with the chemical, mineralogical, microstructural and thermal characterization of the expanded vermiculite, and with its physical characterization and with the constituent sand. The analysis of the properties of workability, water retention, retraction, capillary absorption, and mechanical strength of each mixture was performed. In order to determine the energy efficiency of the coating, thermal characterization tests of the mortar were carried out using the KD-2 Pro and a prototype. In the results of the fresh and hardened state, it was observed that the mortars containing expanded vermiculite presented higher water consumption, lower mass density, higher water retention capacity, reduction of mechanical strength and modulus of elasticity, and increased capillary absorption and index of voids. In the analysis of the thermal performance, it was observed that, in ceramic brick sealing systems, whatever the mortars used and the bioclimatic zone chosen, all meet the thermal transmittance requirements required by NBR 15575: 2013, and only the mortar with 100% of vermiculite does not meet the established limit of thermal capacity. In the concrete block fence system, only 75% and 100% replacement mortars contribute with all the thermal transmittance requirements required for the system. However for the thermal capacity limits, all are considered adequate. The good thermal performance was also confirmed in the experiment with the prototype, when the heat reduction propagation from one environment to the other with the addition of vermiculite in the mixture. Thus, it is indicated that the addition of expanded vermiculite in mortars results in coatings with good thermal performance, which can meet, according to the situation, the requirements established by the ABNT NBR 15575:2013.