Influência do aditivo plastificante e metacaulim nas propriedades tecnológicas da argamassa de revestimento com vermiculita expandida.

Abstract

are increasingly being sought for these cement composites in order to reduce environmental impacts and meet the requirements of the building performance standard, NBR 15575 (2013), which imposes minimum requirements for mortars. the thermal behavior of buildings. Thus, some materials have been added to mortars in order to provide them with thermal insulation characteristics, which are light aggregates, especially expanded vermiculite. Several studies with this lightweight aggregate show that these mortars consume more water to achieve workability and have low mechanical strength. In contrast, water reducing additives are used to reduce the mixing water of mixtures, and pozzolans (especially metakaolin) are employed to promote higher strength and durability of coatings. Therefore, the aim of this study was to analyze the use of plasticizer additive and metakaolin in the properties of expanded vermiculite mortars. The analyzes of these properties were made in the fresh state (consistency index, fresh mass density and incorporated air content) and hardened (apparent mass density, compressive strength, capillarity water absorption and thermal conductivity). The mixtures were separated into 3 groups, as follows: Group 1 containing only reference cement mortars without light aggregate and varying the plasticizer additive content; Group 2 containing mixtures with 25% expanded vermiculite as a substitute for natural sand, varying the plasticizer additive content and lime ratio and Group 3 was composed of the same mixtures as Group 2 with the addition of 10% metakaolin. It was observed that the replacement of natural sand by 25% of vermiculite caused changes in the properties of the mortar, since its structure interfered with the mass density, incorporated water content, parameters that influence other properties. The plasticizer additive, despite reducing the amount of water in the vermiculite mixtures, did not improve the compressive strength; The vermiculite and metakaolin mortars had the best mechanical strength values and had lower thermal insulation compared to the mortars with only VE, however, they still have better thermal performance than ordinary mortars.