Performance as for watertightness of rendering mortars using admixtures

Moisture problems when they arise in buildings, always bring discomfort, and degrade the building over time. It is worth mentioning that the Brazilian technical standard for the performance of residential buildings, presents the requirement of watertightness, in external vertical sealing systems. However, this standard does not specify mortar renderings in terms of watertightness. The standard that classifies mortar renderings recommends the determination of water absorption by capillarity and capillarity coefficient but does not include parameters for use in projects. In 2020, the Brazilian Association of Technical Standards published a technical standard selecting three main admixtures used in inorganic mortars, identified as water-reducing admixtures, air-entraining admixtures and auxiliary adhesion and flexibility polymers. Thus, it appears that the national standards for constructive performance, the standard for mortar renderings and the standard for mortar admixtures no correlation is proposed in that context, thus directing the sealing and renderings systems in isolation. Thus, the main objective of this work is to search for mortar dosages that have low water permeability in rendering systems. The adopted methodology used admixtures air-entraining admixtures, waterproofing admixtures, and hydration stabilizing admixture in the renderings mortars, correlating them to the capillarity coefficients of each mortar produced with the different admixtures. The results showed that the admixtures, of different chemical bases, commercialized for use in the production of mortars, influence the performance of the renderings when subjected to water absorption. In this context, it appears that Brazilian technical standards need correlation between them to ensure the durability of buildings.