Formulações de argamassas autonivelantes para contrapiso com incorporação parcial de agregado reciclado de concreto

Abstract

Self-leveling mortar is a material with advantageous characteristics for the industry of civil construction, among them: high flatness, low thickness of the elements that use it, rapid application and short demand of labor for its execution. In order to add knowledge about this material, as well as to make it more sustainable, by incorporating recycled concrete aggregates in its mixture, the present work was proposed. The main objective was to build self-leveling mortars with incorporation of these residues and to characterize them in the fresh state, verifying the technical feasibility of their use. Furthermore, in a complementary manner, it was observed how different combinations of additives may influence the properties of these mortars. Based on the use of a base formulation, available in the literature, eight traces were produced, including four variations of replacement of common sand by recycled aggregate (0%, 25%, 50% and 75%) and two possible combinations of additives, one employing in parallel a superplasticizer additive and a viscosity modifying additive and another in which only one polyfunctional plasticizer additive was applied. Initially, each mixture passed through individual adjustments so as to have adequate consistency, flow time and visual configuration, without demonstrating the occurrence of exudation or segregation. Thereafter, fresh tests were carried out to verify exudation, mass density, incorporated air content and curing time of the mortars. At the end of the research, it was noticed that the incorporation of recycled aggregate in self-leveling mortars could be a technically feasible option, and even advantageous for the mortars formulated with it, considering the evaluated properties, by reducing, among the mixtures with the residue and those ones of reference, the amount of additive employed (up to 0.2%), the exudation (the quantity of water exuded reached 2.04% in a mixture with recycled aggregate and 2.61% in a mixture of reference), the incorporated air content (ranging from 0.17% to 1.34% between traces with and without recycled aggregate) and the mass density (reduced up to 5.5%). Among the combinations of additives, in turn, it was observed that the most satisfactory was the one that employed polyfunctional additive.