Estudo do uso de agregado reciclado de resíduo da construção e demolição em substituição parcial do agregado miúdo na produção de argamassa estrutural

Abstract

The construction industry, despite its importance for the country's economic development, is a major consumer of natural resources and generator of solid waste. In this context, recycling construction and demolition waste (CDW) appears as a promising alternative, with the potential to reduce the consumption of natural resources and mitigate environmental impacts. The use of mortars with CDW appears as a promising route for this application, with mortars made from composite materials with a cementitious matrix being applicable in several situations. The present study focuses on the application of structural mortar, whose performance parameter followed the guidelines for structural concrete, i.e., compressive strength greater than 20 MPa. To this end, the use of recycled fine aggregates from demolition waste and subjected to different beneficiation processes (crushing in jaw and hammer crushers) for the production of mortars was investigated, analyzing different granulometric compositions between recycled fine aggregates (ARMP, ARSM1, ARSM2) and natural (ANF and ANG). The research methodology involved the characterization of the fine aggregates, analysis of their properties and study of particle packing. The mortars were analyzed in relation to their behavior in the fresh and hardened states. The granulometric characterization of the aggregates demonstrated the compliance of the materials with the limits established by NBR 7211 (ABNT, 2022). The strategic combination of natural and recycled aggregates made it possible to obtain more continuous granulometric distributions, enhancing the mechanical properties of the mortars. The analysis of the recycled aggregates revealed the influence of the crushing process. Using jaw crusher 1 (ARSM1), an aggregate with a more continuous particle size distribution and lower fine content was obtained, which favored compressive strength. Although the mixtures with a higher proportion of recycled aggregates showed lower consistency and greater water absorption, adjustments in the proportions of the aggregates allowed obtaining materials with good workability and strength. The mortars with mixtures of natural and recycled aggregates showed satisfactory performance, highlighting considerable compressive strength results, with idealized mixtures reaching up to 35.51 MPa at 28 days, suggesting that the appropriate combination of natural and recycled aggregates (ARSM1 and ARSM2) can provide a viable alternative for different applications in civil construction. In comparison, the compositions with ARMP tended to present a less favorable performance in terms of compressive strength. In summary, the results of this study confirm the feasibility of using recycled aggregates in the production of structural mortars, as long as the proportions are carefully adjusted.