Análise de propriedades mecânicas de concretos produzidos com diferentes dosagens de agregados reciclados de concreto

Abstract

Currently, smarter alternatives have been sought within the civil construction sector, as a way to reduce harmful interference to the environment. Among these alternatives, the use of recycled concrete aggregates stands out for the production of mortars and concrete, with or without a structural function. However, the use of these aggregates is a subject that still needs studies, in the sense of seeking alternatives that aim to understand the interference of replacing these aggregates in the production of new concrete for abandoned purposes. Thus, the main objective of this study is to evaluate the contribution of recycled concrete aggregate (ARC) dosages on the properties of integrated concrete in the fresh and long-lasting states. Concretes with different dosages were produced, using the method proposed by ABCP, varying the percentage of replacement of natural aggregate by recycled in 25%, 50%, 75% and 100%, as well as varying the size of the ARCO (small and big). Fresh state performance was evaluated using the slump test. The evaluation of the properties in the durable state was carried out using the resistance to syndrome test, modulus of elasticity and physical indices of concrete, such as water absorption, voids index and real density. From the results of the consistency test, voids index, and absorption, all mixtures showed high values. With regard to the results of resistance to flex at 28 days, the mixtures produced showed advanced values with results above 20 MPa, it was also proven that the resistance was supported with the increase in the percentage of substitution of the recycled concrete aggregate, being more evident in mixtures with replacement of coarse aggregate only. In this way, the interference of the size of the aggregate in the properties of concrete is evident, both in the fresh state and in the lasting state. Complementarily, the results justified the potential use of ARCO, with the possibility of replacing the natural aggregate in large part, as opposed to the current standard, which limits the percentage of replacement to up to 20% in applications for functional purposes (resistance class of C20), without bringing a clear indication if this replacement refers to fine aggregate, coarse aggregate or both.