Estudo sobre a resistência à compressão do concreto com agregado reciclado

Abstract

Concrete is one of the most used materials in the world, and in Brazil, this scenario is no different, since most constructions corroborate this fact. It is worth noting, as regards its composition, the use of natural granular materials (coarse and fine aggregates) which represent a portion of approximately 75% of the volume of concrete produced. From this perspective, because of the growing mineral extractive demand, alternative solutions for the reuse of materials have been proposed to minimize the environmental impacts arising from the extraction, processing, and transport of natural aggregates, as well as waste generated by civil construction (RCC). Thus, the present work aimed to analyze the recycled aggregates, as well as to study their influence on the compressive strength of conventional concrete, from the results of the tests that involved the characterization of the aggregates to the analysis of the fresh and hardened states of the concrete. with recycled concrete aggregates (ARC). The maximum characteristic dimensions of the fine and coarse aggregates were, respectively, 4.75 mm and 12.5 mm, obtained from the passage through the jaw and hammer crushers. Recycled aggregates had lower specific mass and higher water absorption than natural aggregates. 3 mixtures were produced with different percentages of replacement of the natural aggregate. The control mixture was produced with 100% fine and coarse natural aggregates, the others replacing 50% and 100% of both with ARCO. Concerning the production of mixtures, the method proposed by ABCP was used with a target strength of 20MPa. The recycled aggregates underwent pre-wetting for 15 minutes, as a way of mitigating their high water absorption. Fifteen specimens were molded for the compressive strength test for the ages of 7, 14, and 28 days. From the results of the consistency test, voids index, and water absorption, all mixtures obtained high values. Furthermore, from the compressive strength tests at 28 days, the mixture with 100% natural aggregate reached 27.55 MPa, however, the mixture produced with 50% recycled aggregates showed a result of 24.38 MPa, above the target value. Only the mixture with 100% ARC did not reach the target value, obtaining 18.31 MPa. The results demonstrated the potential of using ARCO in terms of use for structural purposes, although the current regulatory standard limits the replacement of natural aggregate to just 20%.