Recycling of tire rubber and concrete residue in the production of concrete bricks: Dosing and optimization

Abstract

The volume of solid waste produced has been increasing in a disorderly and damaging way to nature, since it is not given adequate purposes. As waste that can be used in the manufacture of concrete bricks, there is tire rubber, a major cause of environmental problems, and the cementitious waste generated in concrete plants, called Concrete Sludge Waste (CSW). The general objective of this study will then be to determine a concrete mix for brick production that contains higher percentages of concrete sludge waste and tire rubber gran-ulate, together. For this purpose, the Central Composite Delineation of Rotational was used as experimental planning and the data evaluated via Response Surface Methodology, with the waste tire rubber granulate replacing the aggregate and the Concrete Sludge Waste in its dry state (CSW-S) to the cement. The physical-chemical characterization of the aggregates, compressive strength and water absorption of the bricks were carried out. The results showed that it is feasible to use the CSW-S and the waste tire rubber granulate, ob-taining an optimal trace that presents compressive strength of 7.9 MPa and 8.8% of water absorption, meet-ing the limit of 3 MPa of compressive strength and 10% water absorption of ABNT NBR 6136:2014. The optimum line was produced with 4% rubber and 15% LRC-S, replacing aggregate and cement, respectively. It is noteworthy that the higher the percentage of rubber, the lower the resistance to compression and the greater the water absorption, being that the limit of replacement of the rubber depends on the aggregate used, the molding conditions and the line used.