Concreto alternativo com utilização de resíduos de borracha de recauchutagem de pneus para elementos e componentes pré-fabricados

Abstract

Unserviceable tires represent an environmental passive of difficult final disposition, both because of their big volume and because of their lengthy decomposition. Discarding them inadequately causes important damages to the environment and favors the proliferation of vectors of human diseases. The retreading industry is key to extend the service life of pneumatics, but the volume of waste generated in this process increases as a consequence. The use of waste from industrial processes such as tire retreading has seen a rise as an option for the reutilization of materials. In order to contribute to the reversal logistics of unserviceable tires, this work aims at evaluating the influence of the incorporation of different proportions of tire retread rubber waste (6 wt% and 9 wt%) in a concrete of alternative composition to be used in prefabricated elements and components applied in construction. The experimental procedures conducted include: physical characterization of the residues and other materials in the mixes; determination and production of concrete mixes and confection of specimens; physical (specific weight, absorption and voids content) and mechanical tests (axial compressive strength, diametric compressive strength, tensile strength and elasticity modulus), and; macroscopic and microscopic analysis with the utilization of stereoscope and Scanning Electron Microscope (SEM). Finally, a quantitative assessment of the environmental benefits of the use of the residue was elaborated, as well as an analysis of the costs of manufacturing a concrete with rubber. The results showed that all the mixes analyzed present axial compressive strength higher than 35 MPa and absorption lower than 6%, in accordance to the guidelines of NBR 9781 (ABNT, 2013), for the use in the manufacture of prefabricated elements and components. The concrete with 9 wt% of incorporated rubber residue presented an increase in the crack resistance (19.14% when compared to the reference mix) and a decrease of 3.04% in its specific weight. The manufacture costs were 4% lower than those of regular concrete. From the analysis, the technical, economic and environmental viability of this alternative has been established, being it useful in the manufacture of paving elements of satisfactory quality according to the most accepted technical standards.