Optimization of mechanical properties in concrete reinforced with fibers from solid urban wastes (PET bottles) for the production of ecological concrete

•The volume of fibers in the concrete affects its compression resistance while the fiber length does not affect this property.•The fiber volume factor and the fiber length can modify the concrete resistance to traction.•The ecological concrete load capacity is higher than the conventional concrete load capacity.•The ecological concrete produced with PET bottle fibers collected from urban solid waste is an alternative for waste management and it could reduce the costs of constructions utilizing asbestos cement. To solve structural problems such as cracks caused by plastic or hydraulic retraction and drying, the modification of concrete properties has been studied through the addition of polymer fibers. The objective of this study was to evaluate the use of fibers from PET bottles on the process of manufacturing ecological concrete, seeking to optimize the mechanical properties of compression and tension. Standardized molding of specimens was performed according to the norms established by the Brazilian Association of Technical Standards (Associação Brasileira de Normas Técnicas – ABNT) for conventional concrete. The results obtained showed that the percent volume of fiber added to the concrete has a direct influence on both the compressive and tensile strength of ecological concrete and that the fiber length has a direct influence on the tensile strength of ecological concrete. The mathematical models generated in this work can be used to predict efficiency values as a function of the operating parameters: PET fiber length and percent volume of PET fiber.