Flexural Behavior of Concrete Mixtures with Waste Tyre Recycled Aggregates

The huge quantity of natural aggregates extracted every year and used for concrete industry is causing harmful consequences on biodiversity, water turbidity, water table level and landscape, and on global warming as well. In this context, many studies focused on the possibility to use waste tyre recycled aggregates as partial replacement of stone aggregates in concrete production. Generally, it has been observed that several mechanical properties, such as compressive strength and modulus of elasticity, significantly decrease when rubber content is increased. On the other hand, rubberized concrete (RuC) showed a more ductile behavior than ordinary Portland cement concrete, in addition to a greater damping and energy dissipation capacity. In this paper the compressive and flexural strength, the water permeability and thermal conductivity, of five concrete mixtures, with increasing percentages of rubber particle as partial replacement of natural aggregates, have been investigated. As a result, a reduction in compressive strength has been observed only in RuC mixtures with substitutions greater than 12% of the total aggregates, whereas the flexural strength remained roughly constant. Moreover, the results of water permeability and thermal conductivity tests showed respectively a decrease in water penetration and an improvement of the concrete thermal isolation due to the presence of rubber particles.