Mechanical and thermal properties of concrete incorporating rubber and fibres from tyre recycling

In this paper, an analysis of the mechanical and thermal properties of a sustainable concrete incorporating crumb rubber (CR) and steel or plastic fibres partially coated with rubber (FCR) is presented. Whereas CR is normally used as aggregate in concrete, FCR is a new aggregate. FCR consists of fibres partially coated with crumb rubber recovered from the tyre recycling process, during granulation and before the total separation of rubber. The mechanical properties of concrete with rubber getting up to 100% volume substitution of stone aggregate have been obtained through compressive, bending, impact and wear resistance tests. Young's modulus, toughness, toughness index and impact energy absorption are also studied. Concrete with FCR aggregate presents the same or even better mechanical behaviour than conventional rubberized concrete. The thermal conductivity (k) of concrete with FCR as aggregate is comparable to the k of concrete with CR, and it is also lower than the reference concrete. Finally, some proposals of constructive systems with rubberized concrete for thermal rehabilitation of buildings are analysed using pseudotime-dependent software, for which a significant reduction of the thermal fluxes can be observed.