ABSTRACT
This chapter describes the influence of the introduction of recycled aggregates (RA) on the instantaneous properties of concrete. In the first part, existing models linking compressive and tensile strength and elastic modulus of natural aggregates concretes (NAC) to their mix design are validated and adapted for recycled aggregates concrete (RAC). These models make it possible to consider properly and on a case-by-case basis the respective quality of NA and RA in the mix design process of RAC. In the second part, more global and statistical models describe the effect of the introduction of RA on compressive and tensile strength, elastic modulus, and peak and ultimate. This section provides elements of reflection for an extension of the design codes to the case of RAC. It was thus pointed out that design codes relationships dedicated to assess the mechanical properties and the stress–strain compressive curve of NAC are not adequate to predict the behavior of RAC. It is established that the elastic modulus E cm, the tensile splitting strength f ctm,sp, the peak strain ε c1 and the ultimate strain ε cu1 are related to the mean compressive strength f cm and to a parameter taking into account the effect of the recycled aggregates replacement rate. Furthermore, an analytical stress–strain expression is proposed for concretes incorporating recycled aggregates.
