Modelling of Mechanical Properties of Cement Concrete Incorporating Reclaimed Asphalt Pavement

In many countries there is a trend to recycle wastes obtained (luring pavement maintenance or reconstruction, and to forbid the landfill of these products. Thus, in some circumstances it can be tempting to use reclaimed asphalt pavement (RAP) in new hydraulic concrete mixtures. This paper presents experimental data and modelling about the effect of RAP incorporation on cement concrete mechanical properties (compressive strength, tensile strengths and F modulus). All these properties tend to decrease with the rate of RAP dosage, and with temperature. Then attempts are made to adapt LCPC mix-design models to these innovative concretes. Two alternative hypotheses are evaluated. In the first one, RAP aggregate is viewed as composite particles playing the role of an homogenous aggregate having lower bond, strength and F-modulus its compared to normal aggregate. In the second one, the bitumen phase is assumed to be finely dispersed within the cement paste, acting as a supplementary dosage of water (or air). According to the simulations, the second hypothesis is the best one. This finding extends the scope of application of modern mix-design methods, and will help in using RAP in cement concrete, for the technical, economical and environmental benefit of the road community.