Laboratory Characterization of Half-Warm Mix Asphalts with High Recycling Rate by Means of the Factorial Experiment Design Approach

In-plant reclaiming at strong rate is more and more often used. Nowadays, some asphalt plants enable a 70% recycling rate whatever the production temperature (hot-mix or warm-mix asphalt). This study aimed at determining the influence of the mix composition on the performantial properties of half-warm mix asphalts, produced in laboratory at approximately 95°C following the innovative proprietary low energy asphalt technique labeled LEA®. By means of the factorial experiment design approach, this study highlights the influence of the bitumen pen grade (10/20, 35/50 and 50/70), the RAP content (30%, 50% and 70%) and the vegetable additive content used in the LEA process (0.2%, 0.6% and 1%). Many laboratory tests were conducted, including the French gyratory shear compacting press, the Duriez test (evaluation of water resistance) and the stiffness modulus. This laboratory characterization shows that very high recycling rates (from 30% to 70%) can be used in half-warm mix asphalts.