LABORATORY PERFORMANCE-BASED APPRAISAL OF HALF-WARM MIX RECYCLED ASPHALT MIXTURES CONTAINING UP TO 50 % OF RECLAIMED ASPHALT PAVEMENT

The use of greener paving technologies involving recycling material and emulsified bitumen is gaining momentum in the recent years as a way to improve environmental performance, reduce pollutant emissions and energy consumption. Thus, one of the leading objective of this research paper is to present the main performance outcomes obtained of an extensive laboratory study to account for, and determine the volumetric and mechanical performance properties of both half-warm mixes (HWMA) and half-warm mix recycled asphalt (HWMRA) mixtures containing two different rates of reclaimed asphalt pavement (25 % and 50 % RAP), with an over-stabilized bituminous emulsion, and, thereafter, compared them with that of a conventional HMA mixture. To do so, both HWMA and HWMRA mixes were designed in the laboratory using the Duriez mix design method in order to calculate the optimal binder film thickness required to achieve a high level of performance and durability of the mixes based on the specific surface area (SSA) of aggregates. Posteriorly, the mixture performance was studied and tested in the laboratory in order to determine the apparent density, air voids, water susceptibility, indirect tensile strength (ITS), at 15 degrees C, stiffness modulus at 20 degrees C, and rutting performance, at 60 degrees C. The results of laboratory showed that the performance of the HWMRA mixtures containing a high RAP content (50 %), and a 50/70 pen-grade bitumen, exhibited an equivalent permanent deformation and moisture damage resistance to the conventional HMA mixture. These findings encourage and strengthen greater confidence in promoting the use of these types of sustainable asphalt mixes.