Durability of European Asphalt Mixtures Containing Reclaimed Asphalt and Warm-Mix Additives

This paper investigates the moisture susceptibility of European asphalt mixtures (SMA) containing reclaimed asphalt (RA) and warm mix (WMA) additives. Test sections of a typical SMA mixture have been laid, from which cylindrical samples were cored and utilized for laboratory testing. Four variants of the SMA mixture were prepared; a control HMA mixture with 0% RA, a mixture with 30% RA and no WMA additive, a mixture with 30% RA in which a WMA additive was added and a mixture with 40% RA and a WMA additive. The coring procedure and testing were carried out in two phases; first field cores were taken 24 hrs after the construction of the test section was completed and then once again 12 months later. In this way, the influence of field aging on the mechanical performance of the mixtures was considered. The samples were moisture conditioned at various combinations of water bath immersion and cyclic pore pressures by means of the Moisture Induced Sensitivity Tester (MiST). The degradation in strength due to moisture was quantified through indirect tensile strength tests. The results indicated that the use of RA in combination with WMA additives resulted to mixtures with improved durability characteristics, with respect to moisture damage, compared to the control HMA mixture. Based on the results, recommendations were made for characterizing and limiting moisture damage of asphalt pavements.harvestPavement Engineerin

The Influence of Air Void Content on Moisture Damage Susceptibility of Asphalt Mixtures: A Computational Study

Because of the difficulties associated with the generation of finite element meshes based on X-ray computed tomography scans and with the extraordinary computational demands in performing three-dimensional (3-D) finite element analyses, past modeling efforts have focused primarily on two-dimensional representations of asphalt mixtures and have placed no emphasis on the inclusion of the air voids network in the body of an asphalt concrete specimen. A 3-D micromechanical moisture damage model has been developed and implemented in the finite element system CAPA-3D capable of addressing individually the three main phases of asphalt concrete: aggregate, mastic, and air voids. The 3-D finite element meshes of different types of asphalt mixtures were generated on the basis of X-ray scans. By means of CAPA-3D, the significance of the air voids structure in the development of moisture damage in asphalt concrete specimens was demonstrated. Availability of the model enables evaluation and ranking of the contribution of the characteristics of the individual mixture components to the overall mixture moisture resistance.Structural EngineeringCivil Engineering and Geoscience