Now showing 1 - 2 of 2
  • Publication
    Development of a combined micromechanics & damage mechanics model for the design of asphalt pavements
    Asphalt is a complex, heterogeneous material that is composed of differently sized aggregates, binder and air voids: in other words, it is a particulate reinforced composite. The focus of the present work is to investigate the structural effectiveness of this material composition following the introduction of recycled asphalt pavement (RAP) into the mix. The virgin mortar mix (i.e., matrix) consists of an asphalt binder, sand and crushed rock fines (CRF), while the RAP-containing mix additionally includes fine aggregates ranging in size from fine dust (< 75μm diameter) up to small particles (< 3.35mm diameter). The stress distribution throughout such a material and the resulting mechanical response is strongly related to the interaction between the mix constituents. Previous work has shown that this performance is less influenced by the presence of larger aggregate than it is by the mortar composition and it is for this reason that the present work attempts to model damage evolution in various mortar mixes.
      880
  • Publication
    The influence of recycled asphalt pavement on 20mm binder course mix performance
    This paper presents the results of ongoing research on the mechanical performance of a 20mm binder course asphalt pavement mix incorporating recycled asphalt pavement (RAP). A series of binder course mixes were designed containing varying percentages of RAP. A mix made only from virgin material was selected as the control mix for the investigation. The effect of introducing RAP into the binder course mix was evaluated through a series of laboratory tests including the Marshall Test, Indirect Tensile Stiffness Modulus Test, Indirect Tensile Fatigue Test and Water Sensitivity Test. A Circular Wheel Track (CWT) was developed in order to study the dynamic effects of a rolling wheel travelling over an asphalt pavement. The CWT was commissioned within a temperature controlled room along with a customised Data Acquisition (DAQ) system. The system involves the testing of rectangular slabs and allows for the investigation of the dynamic tensile strain. The dynamic tensile strain is digitally recorded and the loading effect assessed. The laboratory tests have shown that the introduction of RAP to the binder course mix resulted in an improvement in all mechanical properties. This was also observed in the dynamic tensile strain test.
      5789