Now showing 1 - 5 of 5
  • Publication
    The influence of recycled asphalt pavement on the fatigue performance of asphalt concrete base courses
    (American Society of Civil Engineers, 2010-06) ; ; ;
    This paper presents the physical properties of Recycled Asphalt Pavement (RAP) and its influence on the mechanical performance of a binder course asphalt pavement mix. A series of binder course mixes were designed containing varying percentages of RAP. A mix made from only 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, the indirect tensile stiffness modulus Test, the indirect tensile fatigue test and the 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 system. The system involves the testing of rectangular slabs and allows for the investigation of dynamic tensile strain. The laboratory tests have shown that the introduction of RAP to the binder course mix resulted in an improvement in all mechanical properties. In particular, it was found that the mix containing up to 30% RAP, displayed improved fatigue resistance relative to the control mix manufactured from virgin materials.
    Scopus© Citations 70  2602
  • Publication
    Modelling the quasi-static behaviour of bituminous material using a cohesive zone model
    This paper investigates the applicability of a cohesive zone model for simulating the performance of bituminous material subjected to quasistatic loading. The Dugdale traction law was implemented within a finite volume code in order to simulate the binder course mortar material response when subjected to indirect tensile loading. A uniaxial tensile test and a threepoint bend test were employed to determine initial stress-strain curves at different test rates and the cohesive zone parameters (specifically, fracture energy and cohesive strength). Numerical results agree well with the experimental data up to the peak load and onset of fracture, demonstrating the value of the cohesive zone modelling technique in successfully predicting fracture initiation and maximum material strength.
      1722Scopus© Citations 25
  • 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.
      5791
  • Publication
    Fatigue resistance of bituminous layers incorporating reclaimed asphalt pavement
    This paper presents the results of an investigation into the fatigue performance of a 20mm Binder Course Asphalt Pavement Mix incorporating Recycled Asphalt Pavement (RAP). For the study, 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. A Circular Wheel Tracker (CWT) was developed in order to simulate the dynamic loading conditions of a rolling wheel and to study the initiation and growth of fatigue cracks in an asphalt pavement mix. The CWT was commissioned within a temperature-controlled room with a customised data acquisition system. The test specimens were subjected to dynamic loading in the CWT and the dynamic strain on the underside of the slab was monitored throughout the test. A digital image processing technique was also used to measure the crack area and crack length at the underside of the test specimen. Parallel to this a separate testing programme was undertaken, whereby the fatigue resistance of bituminous mixtures incorporating same RAP contents was assessed using the indirect tensile fatigue test as described in BS DD ABF:1997. The results from these parallel strands are compared, and the performance of the various mixes incorporating RAP is assessed.
      2956