Now showing 1 - 4 of 4
  • 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  2634
  • Publication
    The first semester of university life ; ‘will I be able to manage it at all?’
    This paper reports on an Irish study examining first year students’ recollections of their concerns, motivations, level of preparedness and perceived skills on entry to university. The study aims to investigate and understand the implications of the attitudes of first year students as they make the transition to university. It also explores students’ behaviour during their initial weeks at university. It is important to understand the anxieties of new students, their views on their abilities and their confidence in managing their new role as these factors will have consequences for their experience as first year university students. These findings are explored with a view to enhancing the quality of support for students during this key transition.
      3214Scopus© Citations 46
  • 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.
      1752Scopus© Citations 25
  • Publication
    Development of a recycled polymer modified binder for use in stone mastic asphalt
    The number of commercial vehicles using Irish roads has increased considerably in recent years, leading to higher demands being placed on pavement materials and increased use of polymer modified bitumens. This has also coincided with significant changes in Governmental policy which has produced large increases in Irish recycling rates. Improved recycling levels are set to provide Ireland with a new challenge: to find potential uses for the large quantities of recycled polymer that are becoming available. Towards this end, the potential of developing a recycled polymer modified binder was investigated. The polymers most commonly recycled in Ireland were identified and sourced from industry. Fundamental bitumen tests were conducted to assess the effect of the recycled polymer and a mixing methodology developed. It was found that the addition of 4% recycled HDPE into a pen grade binder produced the most promising results, and the mixing process was then optimised with respect to mixing parameters and binder additives. A developmental recycled binder was produced and compared in performance tests to binders currently used in road construction practice. Results obtained from wheel track and fatigue tests show that although the binder does not deliver equivalent performance levels to a proprietary polymer modified binder, it does out-perform traditional binders used in stone mastic asphalt. Recommendations are offered on the further development of the recycled polymer modified binder to achieve the standards currently required.
      8083Scopus© Citations 173