Now showing 1 - 4 of 4
- PublicationFull scale accelerated testing of bituminous road pavement mixturesThe in-service behaviour of a standard Irish Dense Base Coarse Macadam mixture (DBC) was evaluated by using the material to overlay a road section, which was based upon a weak pavement structure. The response of the layer under a fully laden dual axle truck was examined using a series of pressure cells and asphalt strain gauges that were embedded in the test section. The section was traversed repeatedly until a network of fatigue cracks was observed on the road surface. The transverse horizontal tensile strain was found to be the most critical parameter in initiating pavement damage
- PublicationRegional integration of renewable energy systems in Ireland - The role of hybrid energy systems for small communitiesDue to a lack of indigenous fossil energy resources, Ireland's energy supply constantly teeters on the brink of political, geopolitical, and geographical unease. The potential risk to the security of the energy supply combined with the contribution of anthropogenic greenhouse gas emissions to climate change gives a clear indication of Ireland's need to reduce dependency on imported fossil fuels as primary energy source. A feasibility analysis to investigate the available renewable energy options was conducted using HOMER software. The net present cost, the cost of energy, and the CO2 emissions of each potential energy combination were considered in determining the most suitable renewable and non-renewable hybrid energy system. Wind energy was shown to have the greatest potential for renewable energy generation in Ireland: wind energy was a component of the majority of the optimal hybrid systems both in stand-alone and grid-connected systems. In 2010 the contribution of wind energy to gross electricity consumption in Ireland approximated 10%, and the results of this feasibility study indicate that there is great potential for wind-generated energy production in Ireland. Due to the inherent variability of wind energy the grid-connected system results are particularly relevant, which show that in more than half of the analyses investigating electrical energy demand the incorporation of wind energy offset the CO2 emissions of the non-renewable elements to such a degree that the whole system had negative CO2 emissions, which has serious implications for Kyoto Protocol emissions limits. Ireland also has significant potential for hydropower generation despite only accounting for 2% of the gross electricity consumption in 2010. Wind and hydro energy should therefore be thoroughly explored to secure an indigenous primary energy source in Ireland.
Scopus© Citations 68 1771
- PublicationMinimizing Distress on Flexible Pavements Using Variable Tire PressureThe potential of variable tire pressure technology to minimize distress on flexible pavements with thin asphalt surfacing layers and peat soil subgrade was evaluated using in-situ stress-strain data. Pavement interfacial strains and corresponding subgrade stresses imposed by a three-axle truck were measured and used to estimate the fatigue life of the surfacing layer. Three levels of truck wheel loads in combination with four tire inflation pressures (350, 490, 630, and 770 kPa) were used to evaluate the potential distress by the single steering wheel and rear dual wheels in tandem. Results suggest that lateral strain due to the single steering wheel is the most critical to fatigue failure, which is influenced by the viscoelastic nature of asphalt, and therefore truck speed and axle configuration are important. Lower tire pressures increased the fatigue life of the surfacing layer with respect to the rear dual wheels and the steering wheel by up to 200 and 300%, respectively. Haulage trucks with systems for managing variable tire pressure such as the central tire inflation systems may therefore enhance the serviceability of pavements overlying peat or other soft soil foundations.
Scopus© Citations 51 868
- PublicationIn-situ Accelerated Testing of Bituminous MixturesThe in-service behaviour of a standard Irish Dense Base Coarse Macadam mixture (DBC) was evaluated by using the material to overlay a road section, which was based upon a weak pavement structure. The response of the layer under a fully laden dual axle truck was examined using a series of pressure cells and asphalt strain gauges that were embedded in the test section. The section was traversed repeatedly until a network of fatigue cracks was observed on the road surface. The transverse horizontal tensile strain was found to be the most critical parameter with respect to crack initiation. When based on in-situ measured strain data, the analytical model that was developed to predict pavement performance on the basis of fundamental laboratory test data, was found to underestimate the in-service fatigue life of the DBC mixture by a factor of 13.5. The underestimation may be attributed to factors that are not accounted for in the analytical models such as material healing, traffic wander and in-situ environmental , which possibly lead to lower fatigue estimates.