Master of Science in Civil Engineering (MSCE)
Civil and Environmental Engineering
The primary objective of this study is to evaluate the effects of asphalt concrete (AC) properties and vehicle speed on fuel consumption excess using a Three-Dimensional (3D) Finite Element (FE) approach. Secondarily, the effect of pavement design characteristics on energy dissipation was studied. Finite element modeling was used to simulate three flexible pavements typically used for low traffic volume, medium traffic volume, and high traffic volume. The effect of asphalt concrete mixes with different binders and varying percentages of Reclaimed Asphalt Pavement (RAP) on fuel consumption excess was studied. The FE models were validated based on field stress and strain measurements at the Louisiana Accelerated Loading Facility (ALF). Energy dissipation was calculated for the whole model due to materials’ viscous properties and was used as an input in fuel consumption estimation. Results indicated that the pavement with the stiffer mix, i.e., the mixes with high percentage of RAP consumed less energy. Therefore, fuel savings can be expected when increasing the stiffness of asphalt layer using RAP materials. However, the fuel consumption due to energy dissipation constitutes only a very small fraction of the total vehicle fuel consumption. An increase in energy dissipation of 0.5 MJ/100mile was observed to yield a corresponding 0.013 gal/100mile increase in fuel consumption to overcome the energy dissipation for an 18-wheeler truck at 60 mph. Fuel consumption excess was lowest at the highest speed and increased with decreasing speed. The fuel consumption excess was higher for pavements with greater thickness of AC layer, indicating a considerable impact of AC thickness on fuel consumption excess. Results for fuel consumption excess on medium and high traffic volume flexible pavements suggested that the thickness of the sub-layers other than HMA layer have a negligible effect on energy dissipation.
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Dhakal, Nirmal, "Evaluation and Validation of a Model to Predict the Effect of Asphalt Mixtures and Vehicle Speed on Fuel Consumption Excess" (2016). LSU Master's Theses. 828.