Doctor of Philosophy (PhD)
Civil and Environmental Engineering
This study aims at (1) enhancing Open Graded Friction Course (OGFC) mixes durability using additives and other by-products; (2) investigating the impacts of selected factors on OGFC pavements seepage characteristics; (3) developing a quantitative tool to model the deterioration in OGFC pavements functional performance; and (4) developing new guidelines of Air Void (AV) content for OGFC for optimum functionality and durability. For the durability objective, eight mixes were prepared with a PG 76-22 binder and two sources of aggregate (i.e., # 78 limestone and # 67 sandstone). Three Warm Mix Additives (WMA), one by-product (i.e., crumb rubber [CR]), and two fillers (i.e., F1 and F2) were evaluated. Results concluded that OGFC durability can be enhanced using WMA, CR, and fillers.
For the second and third objectives, a 3-D Finite Element (FE) model was developed and calibrated based on field measurements. The transient analyses were used to evaluate the impacts of OGFC layer thickness, OGFC permeability, underlying layer permeability, rain intensity, and traffic volume on the seepage characteristics of OGFC. The impacts of these factors were evaluated by calculating the time at which a critical location on OGFC surface reaches overflow condition (TC). The statistical analysis showed that all these factors had a significant impact on the seepage characteristics of OGFC, except OGFC permeability.
Furthermore, an Artificial Neural Network (ANN) model was developed for the prediction of TC without the need for FE modeling. Results indicated that the ANN model predicted TC accurately with R2 of 99 % and 98% in the training and validation stages, respectively. Moreover, this model accurately predicted the deterioration rate of OGFC functionality over time when compared to the results of the FE model. Therefore, this model can be used to determine the time at which routine maintenance should be applied for OGFC pavements. Lastly, simulation runs were conducted using the developed FE model under different AV content conditions ranging from (10 to 24 %) under varying rain intensity conditions. Results revealed that an OGFC layer with an AV content of 16% would provide adequate drainage performance of rainwater while minimizing OGFC durability issues.
Abohamer, Hossam, "A New Generation of Open-Graded Friction Course for Enhanced Durability and Functionality" (2022). LSU Doctoral Dissertations. 5795.