Pyeong Jun Yoo

Bio: Pyeong Jun Yoo is an academic researcher from University of Illinois at Urbana–Champaign. The author has contributed to research in topics: Ultimate tensile strength & Asphalt. The author has an hindex of 15, co-authored 53 publications receiving 1053 citations. Previous affiliations of Pyeong Jun Yoo include Korea Institute of Civil Engineering and Building Technology.

Viscoelastic Modeling and Field Validation of Flexible Pavements

Abstract: The objective of this study was to characterize hot-mix asphalt (HMA) viscoelastic properties at intermediate and high temperatures and to incorporate laboratory-determined parameters into a three-dimensional finite element (FE) model to accurately simulate pavement responses to vehicular loading at different temperatures and speeds. Results of the developed FE model were compared against field-measured pavement responses from the Virginia Smart Road. Results of this analysis indicated that the elastic theory grossly underpredicts pavement responses to vehicular loading at intermediate and high temperatures. In addition, the elastic FE model could not simulate permanent deformation or delayed recovery, a known characteristic of HMA materials. In contrast, results of the FE viscoelastic model were in better agreement with field measurements. In this case, the average error in the prediction was less than 15%. The FE model successfully simulated retardation of the response in the transverse direction and rapid relaxation of HMA in the longitudinal direction. Moreover, the developed model allowed predicting primary rutting damage at the surface and its partial recovery after load application.

Dynamic Analysis and In Situ Validation of Perpetual Pavement Response to Vehicular Loading

Abstract: A three-dimensional (3-D) finite element (FE) model was developed to predict pavement responses to vehicular loading. The model incorporates measured tire-pavement contact stresses, continuous moving wheel loading, and hot-mix asphalt (HMA) viscoelastic characteristics. The model was fine-tuned using implicit-dynamic analysis and validated using pavement response from accelerated loading. Two tire configurations (dualtire assembly and wide-base 455 tire) and three full-depth flexible pavement designs (HMA 152 mm, 254 mm, and 420 mm) were used in both FE modeling and accelerated loading tests. The predicted and calculated strain responses at the bottom of HMA were in agreement. Most important, the study shows that vertical shear strain in the upper 76 to 100 mm of the pavement surface is critical for thick pavement and is influenced by the 3-D tire-pavement contact stresses under each tire rib. However, the tensile strain at the bottom of HMA is affected mainly by the total wheel load. The vertical shear s...

Flexible pavement responses to different loading amplitudes considering layer interface condition and lateral shear forces

Abstract: A three-dimensional (3D) finite element (FE) parametric study was conducted to quantify the viscoelastic pavement responses due to different tire configurations: dual and wide-base tires, at three temperatures (5, 25 and 40°C) and two speeds (8 and 72 km/h) Three factors affecting pavement responses were investigated: type of moving wheel loading amplitude (continuous, trapezoidal), interface layer condition (simple-friction and elastic-stick models) and lateral surface forces It was found that the continuous loading amplitude, which has an asymmetric stress magnitude and considers the difference between the entrance and exit of the tire, can simulate pavement responses to moving wheel vehicular loading more accurately than the currently used trapezoidal loading amplitude The elastic-stick model resulted in a sensible improvement for predicting pavement responses to dual tire, while the simple-friction model is more comparable to field measurements in the case of the wide-base tire The shear force was

Effect of Transient Dynamic Loading on Flexible Pavements

Abstract: The effect of transient dynamic loading on flexible pavements was estimated. Transient dynamic loads within a tire-to-pavement contact area are characterized by continuously increasing or decreasing local dynamic contact stresses, depending on vehicle speed. A transient dynamic load model was successfully incorporated into a three-dimensional finite element model. Dynamic flexible pavement responses to one pass of a heavy vehicular load through a dual-tire assembly were calculated. Results of this study indicate that the flexible pavement response at different pavement temperatures varies depending on whether the analysis was quasi-static or dynamic, where the mass inertia and damping forces by the transient local dynamic loads are considered in the equation of motion. Results also show that the time-dependent history of the calculated pavement responses in the dynamic analysis is more comparable to measurements in the field. The transverse and longitudinal tensile strains at the bottom of the hot-mix asphalt and the compressive stress at the top of the subgrade are underestimated when the mass inertia and damping forces exerted by the transient local dynamic load are ignored.

Influence of Six Rejuvenators on the Performance Properties of Reclaimed Asphalt Pavement (RAP) Binder and 100% Recycled Asphalt Mixtures

Abstract: 100% recycled hot mix asphalt lab samples were modified with five generic and one proprietary rejuvenators at 12% dose and tested for binder and mixture properties. Waste Vegetable Oil, Waste Vegetable Grease, Organic Oil, Distilled Tall Oil, and Aromatic Extract reduced the Superpave performance grade (PG) from 94–12 of extracted binder to PG 64-22 while waste engine oil required higher dose. All products ensured excellent rutting resistance while providing longer fatigue life when compared to virgin mixtures and most lowered critical cracking temperature. Rejuvenated samples required more compaction energy compared to virgin and some oils reduced moisture resistance slightly.

Viscoelastic Modeling and Field Validation of Flexible Pavements

Abstract: The objective of this study was to characterize hot-mix asphalt (HMA) viscoelastic properties at intermediate and high temperatures and to incorporate laboratory-determined parameters into a three-dimensional finite element (FE) model to accurately simulate pavement responses to vehicular loading at different temperatures and speeds. Results of the developed FE model were compared against field-measured pavement responses from the Virginia Smart Road. Results of this analysis indicated that the elastic theory grossly underpredicts pavement responses to vehicular loading at intermediate and high temperatures. In addition, the elastic FE model could not simulate permanent deformation or delayed recovery, a known characteristic of HMA materials. In contrast, results of the FE viscoelastic model were in better agreement with field measurements. In this case, the average error in the prediction was less than 15%. The FE model successfully simulated retardation of the response in the transverse direction and rapid relaxation of HMA in the longitudinal direction. Moreover, the developed model allowed predicting primary rutting damage at the surface and its partial recovery after load application.