Civil, Environmental, and Geospatial Engineering News

Category: Seminars

The Properties of Modified Asphalt Binders Blended with Electronic Waste Powders

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Civil Engineering CE 5990 Graduate Seminar

Thursday, January 26
Time: 4–5 p.m.
Location: Dow 642
Public is welcome

Presenter: Baron Colbert, Ph.D. candidate, Department of Civil and Environmental Engineering (Adviser: Dr. Zhaping You)

Abstract: This study was intended to successfully implement asphalt binders modified with electronic waste (e-waste) from recycled computer plastics in order to improve asphalt binder performance versus conventional asphalt binders. The e-waste powder percentages blended with asphalt binders were 2.5%, 5%, and 15%, respectively. Rotational viscosity, dynamic shear rheometer testing, and bending beam rheometer testing was conducted upon modified and virgin asphalt binder samples. The addition of e-waste powders increased binder viscosity, blending and mixing temperatures, decreased rutting susceptibility versus virgin asphalt binders, and lower percentages of e-waste powders modified asphalt binders resulted in similar m-values at the specified low temperature grade of the control asphalt binder.

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Development of Dynamic Asphalt Stripping Machine for Better Prediction of Moisture Damage of Porous Asphalt Pavement in Malaysia

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Civil Engineering CE 5990 Graduate Seminar

Thursday, January 26
Time: 4–5 p.m.
Location: Dow 642
Public is welcome

Presenter: Mohd Rosli Bin Mohd Hasan, Ph.D. candidate, Department of Civil and Environmental Engineering, (Adviser: Dr. Zhaping You).

Abstract: Stripping is a major source of pavement distress and takes place in the presence of moisture. Over the years, many laboratory tests have been proposed to evaluate moisture sensitivity of asphalt mixtures. This seminar will cover the development of a dynamic asphalt stripping machine (DASM) to realistically simulate stripping of porous asphalt mixtures subjected to the dynamic action of flowing water, especially for the Malaysia condition. The topic also covers the background of invention, operational steps and preliminary evaluation on the DASM based on the permeability and indirect tensile strength test results.

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The Aging Properties of SBS Modified Bitumen and Its Recycling

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Civil Engineering CE 5990 Graduate Seminar

Thursday, January 19
Time: 4–5 p.m.
Location: Dow 642

Public is welcome

Speaker: Dr. Xiaoming Huang, Professor, Associate Dean, School of Transportation, Southeast University, China Brief

Abstract: In China, following the huge new highway constructions, large portion of the highway network needs to be maintained and rehabilitated. Reclaimed asphalt material has been studied, produced and used for pavement rehabilitations. This lecture will cover the study of aging of the modified asphalt binder, the influence of mineral filler and trichloroethylene. The lecture will also cover an introduction of research in pavement engineering in China as well as the research in Southeast university in China.

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Two- and Three-Dimensional Micromechanical Constitutive Modeling of Heterogeneous Infrastructure Materials with X-Ray Computed Tomography Images

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Civil Engineering CE 5990 Graduate Seminar

Thursday, Jan. 12
Time: 4-5 p.m.
Location: Dow 642

Public is welcome

Presenter: Dr. Qingli Dai, Assistant professor, Department of Civil and Environmental Engineering.

Abstract: This study developed two-dimensional (2D) and three-dimensional (3D) micromechanical finite element (FE) models to study the viscoelastic properties of heterogeneous infrastructure materials. For example, asphalt mixtures are consisted of very irregular aggregates, asphalt matrix and a small amount of air voids. The internal microstructure of asphalt mixtures was captured with X-ray Computed Tomography (CT) imaging techniques. The 2D and 3D digital samples were created with the reconfiguration of the scanned slice images. The FE mesh of digital samples was generated with the locations of image pixels within each aggregate and asphalt matrix. Along the boundary of these two phases, the aggregate and matrix FEs share the nodes to connect the deformation. The micromechanical FE modeling was conducted by incorporating the captured microstructure and ingredient properties (viscoelastic asphalt matrix and elastic aggregates). The generalized Maxwell model was applied for viscoelastic asphalt matrix with calibrated parameters from the nonlinear regression analysis of the lab test data. The 3D simulation with digital samples generated better prediction than the 2D models. These favorable comparison results indicate that the developed micromechanical FE models have the ability to accurately predict the global viscoelastic properties of the heterogeneous infrastructure materials.

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An EXtended Finite Element Model (XFEM) for Predicting Crack Propagation within Infrastructure Materials

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Thursday, Jan. 12
Time: 4-5 p.m.
Location: Dow 642

Public is welcome

Presenter: Kenny Ng, Ph.D. candidate, Department of Civil and Environmental Engineering, (Adviser: Dr. Qingli Dai).

Abstract: The object of this study is to employ XFEM and image analysis techniques to numerically investigate crack propagation within infrastructure materials. The XFEM has been recently developed to eliminate remeshing by allowing crack propagation within continuous elements. The discontinuous crack and inclusion enrichment functions with level set method (LSM) were addressed in the XFEM. The crack growth angle and stress intensity factors (SIFs) were also formulated to predict the crack growth direction. The XFEM was developed with MATLAB program for predicting micro-crack behavior with Compact Tension (CT), single-edge notched beam (SEB) and indirect tension (IDT) tests. The developed XFEM was firstly validated with CT and SEB tests on a homogeneous sample. In order to capture the real material microstructure, the digital samples were generated with imaging processing and ellipse fitting techniques. The predicted crack propagation with XFEM simulation on digital samples was compared with fracture pattern of lab-tested SEB and IDT specimens. The comparison results on open-mode middle-notched and mixed-mode offset-notched SEB and IDT tests indicate the developed XFEM has the ability to accurately predict fracture behavior within heterogeneous infrastructure materials. In addition, the internal frost-induced damage within an idealized pore system was also analyzed and simulated using XFEM.

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