Publications

Published: 02/05/2019

By: Behzad Behnia, William G. Buttlar, and Henrique Reis

An acoustic-emission approach to evaluate the low-temperature cracking performance of asphalt binders is presented. The acoustic activity of a thin film of asphalt binder bonded to a granite substrate is monitored while the layer is exposed to decreasing temperatures from around 20°C to approximately −50°C. Results of eight different asphalt binders at three different aging

Published: 01/10/2019

By: William G. Buttlar, Jim Meister, Behnam Jahangiri, and Hamed Majidifard

A comprehensive lab and field investigation was carried out to evaluate the performance of recycled asphalt mixtures in Missouri by researchers at the University of Missouri-Columbia, in collaboration with the Missouri Department of Transportation and the Midwest Transportation Center. Sixteen field sections were evaluated, including a number of sections from the recent Long-Term Pavement Performance

Published: 12/11/2017

By: Oliver Giraldo-Londoño, Daniel W. Spring, Glaucio H. Paulino, William G. Buttlar

Highlights An efficient mixed-mode rate-dependent cohesive zone model is presented in detail. Rate-dependent springs and damage elements are coupled to model mixed-mode fracture. The model is implemented as a user-defined element in Abaqus. The model results agree well with test results for a wide range of strain rates. The accuracy of the model is similar

Published: 01/25/2017

By: B. C. HillO. Giraldo-LondoñoG. H. PaulinoW. G. Buttlar

Tensile cracking in asphalt pavements due to vehicular and thermal loads has become an experimental and numerical research focus in the asphalt materials community. Previous studies have used the discrete element method (DEM) to study asphalt concrete fracture. These studies used trial-and-error to obtain local fracture properties such that the DEM models approximate the experimental

Published: 06/21/2016

By: Brian Hill, William G. Buttlar

Asphalt polymer modification typically yields improved mixture performance. Little research has been conducted to determine how SBS polymer affects mixture performance in interaction plots. Furthermore, research to date has not used digital image correlation to measure the fracture process zone (FPZ) size and its compression with crack propagation. Mixtures containing five distinct asphalt binders were

Published: 02/03/2019

By: Behnam Jahangiri, Hamed Majidifard, James Meister, and William G. Buttlar

This study investigates the performance of eighteen different dense-graded asphalt mixtures paved in Missouri. The sections contain a wide range of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS), and different types of additives. The large number of sections investigated and the associated breadth of asphalt mixtures tested provided a robust data set to

Published: 11/26/2018

By: Hamed Majidifard, Behnam Jahangiri, William G. Buttlar, Amir H. Alavi

This paper presents innovative machine learning methods called gene expression programming (GEP) and hybrid artificial neural network/simulated annealing (ANN/SA) to predict the fracture energy of asphalt mixture specimens. The GEP and ANN/SA models are developed using an experimental database including a number of disk-shaped compact tension (DC(T)) test results for fracture energy. The fracture energy

Published: 11/21/2016

By: Behzad Behnia, William G. Buttlar, Henrique Reis

The present work for the first time reports observations and modeling to characterize three-dimensional spiral-shaped fracture patterns in a bi-axially stressed layer of asphalt material bonded to an aluminum substrate. Five different asphalt materials with different fracture characteristics are investigated. A logarithmic spiral model was found to mathematically represent the 3D helix-shaped cracks observed. A

Published: 04/26/2016

By: Megan E. McGovern, William G. Buttlar, Henrique Reis

Because in the field asphalt concrete acoustic properties (i.e., velocities and corresponding attenuations) are unknown, a modified version of the non-collinear wave mixing method is proposed to evaluate oxidative aging levels. Longitudinal transducers mounted on angle wedges are employed to launch subsurface dilatational waves to allow evaluation when there is only access to one side

Published: 05/07/2017

By: Megan E. McGovern, William G. Buttlar, and Henrique Reis

Except for the relatively small zones within pavements that are subjected to loadings, the primary challenge in asphalt concrete (AC) pavement design and maintenance is to prevent and/or control environmentally induced distresses. Distresses, including block and thermal cracking, and possibly raveling of construction joints, tend to accelerate with time; as a result, it is critical