UW Modified Asphalt Research Center

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Sustainable Asphalt Pavements: Technologies, Knowledge Gaps and Opportunities
Timothy Miller and Hussain Bahia

This investigation sought to increase awareness about gaps in technology regarding asphalt pavement sustainability. It presents initial sustainability challenges; available methods, models and tools to estimate pavement sustainability; the energy, emissions and environmental impact of current and promising asphalt technologies; and thoughts on next steps for research required in these areas.

2009 Modified Asphalt Research Center white paper
Effects of Temperature and Compaction Effort on Field and Lab Densification of HMA
Robert Schmitt, Carl Johnson, Andrew Hanz, and Hussain Bahia

This study evaluated the effect of compaction effort and temperature on densification of HMA in the field and in the lab, investigating the minimum limiting temperatures at which 92% Gmm field density can be achieved with commonly used compaction effort. The results, in general, point out the possibility of optimizing the compaction process by understanding the role of temperature and pressure, which are mixture-type specific.

2009 Annual Meeting of the Association of Asphalt Paving Technologists
Abstract · Contact AAPT for the full paper

Evaluation of Rheological Properties of Binders in RAP without Extraction and Recovery
Emil Bautista, Salvatore Mangiafico, and Hussain Bahia

The aim of this research project was to develop a protocol to estimate the low temperature rheological properties of binders in the RAP without the damaging effects of solvent extractions. The ultimate goal was to answer the question of when does the change in PG grade of fresh binder becomes a requirement in a mixture using RAP.

2009 Annual Meeting of the Transportation Research Board
Abstract · Poster · Contact TRB for the full paper
Storage Stability and Effect of Mineral Surface on Polyphosphoric Acid (PPA) Modified Asphalt Binders
Codrin Daranga, Cristian Clopotel, Adekunle Mofolasayo, and Hussain Bahia

In this study, two asphalt binders were modified with polyphosphoric acid and mixed with two fillers. By varying testing parameters, the changes in rheological behavior of the liquid binder during storage were analyzed. In addition, the effect of contact with mineral surface was investigated to reflect the possible interactions that could take place in asphaltic mixtures during processing and handling at high temperature.

2009 Annual Meeting of the Transportation Research Board
Abstract · Contact TRB for the full paper

Conceptual Phenomenological Model for Interaction of Asphalt Binders with Mineral Fillers
Ahmed Faheem and Hussain Bahia

This study provided a conceptual model for understanding the mechanism by which the filler stiffens the asphalt mastic. The model hypothesizes that the mastic complex stiffness follows two phases depending on the volume concentration of the filler; a diluted phase and a concentrated phase.

2009 Annual Meeting of the Association of Asphalt Paving Technologists
Abstract · Presentation · Contact AAPT for the full paper

Characterizing Fatigue of Asphalt Binders Using Viscoelastic Continuum Damage Mechanics
Haifang Wen and Hussain Bahia

This paper studied the application of viscoelastic continuum damage mechanics which has been successfully applied to HMA, to test results of asphalt binders in the shear mode under various loading conditions. The results indicated that VECD can be effectively applicable to asphalt binders, which presents a good potential to characterize asphalt binder and predict its contribution to fatigue resistance using a fundamental approach that parallels some of the advanced work carried on asphalt mixtures.

2009 Annual Meeting of the Transportation Research Board
Abstract · Contact TRB for the full paper

Practical Application of Viscoelastic Continuum Damage Theory to Asphalt Binder Fatigue Characterization
Carl Johnson, Haifang Wen, and Hussain Bahia

The ability of the binder phase of an asphalt mixture to resist fatigue damage can have a profound effect on the service life of an asphalt pavement. This paper presents a new attempt to use existing testing procedures (the Dynamic Shear Rheometer) to estimate fatigue resistance in a relatively short period of time. The data collected in the new test can be used for a fundamental analysis procedure based on the Viscoelastic Continuum Damage theory to estimate fatigue of binders under varying levels of traffic and pavement conditions.

2009 Annual Meeting of the Association of Asphalt Paving Technologists
Abstract · Contact AAPT for the full paper

Effect of Mineral Filler on Damage Resistance Characteristics of Asphalt Binders
Ahmed Faheem, Haifang Wen, Lawrence Stephenson, and Hussain Bahia

Numerous studies have indicated that the addition of mineral filler to an asphalt binder increases the stiffness of the binder. In this study, the effects of filler content and type on the damage resistance of mastics (filler-binder system) were investigated. The mastics and binders were tested to evaluate the effects of type and content of the fillers on fatigue and rutting performance of mastics.

2008 Annual Meeting of the Association of Asphalt Paving Technologists
Abstract · Contact AAPT for the full paper

Advanced Methods for Quantifying Emulsion Setting and Adhesion to Aggregates
Andrew Hanz, Zelalem Arega, and Hussain Bahia

An important emulsion property consideration in chip seal applications is the time required for the development of adequate binder properties. This paper focuses on using two test methods to quantify the time dependence of emulsion setting in terms of critical performance properties. The objective was to introduce more precise and scientific tests for better understanding of emulsion setting and its dependence on chemical and physical factors.

2008 International Symposium on Asphalt Emulsion Technology
Full paper · Presentation
Rheological Evaluation of Emulsion Residues Recovered Using Newly Proposed Evaporative Techniques
Andrew Hanz, Zelalem Arega, and Hussain Bahia

Increasing use of emulsified asphalts and the introduction of modified emulsions to the market has resulted in the need for development of a new residue recovery method. This study evaluated a proposed ASTM evaporative recovery procedure through measuring performance related binder properties using common rheological test methods to monitor the change in performance of the residue over recovery time.

2009 Annual Meeting of the Transportation Research Board
Abstract · Poster · Contact TRB for the full paper