Pavements/Materials Engineering at the University of Nevada, Reno is a nationally recognized teaching, research, and training program in the College of Engineering. It includes an undergraduate and graduate teaching program and the Western Regional Superpave Center (WRSC, www.wrsc.unr.edu).
Dr. Peter Sebaaly, Professor of Civil Engineering and director of the program, has over twenty years of experience in the area of pavement design and materials and vehicle pavement interaction. Dr. Elie Hajj is an Assistant Professor of Civil Engineering, has several years of experience in asphalt binders and mixtures testing and vehicle pavement interaction.
Federal state, and corporate sponsors provide funding that employs undergraduate students, graduate students, and professional researchers to complete problem solving research. Research has focused on the laboratory and field evaluation of modified asphalt binders and asphalt mixtures including recycled asphalt pavements and warm mix asphalts, the water sensitivity of asphalt mixtures, pavement instrumentation, pavement performance studies, and rehabilitation and maintenance design procedures.
We offer a B.S. in Civil Engineering degree with Pavements/Materials emphasis and a graduate program (M.S. and Ph.D.) in Pavements/Materials engineering. Our graduates obtain an education that serves as a foundation for successful careers in pavements engineering practice or academia.
Peter Sebaaly, Ph.D., P.E.
Ellie Hajj, Ph.D.
Evaluation of Construction Techniques for Longitudinal Joints in HMA Pavements
Hot mixed asphalt (HMA) pavements are normally constructed with multiple passes of the paver. Typically, one lane is laid-down with each pass. Consequently, a longitudinal construction joint is formed between the constructed lanes. A low density at the longitudinal joint would result in water penetrating into the HMA layer and damaging the HMA mix and the supporting layers. The water damage usually causes premature failure of the flexible pavement. One way to avoid such failures is to construct a dense longitudinal joint that would prevent the intrusion of water. The overall objective of this research was to establish the needed knowledge base for the development and implementation of a longitudinal joint specification for the Nevada Department of Transportation (NDOT). A field-testing program was carried out to evaluate the effectiveness of the various joint geometries and compaction techniques in increasing the joint density and providing improved performance.
2007 Conditions of the Longitudinal Joint of the Cut Edge with Tack Coat,
Rolling Pattern I section on US 395 Washoe Valley Project.
2007 Conditions of the Longitudinal Joint of the Edge Restrain,
Rolling Pattern II section on US 95 Las Vegas Project.
Design System for HMA Containing a High Percentage of RAP Material
Reclaimed asphalt pavement (RAP) is generated by cold milling, heating/softening and removal of the existing aged asphalt pavement, full depth removal, or plant waste hot mix asphalt (HMA) materials. The interest in the use of RAP has increased dramatically since the recent price increases in crude oil and energy in general. Therefore the use of RAP materials in HMA can be highly beneficial from both the economical and long-term performance aspects if the appropriate testing and analysis procedures are used to design the final mixtures. The overall objective of this research effort is to develop testing and analysis procedures that can be effectively used to evaluate RAP materials and optimize the performance of HMA mixtures containing RAP materials. The research effort will cover the various aspects of the design process starting with the evaluation of the RAP materials (binders and mixtures) through the mix design process and the performance evaluation of the final HMA mixture containing RAP materials.
Warm Mix Asphalts
Asphalt pavements make up 95% of the paved roads in the US. The production and construction of asphalt mixtures are conducted at extremely elevated temperatures which consumes a significant amount of fuel and generates high dust and emissions. Typical asphalt mixtures are produced by heating the aggregates and asphalt binders at 325oF and laying the mix down on the road at 300oF. This process is known as the Hot Mix Asphalt (HMA). The Pavements/Materials Program in the Department of Civil and Environmental Engineering is a member of a national group that is working to develop a technology by which asphalt mixtures can be produced and constructed at lower temperatures. This process is called Warm Mix Asphalt (WMA). The WMA technology is expected to reduce the production temperature to around 250oF and the construction temperature to around 200oF. These reductions in temperatures are expected to reduce CO2, CO, and NOX emissions by some 35%, reduce dust generation by 90%, and reduce fuel usage by around 35%. The overall objective of this research effort is to gain an understanding of the effects of commercially available warm mix additives on the performance of the asphalt binder and mixture and mixture workability. This understanding will allow for optimization of mixture design and construction practices for application of warm mix technology to the field. Optimized practices will be applied in field trials and evaluated/refined through monitoring of pavement performance. Overall the work of the Pavements/Materials Program is expected to generate positive impacts on highway workers safety, the economy, and the environment.
Classification by temperature range, temperatures, and fuel usage are approximations. (FHWA Report PL-08-007, WMA European Practice Report)
Impact of Hydrated Lime on Performance of Asphalt Mixtures
The purpose of this project is to quantify expected increases in pavement life from adding lime to asphalt, based on extensive laboratory testing of multiple lime-asphalt mixtures. This project differs from previous studies in several respects. First, because lime is used in asphalt primarily for antistripping benefits, previous studies rarely quantify lime’s other performance benefits. Second, because testing is typically performed on only the asphalt mix being considered for a project, and only as necessary to satisfy specifications, typical studies do not capture the full range of failure modes and environmental stresses. Furthermore, once specifications are met, test results are rarely translated into pavement performance characteristics. This project, by contrast, will evaluate five asphalt mixtures with the most widely accepted laboratory tests for the following modes of pavement failure: moisture damage, fatigue cracking, permanent deformation, thermal cracking, and oxidative aging.
With these tests, the impact of lime and liquid additives on the mechanical properties and performance of HMA mixtures will be estimated, in terms of increases in pavement life. Changes in pavement life and performance will also be translated into changes in the life cycle cost of HMA pavements.
In evaluating a student's application to the pavement and materials engineering graduate program, the faculty will consider all aspects of the student's credentials. This includes academic performance in their respective past programs, scores on entrance examinations (GRE and TOEFL, if applicable), references, and the applicant's stated goals.
Financial aid available to students ranges from full or partial Teaching or Research Assistantships. Most graduate students are supported by assistantships. Awards are made on the basis of scholarship and promise for outstanding achievement. The applicant's grade point average, score on the GRE and letters of recommendation are the primary means used for selecting new students to receive financial aid.
Department of Civil & Environmental Engineering
Pavements Engineering Program
University of Nevada, Reno/0258
Reno, NV 89557-0258
Phone: (775) 784-6937
Fax: (775) 784-1390