In the United States, there are over 2.6 million miles of paved roads 94.6% of which have an asphalt concrete surface, representing a $30 billion annual investment. Premature fracturing of asphalt overlays poses a significant economic and environmental burden to society and can reduce the safety of our nation?s highway and airfield pavement infrastructure. The proposed partnership between university and industry in this GOALI study will lead to the development of advanced pavement rehabilitation systems (thin, bonded overlays) that are recyclable, sustainable, and provide a safe riding surface. The proposed work plan will utilize a hybrid approach, involving advanced laboratory testing and instrumentation, development of new damage models, simulation of pavement systems, and calibration of models to field performance. This project will also improve how digital imaging can be used to understand fracture behavior in complex, layered, composite infrastructure material systems.
Besides the aforementioned advancement in discovery and understanding, the broader impacts of the proposed project are: the promotion of teaching, training, and learning, through incorporation of research results in university courses; broadened participation in research by underrepresented groups through Minority Outreach Program and the Worldwide Youth in Science and Engineering Program; and; broad dissemination of research results in journals, and through conference presentations, and workshops. The benefits of the proposed research to society include: a more sustainable approach to pavement maintenance; reduced life cycle costs, and; improved highway safety. Through partnership with industry, the new techniques will be validated against field projects and transferred to practitioners through regional workshops.
A drive across the US interstate, state and local roadways is indeed an unparalleled experience from a worldwide perspective; however, increasing traffic, challenging environmental conditions, and the tightening of transportation funding has rendered many US roadways in sub-par condition. This project sought to use cutting-edge modeling and measurement tools to advance the science behind new, weather- and traffic-resistant road surfacing and re-surfacing materials. Since nearly 95% of all pavement surfaces in the US are composed of asphalt concrete, this project focused on the physical properties of asphalt concrete, particularly it's resistance to various forms of cracking and it's bonding characteristics or adhesion to existing, underlying pavement layers. Because asphalt concrete is composed of a strong aggregate (crushed rock, gravel and sand) skeleton, bonded together with asphalt cement (derived as a by-product during the refining of crude petroleum), detailed study of cracking mechanisms under loading was carried out using an advanced digital camera based imaging system, along with custom designed software to extract information about crack formation and propagation. This information was then fed into a custom-designed pavement cracking simulation model, which was used to develop more crack-resistant pavement surface materials. A side benefit of the research was the ability to develop more eco-friendly materials, such as those containing higher amounts of recycled materials and energy saving construction methods. Results from the research is also transferable to the Aerospace, Material Science, and Bio-Engineering fields of study and practice. By collaborating with an industry partner, Road Science LLC, results were transferred to practice during the course of the research. Pavements across the Midwest in states such as Oklahoma, Kansas, Missouri, Illinois, Indiana, Ohio, and Pennsylvania were constructed during the course of the study, benefitting from the aforementioned advances in science made possible through this NSF grant. The collaboration with industry was made possible by the NSF GOALI (Grant Opportunities for Academic Liaison with Industry) program.
