Pavement Materials from Waste Tires: from Research to Practice

Biography:
Dr. Zhanping You earned his Ph.D. in Civil Engineering from the University of Illinois at Urbana - Champaign in 2003. After serving years of faculty positions in the Department of Civil and Environmental Engineering at Michigan Technological University, he was promoted to Professor in 2014 and earned a Distinguished Professorship in 2019.
Dr. You has completed research projects related to road materials, pavement engineering, and sustainable building materials. His contribution to pavement and materials research has led to journal articles, book chapters, and advances in engineering practice. He has led research projects from engineering practice of roads to pavement science with funding from federal, state, and local agencies.
Dr. You has received numerous recognitions. He was awarded the U.S. Department of Transportation’s Dwight David Eisenhower Transportation Fellowship in 2001. In both 2004 and 2005, he was awarded the Dwight David Eisenhower Transportation Faculty Fellowship. He earned the prestigious Michigan Tech Research Award in 2019 and University Distinguished Professorship. He was named as Fellow of ASCE and Fellow of the International Association of Advanced Materials in 2020. Dr. You served as the Chair of ASCE Engineering Mechanics Institute’s Pavements Committee and CI’s Bituminous Materials Committee. He is also the guest editor for other journals outside of ASCE.

Abstract:
Stockpiles of waste tires pose concerns of potential contamination of local groundwater and fire risk from the massive amounts of tires. To properly use the waste tires, tire rubber recycled from waste tires has been used in the pavement industry for decades. However, the function of such recycled tire rubber in the internal structure of asphalt mixtures was not fully understood. This study attempted to establish discrete element models (DEM) to investigate the strength, skeleton structures, and stress distribution of rubber modified asphalt mixtures. New modeling procedures were developed to incorporate coarse aggregate shapes and rubber particles. Indirect tensile strength (ITS) of specimens with rubber materials was tested in the laboratory and also modeled in simulations. The internal-structure and stress distribution of specimens with different rubber contents were analyzed. The gap gradation was proved to have a functional capacity of accommodating fine aggregates and rubber particles, all while forming a coarse aggregate skeleton. The research team also expanded the research work from models and lab work to field pilot projects. Quite a few pilot projects that using recycled tire rubber were constructed as asphalt pavements in Michigan (MI). A recent project used a reacted rubber in Kalamazoo, MI and the other project used a pre-swollen rubber in Dickinson, MI. In general, the test results from the laboratory were favorable regarding moisture damage resistance, low temperature cracking resistance, and noise reduction. In the Kalamazoo project, it was estimated that approximately 5,300 passenger tires been recycled to the road that would otherwise be disposed of in a landfill. In the Dickinson project, the amount of recycled tire is equivalent to about 3,500 passenger tires.