An-Atomic-Force-Microscope-based-analysis-of-asphalt-Hossain-and-Rashid

2016 Oklahoma Transportation Research Day An Atomic Force Microscope‐based Nanomechanistic Properties of Reclaimed Automobile Tires Modified Asphaltic Pavements Zahid Hossain1 and Feroze Rashid2 Assistant Professor of Civil Engineering, Arkansas State University, PO Box 1740, State University, AR 72467, Phone: (870) 680 4299; E-mail: mhossain@astate.edu Graduate Research Assistant, Arkansas State University, PO Box 1740, State University, AR 72467, USA, Phone: (870) 680 4299; E-mail: amferoze.rashid@smail.astate.edu ABSTRACT: Over 5.2 million tons of scrapped tires are produced each year in the United States Disposal of this huge amount of scrapped tires has become a serious environmental issue and economical burden to the taxpayers In recent years, the use scrapped tire in the form of Ground Tire Rubber (GTR) in road construction projects has been explored as it has potential to improve asphalt’s performance from stiffness, resilience and shock absorbance perspectives Some researchers have started using the atomic force microscope (AFM)-based nanoindentation technique to characterize pavement materials to observe behavior of the materials at a molecular level In this study, the PeakForce Quantitative Nanomechanical Mapping (PFQNM™) mode has been employed to find phase contrast and nanomechanistic properties and morphology of GTRmodified binders A performance grade (PG 64-22) binder modified with two different grades (Mesh #30 and Mesh #40) of GTRs has been evaluated in this study Surface Characterization (e.g., topography) and nanomechanical properties such as adhesion, hardness, and DMT (Derjaguin, Muller, and Toporov) modulus for each blend have been quantified Each sample was scanned at three different areas to ascertain the repeatability of test results Phase-contrast imaging in the PGQNM™ was found to be powerful method in surface characterization Two distinct phases, namely, Catana and Peri-phase, were observed in GTR-modified samples Two other phases, namely, Sol-phase and Perpetua-phase were also observed in some samples The DMT moduli of GTR-modified binders were found to be in a close range It was observed that modification of asphalt by GTR considerably changes the mechanistic properties of the base binder The findings of this study are expected to be beneficial for pavement professionals and policy makers toward sustainable uses of waste automobile tires in road construction projects