Master of Science in Engineering, University of Akron, 2022, Civil Engineering

Ohio Department of Transportation (ODOT) specifications are followed by most of the Local Public Agencies (LPAs) in the design and the construction of the mixtures used in low-volume traffic roads. For low-volume traffic roads, asphalt overlays are based on Marshall mix design method, and Type 1 surface mixes that are designed with PG64-22 asphalt binder depending on the current ODOT mix design specifications. Alternatively, several LPAs use Item 404 which is a mixture that was used by ODOT for decades in low-volume traffic roads before getting removed in 2002 and reintroduced again in 2008 with some modifications. Another modifications and changes have been made on Item 404 till it reached its current characteristics and specifications in which is known as Item 404LVT (Low Volume Traffic) that was published in Flexible Pavements of Ohio 2015 (FPO 2015). The main goal of this research is to optimize Item 404LVT specifications to produce more cost-effective, longer-lasting low-volume traffic roads by using a comprehensive laboratory testing plan for multiple Item 404LVT mixtures. In addition, field evaluations were conducted in several counties where pavements were constructed using Item 404LVT mixtures in order to supplement the findings of the different laboratory tests.

Doctor of Philosophy (PhD), Ohio University, 2017, Civil Engineering (Engineering and Technology)

Low-temperature cracking is a major pavement distress for asphalt pavements in most northern parts of the United States and other colder regions of the world. Pavements exposed to cold conditions are subjected to thermal stresses which can result in cracking when the induced stresses exceed the tensile strength. Local governments and road agencies spend large sums of money annually to repair defects in pavements caused by low-temperature cracking. Researchers need straightforward and routine test devices to characterize asphalt mixture's low-temperature performance in the laboratory. These tools are also required to design pavements that can perform satisfactorily in cold temperatures, and for the prediction of frequency and magnitude of cracks developed in asphalt pavements. The low-temperature performance characteristics of asphalt mixtures can be grouped into two broad components. There is the stiffness and thermal contraction component which accounts for the magnitude of strains or stresses induced in the mixture during cooling. The strength or fracture toughness component accounts for the ability of the mixture to resist the induced stresses and to prevent cracking. The main objective of this dissertation was to develop straightforward and routine tests devices for low-temperature characterization that would account for these two components of mixture's low-temperature performance. The Ohio Coefficient of Thermal Contraction (CTC) device developed as part of this dissertation was shown to produce repeatable test data. Asphalt mixture thermal strains recorded from the CTC device fitted the Bahia-Anderson CTC mathematical model for mixtures with a coefficient of determination (R2) greater than 0.999. Mixture properties such as binder grade, binder content, aging and the inclusion of recycled materials [Recycled Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS)] resulted in a significant change in the CTC. Asphalt mixtures prepared with two aggrega (open full item for complete abstract)