Janson, Austin2023-05-122023-05-122023-03https://hdl.handle.net/11299/254112University of Minnesota M.S. thesis. March 2023. Major: Dentistry. Advisor: Christine Blue. 1 computer file (PDF); iii, 105 pages.Distresses such as joint faulting, cracks, and slab shattering can cause premature failure concrete pavements. To prevent these distresses, a few strategies can be employed. The first is to make sure the concrete itself is strong and durable. This can be accomplished through the Performance Engineered Mixtures (PEM) method. The PEM method aims to produce concrete with freeze-thaw durability, minimal shrinkage, good workability, and high strength. A large part of the PEM method is optimizing the aggregate blend for the perfect balance of workability, finishability, and density. Another strategy for preventing pavement distresses is to increase joint load transfer to reduce joint faulting. In standard concrete pavements, dowel bars are used at the joints to increase load transfer efficiency (LTE). However, for thin and ultra-thin pavements (less than 7 inches thick), dowel bars are not recommended for use. One of the probable solutions is to use structural or macro fibers in place of dowel bars. Synthetic macro fibers are used most of the time in fiber reinforced concrete (FRC). But all synthetic fibers are not created equally. The objective of this research is to study individual fibers and discover which properties of the fibers make them suitable for pavement application.The research was split into two stages. The first stage of the research involved making FRC concrete and testing it to determine the effects of different fibers on post-crack residual strength. The materials used in this study include three types of coarse aggregates, one fine aggregate, two types of fiber, one type of cement, fly ash, and admixtures. Fiber dosages (4 pounds per cubic yard (pcy) and 7.6 pcy) were considered in terms of volume fraction. The second stage of the research involved making concrete with varying properties and testing several different fibers via single fiber pullout testing. The materials used for this stage are the same as the first, with an additional three fiber types being used. The fiber dosage and type used in this study had significant influence on the hardened concrete post-crack behavior. The influence of fiber dosages and type on the flexural toughness was apparent. The average RSR for all the mixtures containing Fiber 1 is 31.1%, whereas the mixes containing Fiber 2 have an RSR of 40.7%. Fiber 1 is a smooth, twisted fiber and Fiber 2 is a stiffer, embossed fiber with a larger effective diameter. In the single fiber pullout testing, for Fiber 2, the average peak load is 57.3 lbs., and the toughness is 23.5 lb.-in. This is a significant increase over the Fiber 1 results where the average peak load is 7.2 lbs., and the toughness is 2.4 lb.-in. The results from the single fiber testing correlate well with FRC results, suggesting that single fiber pullout testing can be used in the future to further improve upon existing fibers.enThesis or Dissertation