Browsing by Subject "Deterioration"
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Item Deterioration of Mixed Rebar and Fiber-Reinforced Concrete Bridge Decks(Minnesota Department of Transportation, 2019-02) Treat, Corin; Dymond, Benjamin Z.Between 1973 and 1989, approximately 600 bridge decks were constructed in Minnesota with a top layer of epoxy-coated rebar and a bottom layer of uncoated rebar (i.e., mixed rebar deck) to potentially reduce corrosion in the top layer of rebar. In the last five years, at least 20 bridge decks were constructed with polypropylene fibers in the concrete mix to reduce the width and amount of cracking. This project investigated how mixed rebar or polypropylene fibers affected the rate of deterioration in bridge decks (e.g., spalling of underside of deck concrete or unsound concrete on the top wearing surface) compared to control structure decks of approximately the same age. Visual inspections were conducted on certain bridges to compare the visual degradation of the mixed rebar and fiber-reinforced decks with their control structure decks. The results were subdivided to indicate how the superstructure type, average daily traffic, route type, and wearing surface crack density affected the condition ratings and rate of deterioration. The mixed rebar decks reached worse condition states than the control structures when comparing the condition of the underside of the deck; steel superstructures had the largest negative affect on the deterioration. Recommendations included: create an inspection rating element for mixed rebar decks that quantifies the underside of deck crack density, use a robust crack sealing method on mixed rebar decks when they have been at NBE Element #12 CS2 for approximately 7 years, and continue comparing fiber-reinforced decks to control structure decks to analyze the deterioration over time.Item The Impacts of Deferred Maintenance in Minnesota(Minnesota Department of Transportation, 2022-04) Fonseca-Sarmiento, Camila; Zeerak, Raihana; Jiang, Haiyue; Zhao, JerryThe roadway system is critical to social development, economic growth, and the overall quality of life. In the U.S., the condition of highways and roads is being compromised due to several reasons including age deterioration, rising costs of construction, and a decline in funding. Similarly, in Minnesota, the majority of pavements are aging and in need of significant maintenance or reconstruction, but there is an expected deficit of $17.7 billion for state roads over the next 20 years. At the local level, pavement conditions along state-aid roads and county, city, and township roads are anticipated to deteriorate significantly based on current funding levels. In addition, significant budgetary impacts on maintenance spending are expected due to the COVID-19 pandemic. Given these budget limitations, agencies often postpone planned maintenance to make funding available for other transportation purposes, but the deferred maintenance will negatively affect asset life, leading to higher future maintenance costs and lower roadway safety. This research analyzes spatial patterns of maintenance expenditures across localities in Minnesota, explores how fiscal conditions affect maintenance expenditures, and examines roadway maintenance decision-making across localities.Item Innovative Materials and Advanced Technologies for a Sustainable Pavement Infrastructure(Minnesota Department of Transportation, 2021-06) Le, Jia-Liang; Marasteanu, Mihai; Zanko, Lawrence M.; Matias de Oliveira, Jhenyffer; Calhoon, Thomas; Turos, Mugurel; Stricherz, Tyler; Hopstock, David M.; Hegg, VernIt is widely acknowledged that early detection of material damage and timely rehabilitation can lead to a significant reduction in the life-cycle cost of asphalt pavements. This research investigates the capabilities of damage detection and healing of graphite nanoplatelet (GNP)-taconite modified asphalt materials. The first part of the research is concerned with the application of GNP-taconite modified asphalt materials for damage detection using electrical conductivity. It is shown that, as compared to conventional asphalt materials, the GNP-taconite modified asphalt materials exhibit an improved electrical conductivity due to the electron hopping mechanism. Based on the mathematical analogy between the elastostatic field and the electrostatic field, a theoretical model is derived to relate the change of electrical conductivity to the damage extent of the material. Although, in principle, the material damage can be accessed using the electrical conductivity, the practical application of this method is complicated by the fact that the conductivity is influenced by the moisture content. The second part of the research investigates the damage healing capability of GNP-taconite modified asphalt materials heated by microwave. GNP-taconite modified asphalt materials can effectively absorb the heat generated by the microwave, and the rising temperature can effectively heal the microcracks in the binder. This damage-healing mechanism is verified by a set of semi-circular beam tests. Finally, microwave heating technology is applied to the tack coat system. It is shown that, with microwave heating, the GNP-taconite modified asphalt material can effectively improve the bond strength of the interface of the tack coat system.