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Item Exploration of UHPC applications for Montana bridges(Montana State University - Bozeman, College of Engineering, 2023) Starke, James Gerald; Chairperson, Graduate Committee: Kirsten MattesonThe following research project explores bridge applications of ultra-high performance concrete (UHPC). Bridge deterioration is a problem across Montana and UHPC overlays and patching/repairing have been found to be viable alternatives to bridge replacement. The current study began with a literature review on research, specifications, and implementation projects of UHPC bridge deck overlays. A report from FHWA was highlighted that summarized the results of previous overlay and repair projects, and developed their own recommendations. A material-level evaluation was performed on three UHPC mixes, primarily focusing on workability, compressive strength, tensile strength, and tension and shear bond strengths. All three UHPCs exhibited adequate behavior and the resultant properties were above recommendations from ACI for concrete repair and overlay applications. Based on the material-level evaluation results, a thixotropic version of Ductal was chosen for subsequent structural testing. Five slab test specimens were designed and constructed to model a deck section from an existing bridge in Montana. The testing and specimens were designed to determine the effects that including a UHPC overlay, overlay thickness, and substrate concrete strength have on the ultimate moment capacity. The slabs consisted of one control slab, two slabs with varying UHPC overlay depths, one with weak substrate concrete, and one tested to emulate a negative moment region on a bridge deck. The testing demonstrated that including a UHPC overlay increased the ultimate moment capacity of the slabs, even with a weak substrate concrete, but cause the slabs to fail in shear rather than concrete crushing. Additionally, the results imply that a weak deck strengthened with a thin UHPC overlay will respond similarly to a deck composed of much stronger normal concrete. The tensile capacity of the UHPC plays a large role in the overall strength and stiffness of a slab subjected to a negative moment and the tensile strength should be included in capacity calculations, as recommended by FHWA. Overall, the results are promising and shed light on how a UHPC overlay may contribute to the overall strength of an existing bridge deck if implemented in a future overlay project in Montana.Item Feasibility of non-proprietary Ultra-High Performance Concrete (UHPC) for use in highway bridges in Montana: phase III implementation(Montana State University - Bozeman, College of Engineering, 2022) Hendricks, Elias Michel; Chairperson, Graduate Committee: Michael BerryUltra-high performance concrete (UHPC) has mechanical and durability properties that far exceed those of conventional concrete. However, using UHPC in conventional concrete applications has been cost prohibitive, with commercially available/proprietary mixes costing approximately 30 times more than conventional concrete. Previous research conducted at MSU developed a nonproprietary UHPC mix design (MT-UHPC) that is significantly less expensive than commercially available mixes and is made with materials readily available in Montana. The focus of the research discussed herein was on the field implementation of MT-UHPC. Specifically, MT-UHPC was used in all field-cast joints on two bridges spanning Trail Creek on Highway 43 outside of Wisdom, MT. This project began with an extensive literature review focused on previous field applications of UHPC. Subsequently, implementation research was performed with the intent of filling several research gaps related to the field application of MT-UHPC. This research investigated the effects that mixing process, batch size, and temperature have on the performance of MT-UHPC. It also developed maturity curves to be used in estimating the early strength gain of MT-UHPC. Trial batches were then conducted on site and placed into joint mockups to confirm and improve the construction methods to be used on the actual bridge project. In this exercise MT-UHPC was mixed using the same methods and under the same environmental conditions expected on the day of construction. MTUHPC was then used in the Trail Creek bridges to connect the precast concrete bridge elements. Overall, this project was a successful demonstration of using a nonproprietary UHPC in field-cast joints for an accelerated bridge construction (ABC) project. All placed UHPC had adequate flows, gained strength quickly, and reached the required minimum compressive strengths. This was accomplished despite an accelerated construction schedule, and despite mixing and placing the material in the field under varied environmental conditions.