Feasibility of non-proprietary Ultra-High Performance Concrete (UHPC) for use in highway bridges in Montana: phase III implementation

Abstract

Ultra-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.