Large-scale Implementation of Semi-proprietary UHPC with Virgin and Recycled Fibers for Full Precast Bridge Columns

The use of ultra-high performance concrete (UHPC) is currently expanding worldwide from bridge deck joints and overlays or small architectural applications to full components and larger applications. In the US, the Federal Highway Administration (FHWA) is developing mega bridge girders up to 300-ft spans (El[1]Helou et al. 2022) while also developing the first AASHTO design guidelines for UHPC bridge applications. Another large initiative funded by PCI developed non-proprietary UHPC mixes for precast/prestressed girders (Tadros et al. 2022). Such efforts will help expand the UHPC market and encourage researchers to look at other applications such as full UHPC columns and their applications for precast construction especially in seismic areas. To contribute towards filling the general knowledge gap on columns, the team at UNR has completed several projects over past 5 years (e.g. Aboukifa and Moustafa 2022; Aboukifa et al. 2020, and Subedi et al. 2019) that focused mostly on fundamental axial behavior of UHPC columns and accelerated bridge construction (ABC) connections. However, more work is still needed to scale-up columns construction and investigate structural and seismic behavior of full precast UHPC bridge columns and different ABC column-to-footing connections. Seismic columns are of particular interest since UHPC has been previously considered for retrofit applications and previous studies (e.g. Aboukifa et al. 2020) demonstrated UHPC seismic columns as viable candidates for future resilient and state-classified important bridges. Meanwhile, with the increased interest in larger and full structural UHPC applications, economy and sustainability become of paramount significance. As such, the research team just started working with a major UHPC vendor (Cor-Tuf) to develop semi-proprietary UHPC mixtures with local sand and cement along with recycled steel fibers from landfill tires, which is a major initiative that the team will leverage in this project. If demonstrated and implemented successfully, recycled steel fibers could be the next big leap in the UHPC world. This is because not only a pound of recycled fibers is about 25 cents versus ~2.5 dollars for virgin or manufactured fibers, but also expanding tires recycling and clean landfill operations is of a great environmental benefit. It is noted that the steel industry is among the largest contributors of CO2, making up 8% of the total carbon emissions according to the DOE (2023). Federal agencies like the DOE have created roadmaps to achieve decarbonization by improving material composition and increasing material lifespan (DOE 2023). Thus, one way to contribute to the easement of the carbon footprint associated with UHPC steel fibers is the use of recycled steel wires/fibers from landfill tires. It is noted that while old and worn tires from cars and trucks contribute to increasing waste in landfills, tire recycling can help with clean landfill operations and prevent incinerations that can release toxic pollutants and carbon into the atmosphere. In used tires, 12-21% of the overall tire composition is steel fibers (US Tires 2023). Technology such as pyrolysis and shredding allows used tires to be decomposed, separating the steel fibers (Williams 2013). The steel fibers generated from this process can be recycled and efficiently used as an alternative to manufactured fibers in UHPC to significantly reduce material costs and decrease carbon emissions towards a more sustainable and net zero carbon UHPC. In late 2022, the team started performing several UHPC trials with different types of recycled fibers from landfill tires and then tested a pair of large-scale axial columns to compare the behavior of UHPC with high-end manufactured fibers versus the recycled ones. Figure 1 shows a sample of the different fibers along with pictures and preliminary results from previous UHPC buildings columns tests at UC Berkeley, which the team completed using couple ACI-funded projects. The material tests showed that only tensile behavior of UHPC with recycled fibers might not be at exact same level as virgin manufactured fibers. Nevertheless, at the structural level, since axial columns are less dependent on tensile behavior, the UHPC column with recycled fibers almost outperformed the column with manufactured fibers which is very promising and in turn, motivates this project.

• Record URL:
  https://abc-utc.fiu.edu/research-projects/large-scale-implementation-of-semi-proprietary-uhpc-with-virgin-and-recycled-fibers-for-full-precast-bridge-columns/

Language

• English

Project

• Status: Active
• Funding: $100000
• Contract Numbers:

  69A3551747121

• Sponsor Organizations:

  Accelerated Bridge Construction University Transportation Center (ABC-UTC)

  Florida International University
  10555 W. Flagler Street
  Miami, FL  United States  33174

  Office of the Assistant Secretary for Research and Technology

  University Transportation Centers Program
  Department of Transportation
  Washington, DC  United States  20590
• Performing Organizations:

  University of Nevada, Reno

  Department of Mechanical Engineering
  University of Nevada, Reno--Departm1664 N. Virginia Street, Palmer Engineering Building
  McLean, NV  United States  89557
• Principal Investigators:

  Moustafa, M

• Start Date: 20230530
• Expected Completion Date: 0
• Actual Completion Date: 0
• USDOT Program: University Transportation Centers

Subject/Index Terms

• TRT Terms: Bridge construction; Columns; Fibers; Recycled materials; Ultra high performance concrete
• Subject Areas: Bridges and other structures; Construction; Highways; Materials;

Filing Info

• Accession Number: 01889311
• Record Type: Research project
• Source Agency: Accelerated Bridge Construction University Transportation Center (ABC-UTC)
• Contract Numbers: 69A3551747121
• Files: UTC, RIP
• Created Date: Jul 31 2023 12:08AM