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Title: Innovative UHPC Mixing and Placing Techniques for Repair of Three Illinois Bridges

Author(s): McDonagh

Publication: Web Session

Volume: ws_S22_McDonagh2.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
Kane County, Illinois repaired three bridges in 2020 using ultra-high-performance concrete (UHPC), a material known for its exceptional durability. The UHPC supplier, Steelike, introduced multiple innovative techniques that allowed helped accelerate portions of the contractor’s work and reduce the contractor’s costs. Innovative mixing techniques included mixing the UHPC in ready-mix trucks, which allowed the UHPC placements to proceed faster than typical rates with traditional UHPC mixers. Additionally, the UHPC was mixed offsite for one project with over 1.5 hours between mixing and final discharge, providing greater flexibility for mixing location and placement timing. Innovative placement techniques included directly discharging the UHPC from the ready-mix truck onto the bridge deck in front of the screed for a UHPC overlay. This eliminated buggies commonly used to transport UHPC and reduced labor and UHPC waste. The UHPC overlay was also successfully cured without plastic sheeting, eliminating the risk of deep impressions in the overlay surface from the sheeting or sheeting hold downs that have been seen on other projects. Additional innovative placement techniques for two projects repairing keyways between adjacent precast beams included flush forming the new UHPC connections. Flush forming was successfully performed without trapping air in the top layer – the reason why deck-level UHPC connections typically require overfilling and grinding – due to a unique process pioneered by Steelike.