UHPC Joint Fill Construction Problems and Solutions on the Pulaski Skyway

The redecking of the Pulaski Skyway is the largest implementation of ultra-high performance concrete (UHPC) in North America to date. Approximately 90,000 m² (1 million ft²) of deck was replaced with precast concrete panels connected with field-placed UHPC, using a total volume of more than 5,000 cubic yards (3,800 cubic meters) of UHPC. The construction of the new deck took place over the course of four years in a temperate climate with hot summers and cold winters. The very large quantity of deck, the large volumes of field-placed UHPC, and multiple years of construction with all possible weather and temperature conditions created challenges to successful UHPC placement. This paper discusses the types of problems that arose and the solutions that were developed during the course of the redecking construction project. The problems included placement issues related to pumping, fiber segregation issues deriving from low ambient temperature, cracking due to early age loading, and underfilled pockets and joints due to leaking or blown-out forms. The distinct issues encountered are set out in detail, along with the solutions and the methods that were employed to find the solutions, with a discussion on the reasoning behind the selection made in each case. The information presented is intended to serve as a resource for engineers and construction inspectors undertaking UHPC joint fill projects, providing substantive explanations of the sort of UHPC construction problems that can arise and examples of means utilized to address them.