Rheology Limits for Grout Materials used for Precast Bent Cap Pile Pockets in Hot Weather

While prefabricated bridge elements and systems (PBES) have been used for many years in Florida, The Florida Department of Transportation (FDOT) is currently developing local specifications for PBES to address the Federal Highway Administration (FHWA) Every Day Count (EDC) initiative. The construction on the first designated PBES project in Florida started in 2013 on the US90 between Tallahassee and Quincy. Individual pre-fabricated elements were pieced together and – if needed – grouted to complete the connection details. During the pilot project, grout material was wasted due to the restrictive temperature range and flow rate limitations, specified by the grout manufacturer, or due to inadequate sealing of the connection point. This research aimed to evaluate grouted pile pocket connections to assist the standardization process. Information was gathered through simulating different flow spaces (grout gaps) as well as varying grout consistencies and temperatures, while documenting the flow, final air voids, the temperature development during the hardening process, and final grout strength. For acceptance testing, contractors generally model the structural elements from plywood. Therefore, the pile head for the mockup specimens was made from plywood as well. However, to allow for grout flow observations, the pile pocket was constructed from acrylic glass. PVC pipes were installed on top of the pile-pocket model to aid the filling and ventilation process, simulating ducts used in field construction. Throughout the research, it was determined that the fresh grout temperature, the viscosity of the material and the thickness of the gap between the pile head and the bent cap does not significantly affect the quality of the grout flow and fillability. However, it was found that a tapered roof (7%) inside the pile pocket promotes proper ventilation for the displaced air and helps to avoid air entrapment above the pile head corners. Additionally, it was noted that the current construction tolerances may lead to critical hydration temperatures for massive (high volume-to-surface ratio) grout volumes under hot weather conditions. The research suggests more rigorous construction tolerances to achieve a desired maximum gap size opening of less than 4 in. (100 mm).

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Technical Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 108p

Subject/Index Terms

Filing Info

  • Accession Number: 01629978
  • Record Type: Publication
  • Report/Paper Numbers: FSU Project ID: 037124
  • Contract Numbers: BDV30 TWO 977-16
  • Files: NTL, TRIS, ATRI, USDOT, STATEDOT
  • Created Date: Mar 7 2017 4:25PM