CAMBRIDGE
VIADUCT
PROBLEM:
In 2019, CSC was contacted by SPS New England, Inc. to provide Carbon Fiber Reinforcement to the arches and floor beams supporting the East Cambridge Viaduct bridge to supply additional load capacity to the existing structure. The work consisted of surface preparing the structures, CFRP installation, anchors installation, and acrylic painting.
MATERIALS:
CFRP: Tyfo® SCH-41H, Tyfo® CWEB-41, Tyfo® SCH-41-2X
Primer: Tyfo® S Epoxy & Thickened Tyfo® S Epoxy
Anchors: 1/4" Dia. Tyfo® SCH Composite Anchors
Cab-O-Sil (Epoxy thickening agent)
PICTURED: The structural health of the bridge before an rehabilitation work had started on the structure.
PICTURED: The structural health of the bridge before an rehabilitation work had started on the structure.
SURFACE
PREP:
The surfaces on the floor beams and arches of the bridge were fully prepared, providing a minimum of CSP-2 surface roughness. The surface preparation cleared all the laitance, dust, grime, etc. located on the surfaces to properly install the FRP material. The following photos demonstrate the cleaned surface ready for the application of carbon fiber material.
ABOVE: Outside Arch Surface Preparation.
ABOVE: Floor Beam Surface Preparation
ABOVE: Inside Arch Surface Preparation
SOLUTION:
After completing all required surface preparation, a prime coat of thickened Tyfo® S Epoxy was applied to the substrate to fill all minor imperfections, deflection, voids, etc., in the substrate prior to installation of the saturated fabric. The TYFO CFRP material fabric was hand saturated to ensure impregnation of all fabric with Tyfo® S Epoxy. All air bubbles were worked out of the system. System was leveled set and sealed using an additional coat of thickened Tyfo® S Epoxy.
The carbon fiber was then sand sprayed to match the texture of the rest of the bridge. After the CFRP and the Tyfo® S Epoxy were properly cured, a layer of acrylic painting was applied to every arch and floor beam installed with CFRP. The following photos show the completed CFRP application on the arches and floor beams along with the acrylic paint coating.
ABOVE: Finished Floor Beam CFRP Installation
ABOVE: Floor Beam CFRP Installation
ABOVE: Inside Arch CFRP InstallatioN
ABOVE: Finished Inside Arch CFRP Installation
ABOVE: Floor Beam Acrylic Coating
ABOVE: Arch Acrylic Coating
CONCLUSION:
After completing the CFRP installation, a thorough inspection of the work was done, recording the materials used, and a sample panel (Appendix 2), for future tensile testing (by others, if required) was cast in accordance with ASTM-D-/D3039, revision 12/2002. An adhesion test was performed on multiple locations by a qualified CSC employee following ASTM criteria. CSC walked the project with SPS New England, Inc. on-site Superintendent who was notified of pending demobilization and communicated no issues found. All CFRP areas were broom cleaned and CSC demobilized on 12/17/2021.
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