Cà d'Zan Estate - Winter Home of John & Mable Ringling Sarasota, Florida
Historical two-story residence constructed in the early 1900's on the grounds of the Ringling Museum of Art on Sarasota Bay. The structure consisted of reinforced concrete beams and columns over a cast in place foundation.
The foundation walls exhibited severe erosion of the cement paste at the inner concrete face due to long term wetting and drying from periodic flooding of the basement. The depth of carbonation was verified by petrographic analysis, which determined the average profile of vertical repair required.
The colonnade at the exterior perimeter between the first floor main hall and the waterfront terrace was encased within architectural terra-cotta cladding and abutting steel framed ornate windows and doors. Selective demolition of the concrete inside revealed spalling all around the circumference due to corroded vertical reinforcing steel.
Soft, powdery and hollow areas of the foundation were marked in the field and excavated back to achieve a sound profile to provide a hard fractured aggregate interface to receive the new concrete. The new face was tied together with epoxy set dowels at a uniform grid spacing having bent hooks to engage vertical sheets of welded wire fabric laid up in the center of the forms. The finished concrete placements provided durable cover prevent further migration of carbonation thereby extending the serviceable life of the foundation.
In order to repair the spalled columns at the arched terrace colonnade it was necessary to remove and reinstall the architectural steel door casements and terra-cotta cladding. Once exposed the arched beams were shored to relieve axial loads from the columns and allow temporary removal of the deteriorated concrete. The rusted wide flange steel shapes inside were sand-blasted clean and coated with an epoxy-modified cementitious bonding and anti-corrosion agent. Prior to placing new low permeability micro-concrete the vertical reinforcing was replaced with new bars and closed hoop horizontal ties to meet current code requirements for cross section and coverage.
The entire perimeter of the foundation as well as some intermediate stem walls were excavated back an average depth of 4 inches, formed and poured back up to height of 4-feet, which was a nominal limit above the documented tidal surge zone.
A total of (8) columns were fully chipped away, cleaned free of rust, reinforced, formed and poured back with (6) along the outer row and (2) at the inside corners of the transverse sides. All existing dimensions were maintained to allow reinstallation of the delicately restored arched door frames and terra-cotta cladding.
Owner: Ringling Museum of Art/Florida State University
Total Cost: $350,000