The 18-story David Whitney building, located in Downtown Detroit, Michigan, is a historic skyscraper. The building, constructed in 1915, is one of just three remaining Detroit buildings designed by renowned architects Daniel H. Burnham & Company.
Water Infiltration Delays Redevelopment
Currently owned by The Roxbury Group, the building underwent a full redevelopment to become a mixed-use site, including hotel space, luxury apartments, and restaurants.
While the redevelopment project was underway, active water leakage was occurring within the substructure, specifically at multiple and radiating hairline cracks, construction joints and honeycombed concrete locations. Seepage also existed at old beam pockets, around mechanical penetrations and abandoned ground anchors. The substructure houses a critical dry storage room for restaurants, hotel laundry, office space, fire suppression control panels, IT and phone systems. The spaces could not be finished until the water infiltration issues were addressed.
The owner had considerable past experience dealing with proposed solutions that included localized crack injection repair utilizing urethane based technology – a temporary fix that would not meet the prolonged needs of the building. A long-term repair solution was needed – one that would not involve continued yearly maintenance.
PULLMAN and STRUCTURAL TECHNOLOGIES, both Structural Group companies, were hired to investigate the water intrusion challenges, perform a root cause analysis, determine the best repair option(s), and implement a solution.
One of the many challenges was determining the structural makeup of the 100-year old concrete foundation structure, including the reinforcing patterns and wall thickness, since the building’s historical data was unavailable. Another challenge was to develop a cost effective solution when determining the scope and extent of grouting work because the owner did not have water control as part of the redevelopment budget.
Grouting Solution Developed and Implemented
Acrylamide chemical grout was selected by STRUCTURAL TECHNOLOGIES as the most cost effective and highest performance material for this type of application. PULLMAN created a 350 SF mock up area with substantial water infiltration to demonstrate performance and unit pricing. Mock-ups like this help quantify material usage, port-to-port spacing, proper grout set times for controlled migration lengths and crack penetration, and mix proportions/concentrations. Because wall thicknesses were unknown, the mock-ups also verified pump pressures, volumes, and drilling time.
Acrylamide grout is a two part system consisting of components “A” and “B”. These are blended separately and then subsequent components are pumped into place with a stainless steel, 1-to-1 pump. Before the acrylamide chemical grout was ready for injection, the right mixture had to be developed. Mixing ratios will vary depending on crack size, port-to-port spacing, desired set time, size and amount of voids to be filled and interior humidity conditions.
Component “A” is the acrylamide monomer, with an accelerator, a colorant, ethylene glycol (if freeze/thaw conditions are prevalent); component “B” is the oxidizer or hardener with added colorant and ethylene glycol (when required). Food coloring was used as an additive colorant for differentiation of chemical grout from ground water. The “A” and “B” components were injected in sleeve ports with ball-valves for control and monitoring. The team established an ideal cure time of 30 seconds.
PULLMAN crews pumped the grout beginning at the lowest point moving upwards. Pumping continued until the chemical grout was transmitted from port to port. Once transmission of the grout was visible, which was determined by the colorant intensity, shutoff valves were closed and the process continued throughout the grid pattern.
Solution Stops Water Infiltration Completely
In addition to the mock up area, PULLMAN crews performed an additional 1,000 SF of curtain wall grouting at strategic leakage locations throughout the remainder of the three-story substructure. Substructure grouting was completed successfully based on subsequent drying of the entire subsurface wall areas; thus allowing the owner to proceed with developing it into the spaces needed for on-time occupancy.
The team efforts of PULLMAN and STRUCTURAL TECHNOLOGIES went beyond improving the water infiltration issue – the team provided a turnkey solution to stop the issue completely.