Aquajet Hydrodemolition Robot Used for Parking Garage Renovation

Published: 30/9, 2019

In Cincinnati, the deteriorating parking garage of a luxury condo complex has to be renovated.   

The project would require extensive removal of damaged concrete, work traditionally accomplished by handheld pneumatic tools. Renovations such as this have developed a negative reputation for bombarding surrounding neighborhoods with dust, noise, and extensive disruptions.  

Because the complex is an active building, the appointed contractor would be challenged with completing the renovation on time and budget while minimizing common construction disturbances, such as dust and noise. Additionally, the contractor would need to find innovative ways to manage potential interruptions to accommodate the active parking garage, as well as skillfully navigate complex phasing to allow residents to continue using the garage during construction. 

Structural Systems Repair Group (SSRG), the project’s general contractor, discovered a sizable amount of deferred maintenance that needed to be addressed, adding to an already ambitious renovation. SSRG estimated 480 yd3 (367m3) of repairs spanning 30,000 ft2 (2,787 m2) of surface area were needed, with certain levels of the structure requiring over 60% replacement. To complete the project on time, the contractor needed to implement a highly efficient technique — hydrodemolition. 

Before work could begin, SSRG had to plan project phasing to ensure the garage remained functional for the tenants throughout the renovation. This proved a challenge due to the garage’s unique design. The 5-story parking garage sat at the base of the high-rise apartment building and was engineered to account for the steep hill on which it was built. It rested at-grade on the north side and at walkout level on the other. 

Additionally, given the delamination of the concrete structure, the project required extensive shoring, resulting in installation of more than 800 shoring posts. The contractor worked from a global grid, gridding the entire floor instead of just localized beams to ensure the structure was supported appropriately. Workers also installed hard barriers composed of plywood walls and plastic to separate working zones from occupied space to ensure residents — and their vehicles — remained unaffected.  

The operator directed the Aqua Cutter 710, jetting water at 15,000 psi (1,034 bar), to remove the damaged concrete to varying depths. This ranged from 4 in (101 mm) to full depth, depending on the level of deterioration. In total, the robot removed about 480 cubic yards of concrete, jetting about 24,000 gallons (90,850 liters) of water per 10-hour shift.  

Workers built barricades to contain water and debris as the robot removed concrete. They routed the water across each level of the garage and through a series of filters, allowing gravity to help with debris removal. By the time the water reached the lowest level, most of the slurry had already been removed. SSRG then pooled the water to ensure it met the standards of the Metropolitan Sewer District of Greater Cincinnati. From there, SSRG pumped the water safely into the city’s sewer system. 

SSRG was able to greatly reduce the labor needed for the concrete removal work. The company’s traditional methods would have required upwards of 30 workers, but SSRG needed only a crew of six with the aid of the hydrodemolition machine. Two operators manned the robot while four workers handled water control, edge detail work and removal of material as the Aqua Cutter worked its way through the jobsite. The robot was fed high-pressure water by a Hammelmann power pack.  

The hydrodemolition robot handled the bulk of the concrete removal, but pneumatic breakers were still used for detail work. SSRG used a PAM OVE positioning device manufactured by RNP Industries for overhead demolition. The combination of the hydrodemolition robot and overhead chipping equipment spared workers from bearing the physical strains of long periods of handheld breaker operation.   

SSRG managed the complicated parking garage renovation with nearly 25 fewer workers than typical for a job of this magnitude. At the same time, the contractor virtually eliminated disturbance to the building’s residents, while staying on track to its deadline. These efficiencies added up to significant cost savings for the contractor and the owner. SSRG saved over 10,000 staff hours on the job versus conventional methods.