Problem:

At a newly constructed Majestic Steel Distribution facility in Blytheville, Arkansas the geo-piers supporting several spread footings began to fail. These spread footings were designed to support an overhead crane inside the building, but the structure had been built on silty, mixed soils that proved unstable. Over time, the soils began washing out due to groundwater presence, causing the geo-piers and spread footings to lose support. As a result, the structural integrity of the overhead crane system was at risk, creating concern for both operational safety and the long-term performance of the facility.
Complicating the situation further, the soils beneath the floor slab required stabilization, but lifting the floor was not an option. Any upward movement could jeopardize other components of the new construction, making precise soil stabilization critical.

Solution: 

To stabilize the soils surrounding the spread footings without lifting the floor, Superior Grouting selected NCFI-4RH (formerly 24-003) polyurethane. The team drilled 1.5-inch injection holes to access the problem soils and strategically performed injections around each footing. This approach allowed the team to target the load-bearing soils directly supporting the crane footings, improving their ability to safely transfer structural loads.
The project involved six spread footings, with twelve injection points installed around each footing. Polyurethane was injected at depths of 4, 8, 12, and 16 feet using a top-down injection approach to ensure the soils were stabilized throughout the affected zones.

Results: 

The stabilization project was completed in approximately one week. The injections successfully densified and stabilized the surrounding soils without causing any lift to the floor slab, which was an important aspect of the injection program. Most importantly, the restored soil conditions provided reliable support for the spread footings, allowing the overhead crane system to operate as intended without concern for settlement or instability.
Throughout the process, construction activities were able to continue around the Superior Grouting team, minimizing disruption to the ongoing build. To maintain strict control during injection, the crew used laser levels to monitor slab movement and watched for surface “bumps,” which can occur when expanding polyurethane encounters the underside of the concrete. This careful monitoring ensured the soils were stabilized while protecting the integrity of the slab and surrounding construction. By restoring support beneath the footings without disrupting the slab, Superior Grouting was able to protect both the structural performance of the crane system and the overall construction timeline.