Dollar Store Floor Void Filling
The Job
This floor void filling project is located about three hours west of Richmond, Virginia. A commercial contractor was performing a full gut renovation of a dollar store in a strip center. The building was approximately 30 years ago, and there were no signs of floor slab failure or settlement.
The Challenge
While cutting through the floor to install utilities, a 3″ void was discovered below the floor. Exploratory coring determined that voids ranged from 0.5 to 4″ throughout approximately 11,000 square feet of the space. The front of the building is at grade, but the rear of the building has an approximately 7′ tall CMU stem wall, which was backfilled with common borrow during original construction.
The Solution
The general contractor reached out to the structural engineer to notify them of the problem. The structural engineer then reached out to the geotechnical engineering, who recommended polyurethane grouting as the best way to fill voids below a floor. The geotechnical engineering is familiar with polyurethane grouting from working with CJGeo on similar repairs in the past. They know that polyurethane grouting:
- is very clean and fast, so is unlikely to slow progress
- is very lightweight, so is least likely of all grouts to cause additional settlement
- effectively cures instantly, allowing immediate resumption of activities in the area
CJGeo mobilized two geotechnical polyurethane grouting crews to the site and filled the voids over a period of two days. It took about 7,000 pounds of CJGrout 20SDB through approximately 500, 5/8″ holes to completely fill the voids. Cut-off criteria was cross-hole communication. The work was performed without disruption to the renovation activities.
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Fire Station Floor Lifting
The Job
This fire station floor lifting project is located about an hour east of Richmond, Virginia. The concrete slab on the grade floor inside of a fire station on the North Neck of Virginia settled up to two inches. As part of the investigation into the cause, an engineer discovered voids up to 8″ below the slab and multiple broken sanitary sewer pipes below the floor.
The affected areas needing slab foundation repair included a dayroom, kitchen & meeting hall.
The Challenge
In order to minimize disruption to the fire station’s operations, the proposed repair had to be quick, clean, and minimize uncertainty associated with the plumbing repair slab cuts.
The Solution
CJGeo performed ground improvement grouting of the underlying soils to 5′ below-grade utilizing plural component polyurethane compaction grouting, with CJGrout 35NHV. During the compaction grouting process (sometimes called structural polymer grouting), the CJGrout 35NHV lifted the floor back into place.
Because polyurethane grouts cure very quickly, the floor was repaired the day before the plumbing work was scheduled. This allowed the plumbers a stable work surface and eliminated the risk of stuck saws or sudden collapse of the floor during floor sawing for plumbing access.
Grouting sufficiency was verified by using pre & post-grouting DCP tests.
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Facing a similar challenge to this fire station floor lifting project by CJGeo? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
Corporate HQ Stabilization
The Job
Starting immediately after construction was completed, the slab on the grade floor within the cafeteria, loading dock, and kitchen at a corporate headquarters building in Pittsburgh, Pennsylvania settled. Over the course of 12 years, the owner had four different grouting companies attempt to address the problem. Lime slurry injection below the slab was disruptive, and settlement always resumed shortly thereafter.
Compaction grouting was performed in one area but was so disruptive that despite the fact that it was the only method where settlement didn’t resume, the owner kicked the contractor off the site after nearly four months of not having access to their executive dining room.
The Challenge
Settlement progressed over time to be as much as four inches, affecting nearly 20,000 square feet of floor. A general contractor retained by the owner reached out to CJGeo about performing low-impact grouting to address the settlement.
Because settlement affected the entire kitchen, food prep, serving and majority of the dining areas, repairs had to be facilitated continued use of the facility. Additionally, due to the 24-hour staffing of the facility, the noise had to be limited, and there was zero tolerance for dust.
Video inspection of the extensive gravity sanitary and floor drains below the floor revealed six defects, including a 2″ offset in a sanitary drain line for a 6 stall restroom.
The Solution
CJGeo performed 17 DCP tests to determine the depth of uncontrolled fill, which was the presumed cause of settlement. DCP testing showed pockets of WOH fill down to 35′ below the finish floor, and voids ranging from 2″ to 18″ immediately below the floor.
Over the course of 7 nights onsite, CJGeo crews installed 12,000 pounds of CJGrout 20SDB into voids immediately below the floor, and 53,000 pounds of CJGrout 35NHV61 for polyurethane compaction grouting. Compaction grouting was performed up to 35′ deep, but to an average depth of 15′ over the entire area.
All work was completed off-hours. As soon as the kitchen shut down for the evening, CJGeo crews swung into action, grouting through the night until wrapping up in time for the food prep crews to get ready for breakfast at 0500.
To facilitate grouting under four walk-in freezers and refrigerators, over the course of a 24-hour shift, all cold contents were moved to reefer trailers, CJGeo grouted to 30′ under the freezers and refrigerators, which were then immediately turned back on, and then refilled.
Through careful coordination with multiple operational divisions for the owner, general contractor, flooring restoration contractors, plumbers, and remediation contractors, CJGeo successfully completed the project under budget and on time.
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Facing a similar challenge to this project? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
Sewer Collapse Sinkhole Repair
The Job
This sewer collapse sinkhole repair project is located in central Virginia. When the operators of a tire and auto shop noticed a sinkhole developing next to their building. They weren’t sure what to do. After an employee crawled into the hole and discovered that he could stand up underneath their building, the owner reached out to the city. City crews determined that a 20″ VCP combined sewer & storm pipe had collapsed under the structure, roughly 25′ below grade.
The Challenge
An on-call contractor for the city installed a new manhole and rerouted the pipe around the building. However, addressing the sinkhole was out of their businesses’ scope. The project manager reached out to CJGeo, who visited the site and recommended DCP testing to better quantify the extent of the problem.
The Solution
DCP testing showed that outside of the large hole on the surface, there was little deep disturbance. Working with the city’s consulting engineer, CJGeo developed a grouting plan to install two different CJGrouts. 20SDB in the bulk voids near the surface. And 35NHV61 for soil grouting to address voids within the underlying ground near the failed sewer line.
While onsite for just 6 hours, a CJGeo crew completed the work with zero disruption to the businesses’ operations.
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Facing a similar challenge to this sewer collapse sinkhole repair project? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
