Office Floor Settlement Repair
The Job
This office floor settlement repair project is located near Norfolk, Virginia. The slab floor inside of a grain import/export facility office sank both differentially and globally. All exterior walls are on driven timber piles, but the floor floats independently of the foundations. Slab settlement up to 3 inches affected approximately half of the building footprint.
The Challenge
Over the roughly 15 years that the floor was settling, maintenance crews were constantly repairing various systems. These repairs were including tuckpointing CMU walls, moving/shimming HVAC ducting, and rerouting water lines.
The foundation repair work on this building couldn’t impact operations. Ship loading and unloading could not be disrupted for any reason. The settled building houses many operations critical to ensuring timely loading and unloading.
The Solution
CJGeo proposed polyurethane grouting for this slab foundation repair project. Polyurethane grouting is safe, fast, and economical for floor settlement repair. Structural polymer grouting is another name for polyurethane grouting. The material of choice was CJGrout 28FDL. 28FDL is optimal for lifting light duty commercial floors experiencing both global and differential settlement.
CJGeo mobilized two polyurethane grouting crews to the facility on a Saturday morning. The 4,000 square foot repair only took nine hours start to finish. There were zero disruption to operations. During lifting, previous cosmetic repairs were undone to facilitate lifting. This included removing extensive patch material from the CMU walls, loosening plumbing connections, and adjusting HVAC ductwork.
By mobilizing multiple crews with multiple equipment redundancies, CJGeo was able to ensure that the repair had zero disruptions to the facility and its operations.
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Port Shed Floor Stabilization
THE JOB
This port shed floor stabilization project is located in Baltimore, Maryland. The 11″ thick slab floor of a storage shed at a port facility settled up to 6 inches. Exploratory coring & non-destructive imaging (GPR & microgravity) indicated there were extensive voids below the floor.
Previous work on the adjacent bulkhead uncovered extensive voids below the exterior footings (pile-supported) and multiple abandoned, but unfilled, pipes under the floor.
THE CHALLENGE
Due to relatively thin voids, which were all less than 6 inches, and void filling grout had to be highly mobile. However, this posed environmental challenges due should the grout make its way into an unfilled abandoned pipe and into the adjacent waterway. The owner did not want to lift the floor, so grouting had to be sufficiently low mobility to prevent runaways, but also fill all voids at an economical hole spacing.
THE SOLUTION
CJGeo proposed polyurethane grouting for this slab foundation repair project. The original design was for a 50/50 mix of polyurethane and cement grouting. CJGeo proposed a valued engineering proposal to perform all grouting with polyurethane. CJGrout 35NHV geotechnical polyurethane grout was proposed to balance mobility for completeness of fill and reaction time to avoid any runaway loss into the adjacent waterway.
CJGeo mobilized a two-reactor polyurethane grouting rig and installed approximately 6300lbs of polyurethane grout over a three-day period. Pneumatic rock drills were used to speed drilling.
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Commercial Floor Void Fill
THE JOB
This commercial floor void fill project is located in Manhattan. During a Local Law 11 inspection, the owner of a coop building’s first floor asked the GC to investigate a settled slab floor inside part of the building. The contractor began opening up a 2′ square hole in the floor. During this, all the debris was disappearing. After opening the hole it was apparent why. There was a 2′ to 3′ deep void around the entire perimeter of the building footprint.
THE CHALLENGE
Filling a 90CY void under the floor of an operating business can be a challenge anywhere. Complicate it with a 40′ x 10′ laydown area, Mid-Town Manhattan traffic, and cold winter temperatures, and you’ve got quite the challenge.
The cause of settlement was the consolidation of poorly placed fill, which was primarily construction debris. Lightweight void filling material is best to minimize future settlement of the underlying fill material.
THE SOLUTION
At the suggestion of an on-staff structural engineer, the general contractor’s project manager reached out to CJGeo about performing polyurethane grouting to fill the voids. CJGeo proposed using a low-exotherm, high mobility bulk void filling foam to fill the voids. 3′ deep voids are too deep to fill with most polyurethane grouts. A true low exotherm foam is needed for efficiently and safely filling any voids thicker than about 6″. High mobility foams are also critical when filling voids in order to ensure complete coverage.
CJGeo mobilized a two-reactor polyurethane grouting rig. The CJGeo crew installed approximately 4800lbs of CJGrout 20SDB geotechnical polyurethane grout over a two-day period. CJGeo pulled continuous negative pressure on the void through the floor. This was to allow for continuous operation of the facility during grouting. CJGeo’s work didn’t disturb operations at all. All of the voids were completely full of grout at the end of the project. The polyurethane grouting process used here for slab foundation repair is sometimes also called slab jacking or structural polymer grouting.
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Bridge Approach Polymer Grouting
The Job
This bridge approach polymer grouting project is located just outside of Washington, DC. The George Washington Memorial Parkway connects Washington, DC with Fairfax and Alexandria Counties in Virginia. Originally designed as a scenic route, the road has transformed into a heavily used commuter route in and out of Washington. The road runs along the Potomac River, with bridges crossing deep ravines, including Windy Run.
The Challenge
Our biggest challenge with this project was making sure this heavily populated commuter route was completed in a timely fashion.
The Solution
CJGeo proposed polyurethane compaction grouting using CJGrout 30NHL. CJGrout 30NHL’s design is for improving the bearing capacity of loose soils similarly to cementitious compaction grouting. Grouting is done on 4’ centers, at 5’, 10’ & 15’ below grade. Top-down grouting ensured maximum densification of underlying soils. This grouting program was generally prescriptive, but with ground movement of 0.5 inches cutoff criteria.
CJGeo installed approximately 25,000 pounds of CJGrout 30NHL to increase the bearing capacity of the embankment soils. Due to polyurethane grout’s nearly immediate cure, CJGeo helped ensure that ground improvement stayed out of the critical path of this accelerated project. Pre & post grouting DCP testing showed improvement in soil density.
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Chemical Underpinning
The Job
This chemical underpinning project is located outside of Pittsburgh, Pennsylvania at a manufacturing facility. Water began to seep through the floor of the shop, break room, and bathrooms inside a manufacturing facility. The investigation determined that a water line had broken, and weekend soils below the floor, causing the settlement. Voids were also present below the floor.
The Challenge
The client’s primary concern was addressing the stability of the area without affecting normal usage.
The Solution
CJGeo proposed chemical grouting to stabilize the weakened soils, along with structural polyurethane grouting to fill voids. Previous repairs to address floor settlement had been completed, so a hydro-insensitive undersealing polyurethane grout was used to ensure stability without lifting the slab.
Due to saturated soils, CJGrout 35NHV was the best material for filling voids immediately below the floor. 35NHV is a normal speed, hydro-insensitive geotechnical polyurethane, specifically formulated for void filling applications. It provides high bearing capacity, and minimizes the chance of undesirable lifting during installation.
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RCP Pipe Sealing
THE JOB
This RCP pipe sealing project is located in Wake Forest, North Carolina. The asphalt parking lot over a 300′ run of 54″ RCP culvert kept collapsing. The locality’s public works department determined that the installation crew had not properly gasketed or seated the joints between the 4′ sticks of pipe. The pipe saw the continuous flow of a small stream. Flow enters at an end wall and discharges into a box culvert that crosses a public street. The drop inlet at the downstream junction between the RCP culvert and box culvert also had a failed 18″ RCP culvert feeding it. This had been repaired multiple times using open trench excavation.
THE CHALLENGE
The municipality was looking for an affordable, proven, and non-disruptive solution. Replacement would have required removal of a structure, and prevented adjacent businesses from using their parking lot during the work. Relining was not practical due to multiple sewers and water utility lines crossing through the pipe. Significant joint offsets would have also made lining difficult.
Extensive voids were identified around the pipe through an inspection. Much of the water flow from the stream was passing under/outside of the pipe, causing the erosion and collapse of the overhead parking lot, and the floor of a storage building built over the pipe. Previous attempts at sealing the joints and filling voids around the pipe with concrete had failed.
THE SOLUTION
Polyurethane grouting fill voids around the pipe and seal the joints between the individual pieces of pipe, end wall and drop inlet. And, chemical grouting to treat a curtain at the upstream end to reduce subsurface flow, and at the downhill end to stabilize a joint in the failed small diameter RCP culvert entering the drop inlet.
CJGeo polyurethane grouting crews placed 50 cubic yards of CJGrout 35NHV61, hydro insensitive polyurethane and 45 gallons of polyurethane resin chemical grout for an upstream grout curtain over a period of three days to complete the repair. The repairs were all completed without disruption to the adjacent businesses or streets.
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Facing a similar challenge to this RCP pipe sealing 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.
15 inch RCP point repair
The Job
This 15 inch RCP point repair project is located near Richmond, Virginia. A 6′ deep sinkhole opened up adjacent to a stormwater manhole structure. The manhole was in an easement between two single-family homes and maintained by a municipality. Two misaligned joints were visible from the manhole and were the cause of the sinkhole.
The Challenge
The two misaligned joints were under up to 8′ of cover. The repair had to seal the two misaligned joints and fill the extensive voids around the pipe that resulted from years of erosion.
Due to extensive utilities in the area, and difficult access, the owner did not want to perform an open cut repair. While the misalignment was significant, the reduced flow from the misalignment was less problematic than an open cut repair.
The pipe is located approximately 150 feet from the nearest roadway, on a steep slope towards a resource protection area. All of these factors significantly increased the costs & disruption of an open cut repair.
The Solution
CJGeo proposed grouting via driven tubing to seal the joints in the pipe. An internal form was used to minimize the entry of chemical grout into the pipe.
CJGeo’s large diameter pipe repair crew installed CJGrout 35NHV geotechnical polyurethane to seal the two misaligned joints and fill voids. The repair took less than two hours, with no service disruptions. CJGrout 35NHV excels at repairing failed RCP joints because its reaction profile is designed for void filling, and it’s unaffected by water. The homeowners and owner were happy that the repair only took foot traffic and a lightweight 2″ hose bundle.
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25VF stormwater manhole sealing
THE JOB
Leaks throughout the joints on a 25VF, 48″ precast stormwater manhole were leaking. This caused a large sinkhole to open up at the surface, adjacent to the structure, requiring manhole sealing. Homeowners on either side of the easement were concerned about the stability of the area and reached out to the municipality. The estimated cost for excavating the structure to repair it from the outside exceeded $50,000.
THE CHALLENGE
Due to the depth of the manhole, a confined space entry had to be used. Additionally, the grout had to tolerate high moisture levels in the adjacent soil, and economically fill the extensive voids. Due to the presumed large size of voids, the grout had to also be low exotherm.
High-density geotechnical polyurethane grouting fills the sinkholes adjacent to the structure and seals all points of infiltration.
THE SOLUTION
CJGeo polyurethane grouting crew sealed all of the infiltration points and filled the sinkholes in a single day. No excavation was required. The cost of the manhole sealing was less than 20% of that of open excavation.
The CJGeo crew used CJGrout 35NHV, which is specifically formulated for use around buried structures. It has a moderate reaction speed to helps reduce the number of injection holes. It’s hydroinsensitive, meaning even when injected directly into standing water, it reacts the same as in a dry environment. Hyrdoinsensitivity is important for water intrusion repair applications.
After drilling 5/8″ holes through the structure’s walls, 35NHV is injected through mechanical packers. There were two cutoff criteria for this project:
- 35NHV geotechnical polyurethane extruding through the full circumference of each joint in the precast structure
- grout coming to the surface from the bottom of the sinkholes
CJGrout 35NHV sets within two minutes, and reaches 95% cure within 15 minutes.
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Facing a similar challenge to this 25VF stormwater manhole sealing project? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
Runway Slabjacking
THE JOB
This runway slabjacking project is located in Norfolk, Virginia, at a military base. The hinge slab of a runway at an overpass settled. This caused up to a 1.5″ difference in elevation across the joint between slabs. The slabs had previously been repaired with pressure grouting. The previous runway slab jacking was done using a cement-based grout. The previous slab jacking required drilling 3″ holes on 4′ centers over the entire area. They had to be core drilled due to the 26″ deep slab.
THE CHALLENGE
The proposed repair had to work despite previous repair attempts with cement grout. The repair had to be completed in fewer than 48 hours, with the ability for air traffic at any time during the repair with as few as 10 minutes’ notice. The settled slab was nearly twice as thick as the adjacent slab, which was 14″ thick.
THE SOLUTION
CJGeo proposed polyurethane grouting to raise the settled slabs. Polyurethane grouting allows for immediate resumption of traffic and is much more efficient to install than cement-based grout.
Because the previous repair had left hundreds of 3″ core holes through the slab, polyurethane grouting was idea due to its 5/8″ hole diameter. CJGeo proposed a 6-pound foam (CJGrout 60NHL) for this project, which was originally specified for cement-based grout. 6-pound foam provides adequate bearing capacity and has excellent lifting capacity.
Polyurethane grouting can also be performed in the rain without affecting the material. Due to the extremely short runway shutdown period, the speed of execution despite any bad weather was critical.
CJGeo mobilized three polyurethane grouting rigs to the site for this runway slabjacking project. The joint was saw cut full depth using a 48″ walk-behind saw prior to lifting. Lifting was done using up to four polyurethane reactors running simultaneously. Drilling was completed using a combination of pneumatic rock drills & electric hammer drills.
The runway settlement correction project was completed in less than the allotted time. CJGeo’s subcontracted to TST for this project. The project also includes restriping and asphalt pavement restoration on the runway shoulders.
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9″ Floor Lift
THE JOB
9″ floor lift for 6,000 square feet of slab floor in a flex space building in Boston, Massachusetts. The tenant of a warehouse space vacated at renewal due to challenges that the settlement caused for their operations. The tenant of the adjacent office portion threatened to not renew if the warehouse floor wasn’t lifted.
THE CHALLENGE
The building owner wanted to lift the warehouse floor to improve the function of the space. To avoid further upsetting the office tenant, repairs had to be quiet, dust free, not require moving any of their furnishings, and ensure long term stability.
The office space settlement correction repairs could only happen at night, so relying on material deliveries would be difficult.
THE 9″ FLOOR LIFT SOLUTION
CJGeo proposed plural component polyurethane grouting to the owner for this 9″ floor lift. Plural component polyurethane grouting is exceptionally clean, isn’t dependent on third party grout deliveries, and allows immediately return to service.
A five person CJGeo polyurethane grouting crew corrected all of the settlement in a single shift using CJGrout 28FDL. The vacant warehouse portion of the building was lifted during the day. Once the adjacent office closed for the day, the CJGeo crew completed the office space slab foundation repair overnight.
CJGrout 28FDL injection uses 5/8″ holes drilled through the slab. Because the holes are so small, dustless drilling is very easy. During installation, CJGrout 28FDL expands up to 24 times its liquid volume. Therefore, this entire project was done with material delivered to the site in CJGeo’s equipment. Cement grouting would have required multiple material deliveries, which would have made this 9″ floor lift project take much longer.
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