Ohio Polyurethane Grouting
The Job
This Ohio polyurethane grouting project by CJGeo was for a short line railroad near Scio, Ohio. The railroad received numerous complaints from motorists about a settled grade crossing. The settlement of the precast grade crossing was great enough to also require a speed restriction for rail traffic.
The Challenge
When this precast grade crossing settled, the clips holding the rail to the crossing panels broke. This allowed significant differential settlement between the various panels. The differential settlement was up to two inches.
In order to install new clips, the panels generally have to be within 3/8-inches of the adjacent panels’ elevation. If any debris has accumulated between the rail foot and bearing surface of the precast panels, which in this case were Oldcastle’s StarTrack.
The Solution
Having repaired multiple precast crossings for this short line, they reached out to CJGeo about performing this Ohio polyurethane grouting project. CJGeo proposed CJGrout 40NHL geotechnical polyurethane grout to the railroad. CJGrout 40NHL is formulated for high dynamic loading environments, and is excellent for different settlement correction of thick pavements.
CJGeo mobilized a polyurethane grouting crew to the site. Due to relatively low traffic on the line, the customer was able to provide an eight hour window for the repair, and the DOT allowed a complete road closure, as the settlement affected both lanes, with the centerline being the worst spot on the crossing.
CJGeo crews used mechanical assistance to address some of the worst differential settlement. Cleaning the accumulated debris between the rail foot and panels was key to facilitating complete correction of the differential settlement. After CJGeo wrapped up the polyurethane grouting, the railroad’s maintenance-of-way crew installed new clips, replaced the boots, and patch the adjacent asphalt.
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Michigan Polyurethane Grouting
The Job
This Michigan polyurethane grouting project is located near Saginaw, Michigan. The work was done to stabilize the settling basement floor of a sugar beet processing facility.
The Challenge
This facility is nearly 100 years old, and has been settling for as long as anyone currently working there can remember. Over time, as the facility has been expanded, various things have been done to address the settlement. All of the repairs have been to accommodate the settlement, such as adding beams below floors, mass reinforced concrete of footings, etc, but nothing done with the problematic soils below the facility.
Due to nature of sugar manufacturing, process liquids with high sugar content discharging onto the floor is relatively common. Some of this sugary water inevitably flows through joints in the floor, saturating the subgrade with sugary water.
Sugar kills the curing of cement-based grouts, so traditionally cementitious grouting was not an option here. Cementitious grouting is also incredibly difficult to perform as food-grade clean process.
The facility and their consulting structural and geotechnical engineers reached out to CJGeo to see if polyurethane grouting was a good option to address the approximately 10′ of soils below the floor with inadequate bearing capacity.
The Solution
CJGeo’s operations and engineering team evaluated the geotechnical and structural information and determined that a polyurethane and chemical grouting program would be appropriate.
The plan to address the underlying soils and water exfiltration from the basement involved two primary grouting programs. First, compaction grouting using a potable water certified plural component geotechnical polyurethane grout, CJGrout 35NHV61.
The next step of this Michigan polyurethane grouting project was to underseal the floor with single component chemical grout. The goal here was to effectively coat the bottom side of the slab to reduce the ability of process water to exfiltrate the basement and resaturate the underlying soils.
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Bridge Approach Grouting
The Job
This bridge approach grouting project is located near Lexington, Virginia. It is on Interstate 81, which has some of the highest truck traffic in Virginia. The Virginia Department of Transportation maintains this section of Interstate 81.
The Challenge
Settlement over time caused voids under three lanes of approach slab at an overpass structure. During precipitation events, the voids became saturated, and then act as diaphragm pumps. The high dynamic loads from the heavy truck traffic effectively pump the fines out of the saturated base materail.
Over time, this resulted in extensive deterioration of the adjacent asphalt pavement, along with distress of the concrete approach slabs.
The Solution
Working with the local bridge maintenance group and their on-call maintenance contractor, CJGeo proposed a polyurethane bridge approach grouting program to restore stability to the slabs. Previous repair attempts had used flowable fill to attempt to fill the voids below the pavement. This generally doesn’t work very well, and proved to not be suitable in this case, either.
Primarily constrained by maintenance of traffic concerns, CJGeo undersealed all three lanes of the approach over two nights. Grouting was done using CJGrout 40NHL, which is optimized for heavy loads, wet environments, and is capable of lifting settled pavements.
Because 40NHL cures to 95% within a few minutes, by the time the injection holes are patched, treated slabs and soils are ready for traffic as usual.
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Virginia Polyurethane Grouting
The Job
This Virginia polyurethane grouting project is located in Blacksburg, Virginia, at Virginia Tech. The work was done to support continued occupancy of the structure, after voids as deep as two feet were located below the floor slab.
The Challenge
A small area of the ground floor slab on grade settled, primarily adjacent to the basement, which is only under about 20% of the building footprint. The basement contains mechanical equipment, and ties to a large crawlspace used as a ventilation duct.
Upon initial discovery, the university’s on-call geotechnical and building envelope consultant performed exploratory drilling to determine the extent of voids. Several auger bores for exploration of the backfill material identified poor control during installation as the most probable cause of settlement.
The Solution
CJGeo was the most responsive bidder on the owner’s solicitation, which called for filling the voids below the floor with CJGrout 20SDB geotechnical polyurethane. 20SDB is specifically formulated for maximum expansion, high mobility, and very low exotherm.
One particular challenge was the amount of glass gravity drain piping below the floor. Because much of the building is lab space, when it was built, the most chemical-tolerant pipe available was glass. So, it was very important that the polyurethane grouting work not damage the relatively fragile pipes.
CJGeo timed its work around spring break to avoid any disruption to classes, research, and offices. The work took six days onsite, and a total of just under 10,000 pounds of CJGrout 20SDB.
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Apartment Floor Lifting
The Job
This apartment floor lifting project is on a military facility in Washington, DC. During turnover of a unit, the property management company discovered signs of significant settlement affecting the interior floor. There was a significant crack showing through vinyl flooring, and up to 1.5 inch gaps below the baseboard in a carpeted room.
The Challenge
The primary challenge for the general contractor on this project was repairing the floor as quickly as possible. The unit was only going to be unoccupied for about two weeks between tenants. The contractor not only had to repaint, install all new floors, but also had to address this settlement.
The Solution
The general contractor reached out to CJGeo to assess the feasibility of raising the floor using polyurethane grouting. Having worked together in the past, the general contractor knew that CJGeo’s polyurethane grouting process is significantly faster than traditional mud jacking or concrete replacement.
A single CJGeo polyurethane grouting crew took less than a day to complete this apartment floor lifting repair. The total area grouted was around 750 square feet. Using CJGrout 28FDL, the grouting process corrected all of the settlement. Because polyurethane grouts are about 95% lighter than traditional grout and backfill materials, the likelihood of the grout material inducing future settlement is virtually eliminated.
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Maryland Concrete Lifting
The Job
This Maryland concrete lifting project is located in Frederick, Maryland. The project is for the MARC system, on tracks also used by CSX.
The Challenge
MARC’s Brunswick Line includes a spur to Frederick, which utilizes a freight track that also serves multiple industrial sites, including quarries and concrete plants. As it winds through an industrial area towards the Frederick station, the line crosses multiple arterial roadways. As Frederick grows, traffic is increasing significantly with both cars and industrial truck traffic.
At two crossings, bellies have developed in the precast modular grade crossings. Water collects at the low spots, which then reduces bearing capacity of the base, causing deterioration of the adjacent asphalt pavement. This deterioration causes spalling of the panels, and ride quality problems for motorists.
The Solution
CJGeo’s rail grouting experience includes dozens of precast modular grade crossing stabilization projects. Working with the rail system’s on-call MOW contractor, a CJGeo polyurethane grouting crew grouted each of the two crossings in a day, each.
CJGeo uses CJGrout 48NHL, which is specifically formulated for high dynamic load applications. 48NHL provides multiple factors of safety from a compressive strength perspective, but is slightly elastomeric, which makes it much more durable than mudjacking or traditional cementitious pressure grouting grouts sometimes used to stabilize modular grade crossings on a temporary basis.
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New Jersey polyurethane grouting
The Job
This New Jersey polyurethane grouting project is located in Creskill, New Jersey. As part of a full gut renovation of the library, the architect specified lifting settled areas of the floor. The floor settlement was affecting approximately 3200 square feet, with settlement up to two inches.
The Challenge
The library building is a slab on grade, with relatively light design loads. The floor is approximately four inches thick, and reinforced with welded wire mesh. The original design to correct settlement was to use mud jacking. Mud jacking works well, but is rather slow, and tends to be very messy. Mud jacking uses cement-based grout pumped under high pressure below concrete to fill voids and push the concrete back up. A downside is that the grout is quite heavy, and the additional weight it adds to already compromised soils can cause additional future settlement.
The Solution
CJGeo proposed using CJGrout 28FDL geotechnical polyurethane grout as an alternative to the specified mud jacking process. CJGeo’s value engineer proposal was based on the following benefits of polyurethane grouting over traditional cementitious grouting:
- speed – polyurethane grouting tends to be significantly faster than cementitious grouting
- cleanliness – polyurethane grouting is a very clean process, including dustless drilling, mechanical connections to the slab, and material that scrapes off with a putty knife if it leaks from below a slab
- density – traditional mud jacking grout is approximately 50 times heavier than in place CJGrout 28FDL. This reduces the likelihood of future resettlement by minimizing the additional load that grout places on the underlying soils.
The architect and structural engineer accepted CJGeo’s value engineering proposal for this New Jersey polyurethane grouting repair. A crew of three CJGeo polyurethane grouting experts completed the repair in less than a day. Because polyurethane cures within a few minutes, the general contractor was able to move on to the next steps in the project very quickly.
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Bridge Approach Ground Improvement
The Job
This bridge approach ground improvement project by CJGeo is located in Richmond, Virginia. With multiple S curves and merges, I-195 in Richmond, Virginia is one of the most accident prone sections of interstate in Central Virginia. Significant settlement of multiple approach and departure slabs at various bridges didn’t make things any better. Improving the ride quality by addressing up to 6 inches of settlement was a critical part of a 2022 safety improvement plan.
The Challenge
Extensive settlement over the years had caused the pavement to become distressed. This was addressed over time with extensive patching of the pavement slabs. With no reasonable detour routes, shutting down traffic to facilitate repairs was not an option.
The Solution
While the original project designed required lifting all of the settled pavement, this would have been nearly impossible, given the extensive patching (including full depth filling of expansion joints with repair mortar).
CJGeo worked with the general contractor and VDOT to revise the repair plan to a combination of compaction grouting of the underlying soils, coupled with an asphalt overlay of the approach and departure slabs to restore the ride.
Polyurethane compaction grouting was performed to a depth of up to 25′ below the pavement surface. This was to consolidate poorly controlled backfill material, at two approaches (9 lanes total) and three departures (9 lanes total). Cutoff criteria was 0.05 inches of lift at each point/stage.
Milling and paving for a 30′ taper to provides a smooth transition and ride.
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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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