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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Virginia Lightweight Fill
The Job
This Virginia lightweight fill installation is located Norfolk, Virginia. The placement is part of a low income housing development in an area subject to flooding. The site is located a few blocks from downtown Norfolk.
The Challenge
Like many coastal cities, much of the ground in Norfolk is infill. On this site, fill material was entirely uncontrolled. It included construction debris, organics, and silty sands. In order to bring the finish floor elevations above flood elevation, the site needed to come up by nearly eight feet in some areas.
The Solution
CJGeo worked with the structural engineer to design a lightweight backfill program that would help reduce anticipated settlements. After stone columns were installed across the site, the CMU building walls were built on poured footings. After the walls were in place, CJGeo filled the entire building pads with Ultra Lightweight CJFill, with an average density of 25lb/cuft.
CJGeo batched CJFill-Ultra Lightweight with a 80psi at 28 day minimum compressive strength using the dry batch process onsite, and placed at times more than 1,000 cubic yards per day.
Once the CJFill-Ultra Lightweight was in place, plumbers trenched in plumbing, and placed twelve inches of sand on top of the CJFill-Ultra Lightweight. The work took around two weeks, using the dry batch generation method.
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Stormwater Sinkhole Repair
The Job
This stormwater sinkhole repair project is located at a data center near Dulles, Virginia. Within a few months of construction, a depression started over a utility intersection within a street intersection inside the fence. Time showed that asphalt patching wasn’t going to solve the problem, so a geotechnical engineering firm was brought into investigate the sinkhole.
The Challenge
The first step taken was video inspection of all the gravity utilities in the area. None of them were showing any signs of leaks of water or soil. Utilities within the zone of influence of the sinkhole include:
- stormwater (deepest & largest)
- fire protection
- two fiber duct banks
- three electrical duct banks
Given the shear number and crossing alignments of utilities, and lack of leaks, the presumption was that backfill consolidation over the underlying stormwater structure was the most likely cause of the settlement.
The Solution
Due to the presumed cause of inadequate compaction, the geotechnical engineer recommended polyurethane compaction grouting to the owner. Compaction grouting with polyurethane grout is significantly faster, less disruptive, and less likely to displace adjacent structures than cementitious compaction grouting.
CJGeo proposed using CJGrout 20SDB for this stormwater sinkhole repair project. 20SDB is well suited for filling bulk voids, and has very little expansive pressure, so minimizes the chances of fouling or damaging the adjacent critical utilities.
A CJGeo polyurethane grouting crew was able to complete the repairs over two days onsite.
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Maryland compaction grouting
The Job
This Maryland compaction grouting project is located on East West Highway, in Chevy Chase. A few years after finishing construction of a new mixed use building with underground parking, the public sidewalks began to settle.
The Challenge
A local consulting geotechnical engineer was the first call by the building owner. After reviewing the construction drawings, and visiting the site, the geotech recommended performing a few hand augers. The hand augers were to:
- confirm the sidewalk construction matched the plans
- check for bulk voids below the sidewalk
- confirm the backfill material
- see just how loose the backfill material was.
The hand augers confirmed that the sidewalk was indeed pavers over asphalt, over a thin concrete mud slab. There were sporadic voids below the mud slab, up to six inches deep. The backfill material was poorly controlled soil, and was relatively loose.
The Solution
Due to the backfill material being relatively loose, and the building being new enough that the soils hadn’t consolidated on their own, the geotechnical engineer recommended polyurethane compaction grouting to the owner. Compaction grouting with polyurethane grout is significantly faster, less disruptive, and less likely to displace adjacent structures than cementitious compaction grouting.
CJGeo proposed using CJGrout 20SDB for this Maryland compaction grouting project. 20SDB is well suited for filling bulk voids, and has very little expansive pressure, so minimizes the chances of fouling or damaging drainage board.
A CJGeo polyurethane grouting crew was able to complete the repairs over two days onsite.
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Facing a similar challenge to this Maryland compaction grouting 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.
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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New Jersey Lightweight Fill
The Job
This New Jersey lightweight fill project is located in Secaucus, New Jersey. It’s part of a two building, wood framed multifamily structure over a concrete podium. The site is located very close to the Hudson River, so the underlying soils are poor, and there is a high likelihood of future flooding. As a result, the ground was improved using rammed aggregate piers, but then needed to be brought up approximately 2′ above existing grade.
The Challenge
Rammed aggregate piers were only able to improve the site soils so much. To avoid the costs of rigid inclusions or piles, the design team had to reduce the load applied by the backfill needed to elevate the site. The maximum unit weight was 30lb/cuft, and because of potential flooding, the material had to be permeable, in order to reduce uplift potential.
The Solution
CJGeo proposed using 25lb/cuft CJFill-High Permeability to backfill the stem walls, to bring the building pad up approximately two feet. 25lb/cuft CJFill-HP is provides excellent bearing capacity, but is hand excavatable.
Hand excavatability was important on this project. There was extensive under slab plumbing required, and the lightweight fill couldn’t impede on its installation. A great advantage of 25lb/cuft CJFill-HP is that it provides a clean, stable working surface that easily supports mini and mid-size excavators.
CJGeo mobilized a wet batch cellular concrete plant crew to the site. The crew used silt fence to break the roughly 80 thousand square foot pour into roughly 150CY placements. Each individual pour on this New Jersey lightweight fill project allowed the plumbing contractor to drive their mini excavators on it the following day. The plumbers enjoyed the clean, dry working surface.
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North Carolina Compaction Grouting
The Job
This North Carolina compaction grouting project is located at a military facility in eastern North Carolina. To facilitate the renovation of an adjacent office building, the owner installed eight mobile office buildings. Before the mobile offices were put into use, they settled up to three inches. As a result, the owner had to stabilize the structures before moving any equipment and people into the structure.
The Challenge
The site comprises of sand backfill over native loose sands. The eight mobile buildings bear on masonry piers resting on plastic load distribution pads. The piers and pads are on approximately 6′ centers, spread uniformly throughout the structure. The crawlspace is too shallow to safely enter.
The Solution
CJGeo proposed using CJGrout 35NHV to perform compaction grouting below the piers to stabilize the loose soils. 35NHV is a 3.5lb/cuft rigid polyurethane foam. It performs well for void filling and compaction grouting in wet environments.
Special polyurethane grouting rigs generate CJGrout 35NHV onsite. The rigs have hoses up to 400 feet long, which convey the material from the grouting rigs to the placement area. For this project the 35NHV was injected using sacrificial tubing. The tubing passes through holes in the floor through the crawlspace, to roughly 3′ below the pads.
One of CJGeo’s polyurethane grouting crews was onsite for three days to complete this North Carolina compaction grouting project. CJGeo used rotary lasers to monitor the floor elevation over each pier during grouting. The cutoff criteria was movement of approximately 0.25 inches. Then, a carpentry crew jacked and shimmed the beams after the grouting. Finally, a flooring crew restored the flooring afterwards.
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Coke Gas Pipe Fill
The Job
This coke gas pipe fill project is located in Middletown, Ohio, at Cleveland Cliff’s Middletown Works facility. Middletown Works determined that the coke plant would be more costly to repair than to replace, so elected to demolish the plant.
The Challenge
A demolition contractor working to dismantle parts of the onsite coking plant had to remove approximately 350LF of coke gas pipe. The work area is located in the basement of the coking plant.
Coke gas residuals will spontaneously combust when exposed to the air, but the pipe had to be cut into roughly 3′ pieces to remove it. The pipe fill grout had to:
- completely fill the pipe
- coat the residuals to minimize air exposure
- cut easily
- add as little weight as possible to the pipe sections
The Solution
CJGeo proposed using CJGrout-20SDB to fill the pipes. 20SDB is a 2lb/cuft rigid polyurethane foam, specifically formulated to flow long distances before setting.
CJGrout 20SDB is generated onsite by special polyurethane grouting rigs. The rigs have hoses up to 400 feet long, which convey the material from the grouting rigs to the placement area. For this coke gas pipe fill project, the crew had to run hoses approximately 250 feet into the building, down multiple stair cases. The hoses are lightweight and about 2 inches in diameter, so this isn’t a problem.
One of CJGeo’s polyurethane grouting crews was onsite for two days to complete the project. Once the coke gas pipes were filled, the demolition contractor cut them into 3 foot long pieces with traditional band saws bagged the sections, and removed them from site.
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Pit Fill With Lightweight Flowable Fill
The Job
An abandoned water treatment plant at a federal facility was being rehabilitated and brought back into service. As part of the project, lightweight flowable fill was needed to fill a 12′ deep tank below the building floor needed to be filled before installing a new floor and equipment.
The Challenge
The majority of the pit is below ground water level. The original foundation design used a 62PCF fill density for the pits, presuming they would only ever hold water.
The backfill material also needed to completely encase a number of new micropiles installed for machine bases.
The designer had two competing interests–given the closeness of the water table to finish floor, avoid any buoyancy of the fill material, while using the lightest possible material to avoid inducing any settlement.
The Solution
CJGeo proposed filling the pit with CJFill-UW, at 70lbs/cuft. At 70lb/cuft, there are no uplift concerns, and the material is just barely denser than water, which helps minimize the amount of anticipated settlement. To help ensure future excavatability, CJGeo used a sanded base slurry (as opposed to the usual neat mix slurry) to generate 830CY of lightweight flowable fill material. The 28 day design strength was 150psi. The average 28 day tested compressive strength was 200psi. The removability modulus of the material is 0.75, which means the material is readily excavatable.
Traditional “lightweight” flowable fill is closer to 95lb/cuft. At 150psi, 95lb/cuft material has a removability modulus of 1.18. This is above ACI’s benchmark value of 1 for ease of excavatability.
Batch generation in ready mix trucks was the best method for generating this CJFill-UW. Foam’s sprayed into the drum upon arrival at the site, then the drum blends the slurry & foam as it rotates. The blended CJFill-UW discharges via the chute directly into the placement area. Aerix Industries supplied the preformed foam.
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