Yonkers Polyurethane Grouting
The Job
This Yonkers polyurethane grouting project is located in Yonkers, New York. The project is part of a renovation of a multi-tenant strip center into a single discount grocery tenant.
The Challenge
During construction, someone on the general contractor’s team thought that areas of the floor sounded hollow. Tapping on the floor, it sounded like a drum. The contractor reached out to CJGeo, and we recommended performing a few cores in the hollow sounding areas.
Coring revealed extensive voids in two areas of the building footprint. Both were along the side exterior walls. In one area of the floor, the voids were up to 4′ deep. The apparent cause for the voids was a longstanding problem with below slab plumbing when the space was a deli and dry cleaner.
The Solution
After the cores were used to confirm the size and extent of the voids, CJGeo recommended CJGrout 20SDB geotechnical polyurethane grout to fill the voids.
CJGrout 20SDB is ideal for filling large voids below floors because it is low exotherm. Many foams used for polyurethane grout are not well suited for filling very large voids.
A plumber installed new sanitary lines below the floor after CJGeo completed the void filling. The void filling only took a single day onsite. It’s important to fill voids first so that cutting new plumbing trenches doesn’t cause catastrophic, unexpected settlement.
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Flooded Shaft Grouting
The Job
This flooded shaft grouting project by CJGeo is located outside of Washington, DC at a data center site. As the 60″ microtunneling machine was entering the retrieval shaft, a piece broke off of the secant pile wall, and tore the seal. This resulted in water infiltration of around 600 gallons per minute into the shaft. The machine was recovered, but the shaft filled with nearly 15 feet of water in a matter of hours.
The casing crown has roughly 20 feet of cover, and is about 15 feet below the ground water level. The ground in the area is a mix of clays and sands. The tunnel is primarily in the underlying fractured rock. For the last 30 feet of tunnel before the secant pile receiving shaft, the tunnel is in a mix of weathered rock and sandy clay.
The Challenge
Having used CJGeo in the past to address high volume leaks into shafts, the tunneling contractor reached out to CJGeo for this flood shaft grouting problem. The primary constraints were:
- time – the project was already behind schedule
- water management – any groundwater was considered contaminated
Typically, grouting a leak such as this would be as simple as throwing bigger pumps into the shaft, dewatering it, then grouting the leak from inside the shaft. However, because of the costs associated with treating potentially very high volumes of water at this site, this wasn’t an option.
The Solution
CJGeo proposed, and then successfully performed, a two stage grouting program. Primary grouting was done using CJGrout 35NHV61 geotechnical polyurethane on a Saturday. The CJGrout 35NHV61 was installed immediately behind the secant pile wall through three holes drilled from the surface to intercept the over cut. Grout injection through these holes resulted in grout return to the retrieval shaft. Off gassing also showed up at the launch shaft. This indicates that the rapid inflow of water during the flooding event had washed out some of the mud in the over cut.
After completion of the plural component primary seal injection, CJGeo dye tested the primary grouting program. This was done through Tube-A-Manchette grout pipes installed using sonic drilling along the tunnel alignment, further out from the shaft. No dyed water returned to either shaft.
The following day (Sunday), CJGeo performed permeation grouting using colloidal silica through the TAM grouting tubes. This secondary grouting program served two purposes:
- seal any rock fractures that weren’t penetrable by the higher viscosity plural component polyurethane grout
- replace any overcut mud washed out during the initial flooding event
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Underground Storage Tank Fill
The Job
This underground storage tank fill project by CJGeo is located at a food manufacturing facility near Harrisonburg, Virginia. The tank is 30 thousand gallons, and designed to store diesel to feed backup power generation for the facility. As part of an equipment upgrade, the tank is no longer in use, and had to be filled.
The Challenge
The best way to address unused underground storage tanks that aren’t removable is to fill them. If left empty and out of mind, abandoned empty tanks can cause serious problems, such as sudden collapse, which can significantly affect operations. Unfilled, out of use tanks can also accumulate groundwater, leading to potential environmental liabilities.
The Solution
CJGeo proposed 30lb/cuft CJFill-Ultra Lightweight (CJFill-UL) to fill the tank. CJFill-Ultra Lightweight is easily hand and machine excavatable to ensure that when the tank is removed in a few years that it’s not difficult.
While easily hand excavatable, CJFill-Ultra Lightweight still provides more than adequate compressive strength. In this case, total loads were just a few hundred pounds per square foot, whereas the CJFill material provides more than 17ksf of unconfined compressive strength. The American Concrete Institute publishes a removability modulus calculation which helps to quantify the ease of removal of controlled low strength materials, read more about it and how it relates to cellular concrete here.
It took CJGeo less than an hour to completely fill this tank. Confirmation of complete fill was uniform material venting from the tank vent ports.
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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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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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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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