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Polyurethane Grouting Projects

By applying unique solutions to increase the safety and longevity of our environment.

School Floor Leveling

The Job:

The slab floor of a hallway in a middle school settled up to 3.5 inches. A geotechnical study identified voids up to 2.5 inches below the slab throughout the corridor.

The Challenge:

The proposed repair needed to address the settlement by lifting the floor. Due to budgetary constraints, the repair could not disturb the VCT flooring.

CJGeo’s Solution:

CJGeo proposed polyurethane grouting for this slab foundation repair project. Polyurethane grouting uses low unit weight grout, which decreases the chances of future settlement. Polyurethane grouting is performed through 5/8″ holes drilled through the slab. This reduces impacts to flooring, and facilitates fast, efficient repairs.

CJGeo successfully performed this concrete floor repair project in less than a day. By using polyurethane grouting, there was no disturbance to the VCT flooring, and the corridor was able to be used normally immediately afterwards.

Railroad Sinkhole Stabilization

The Job:

During installation of a 42″ jack & bore casing below a three track Class 1 railroad in Martinsburg, WV, ballast started showing in the spoils. Soon afterwards a sinkhole appeared between tracks 2 & 3, 15 feet above the casing. The jack & bore installation was stopped, and the contractor reached out CJGeo requesting an emergency mobilization.

The Challenge:

CJGeo had to mobilize with very little notice, and work had to be performed adjacent to an operational track.

CJGeo’s Solution:

CJGeo mobilized two polyurethane grouting crews, who were on the road in less than an hour. Within four hours of the sinkhole formation, CJGeo was onsite with more than 250CY of material placement capacity.

CJGeo successfully grouted the sinkhole. Rail traffic continued on adjacent tracks, and the face of the bore was restored, allowing the jack & bore operation to safely restart. CJGeo performed this repair using a polyurethane grout with an elastic modulus similar to the existing soil in order to prevent creating a hard spot in the rail.

Tunnel Abandonment

The Job:

A plumbing contractor hand tunneled 140LF of 4’x5′ tunnel under two apartment buildings near Boston, Massachusetts. In preparation for a renovation project, a structural inspection was performed. The structural inspection revealed the slab floors which were tunneled under were not designed as structural slabs. The structural engineer directed the property owner to immediately fill the tunnels to restore structural integrity.

The Challenge:

The tunnel abandonment work had to be completed during the winter, and while one of the two affected buildings was occupied. The non-occupied building was also in the process of asbestos abatement and a full gut renovation.

Due to the plumbing run through the tunnels, an excavatable grout was required. Also, grout had to be low exotherm in order to not affect the new PVC plumbing.

CJGeo’s Solution:

CJGeo proposed polyurethane grouting for the tunnel abandonment. Polyurethane grouting can be performed in any weather, is low exotherm, and can be placed in very thick lifts. The specific grout chosen was a low exotherm bulk void filling polyurethane.

CJGeo mobilized a polyurethane grouting truck with more than 9000 pounds of polyurethane grout, due to the unknown exact volume of the tunnels. During a 8″ snowstorm, CJGeo abandoned both tunnels in a single day. The unoccupied building was grouted via holes drilled through the floor. The tunnel below the occupied building was free sprayed from inside the tunnel. All tunnels were kept under negative pressure ventilation in order to address installation odors.

CJGeo placed 4100 pounds of polyurethane grout into the two tunnels.

Mine Shaft Abandonment

The Job:

The inverted pyramid concrete cap on a Civil War-era coal mine shaft collapsed catastrophically. The mine shaft was located in the middle of a suburban golf course in Richmond, Virginia. The collapse was due to deterioration of timbers lining the shaft through soft sandy soils. The soft sandy soils extended approximately 25VF down to rock. As the timbers deteriorated with time, the lost the ability to support the cap.

The Challenge:

The tunnel shaft was completely full of water, which was approximately 60 degrees. The area around the cap was very unstable, and did not facilitate top-down access over the mine shaft.

CJGeo’s Solution:

The repair was designed around drilling well casing at an angle to intercept the mine shaft at various elevations between the bottom of the cap and socketed down into the underlying rock. 3.5PCF hydroinsensitive polyurethane grout was chosen for its ability to provide the necessary structural support to the cap.

CJGeo performed pre-mobilization testing at our facility in collaboration with the design engineer to ensure that the grout would perform as desired. CJGeo placed polyurethane grout through approximately 15 different injection points, grouting from the top down. The end result was a plug extending at least 5′ into the shaft through rock, ensuring that the shaft through soft soils was completely stabilized.

Office Floor Settlement Repair

The Job:

The slab floor inside of a grain import/export facility office settled. All exterior walls were pile-supported, but the floor was poured as slab on grade. Slab settlement up to 3 inches affected approximately half of the building footprint.

The Challenge:

Over the years the floor settled, extensive cosmetic repairs were done to the walls, including tuck pointing CMU walls, moving/shimming HVAC ducting, and rerouting water lines. Scheduling for the slab foundation repair had to be done around the busy grain season, when the office building was continuously occupied.

CJGeo’s Solution:

CJGeo proposed polyurethane grouting for the settlement repair. Polyurethane grouting is safe, fast, and economical for floor settlement repair.

CJGeo mobilized two polyurethane grouting crews to the facility on a Saturday morning. The entire 4,000 square foot area was lifted over a period of 9 hours, with no 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.

Port Shed Floor Stabilization

The Job:

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, any 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.

CJGeo’s 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. A high density (3.3PCF free rise, 4PCF in place) TerraThane 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.

Commercial Floor Void Fill

The Job:

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 started to open up a 2′ square hole in the floor, and noticed that all the debris was disappearing. After opening the hole it was apparent why–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 operation 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 presumed cause of settlement was consolidation of poorly placed fill, which was primarily construction debris. Lightweight void filling material was required to minimize future settlement of the underlying fill material.

CJGeo’s 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 be filled 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 and installed approximately 4800lbs of 2PCF polyurethane grout over a two day period. CJGeo pulled continuous negative pressure on the void through the floor in order to allow for continuous operation of the facility during grouting. There was zero disruption to the facility’s operations, and the voids were filled completely.

Bridge Approach Polymer Grouting

The Job:

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.

Challenge:

Martins Construction reached out to CJGeo two weeks prior to required mobilization. The project was an accelerated deck replacement and structural repair, and loose soils on both approaches required stabilization using compaction grouting in a manor which would not affect return to service or the bridge deck overlay work.

CJGeo’s Solution:

CJGeo proposed polyurethane compaction grouting using CJGrout 30NHL, which is specifically formulated for improving the bearing capacity of loose soils. Grouting was performed on 4’ centers, at 5’, 10’ & 15’ below grade, until surface movement was detected. Top-down grouting was used to help ensure maximum densification of underlying soils, and approximately 25,000 pounds of grout were used over two mobilizations. 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 and post grouting DCP testing was performed by Schnabel Engineering to quantify the soil density improvement.

Chemical Underpinning

The Job:

Water began to seep through the floor of the shop, break room and bathrooms inside a manufacturing facility. Investigation determined that a water line had broken, and weekend soils below the floor, causing the settlement. Voids were also present.

The Challenge:

The client’s primary concern was addressing the stability of the area without affecting normal usage.

CJGeo’s Solution:

CJGeo proposed chemical grouting to stabilize the weakened soils, along with polyurethane grouting to fill voids. Previous repairs to address floor settlement had been completed, so a hydroinsensitive undersealing polyurethane grout was used to ensure stability without lifting the slab.

RCP Pipe Sealing

The Job:

The asphalt parking lot over a 300′ run of 54″ RCP culvert kept collapsing. The public works department of locality determined that the joints between the 4′ sticks of pipe had not been properly gasketed or seated during installation. The pipe saw continuous flow of a small stream, entering at an end wall and discharging into a box culvert which crossed 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, which had to be 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 sewer 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.

CJGeo’s Solution:

Polyurethane grouting to 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 NCFI high density, hydroinsensitive 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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