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 proposed repair needed to address the settlement by lifting the floor. Due to budgetary constraints, the repair could not disturb the VCT flooring.
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.
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 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 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.
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.
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 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.
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.
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 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.
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.
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.
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.
An area of floor inside of a produce processing facility experienced water intrusion through joints in the floor. Considerable amounts of process water were dumped on the floor each day, and unsealed joints in the floor allowed water to collect under the floor slab. With dynamic loading from material handling equipment, water was displaced through the joint onto the floor. The facility’s health & safety staff was concerned that the water could introduce contaminants to the food processing area.
The proposed repair had to perform well in saturated conditions, allow for near immediate resumption of material handler equipment, and ensure a longterm fix. Since no settlement had occurred, the grout material had to be able to seal the very small voids, displace water, and not exert any lifting forces on the floor.
The material & process also had to be performed at cold temperatures–the facility is maintained at 34 degrees year-round.
CJGeo proposed chemical grouting using a hydrophilic prepolymer grout. Chemical grouting is ideal for saturated environments and helps to ensure complete stabilization and sealing of floors.
A single CJGeo chemical grouting crew mobilized to the site and performed the work in a few hours. The work started after second shift, and was completed in time for the grout to set and tolerate material handling equipment at the start of first shift.
The following day, the facility reported no water extrusion under material handler traffic.
The floor of a 105′ diameter grain bin settled. The floor had a bin sweep installed, that was mounted on the top of the unloading tunnel, which ran down the center of the structure. Where the slab floor butted up to the tunnel walls, the floor had settled 2″ on one half, and 3.5″ on the other half. This caused issues with operating the bin sweep, because it was designed for a smooth, level floor.
The owner’s alternative was to remove the entire floor and pour a new floor. This would have been incredibly expensive, and take a very long time. The only access into the bin was two 2′ wide by 4′ tall doors, located 5′ above exterior finish grade, and 2′ above the bin floor elevation.
Due to the nature of the commodity business, mobilization and completion of the grain bin floor repair had to be fast. Additionally, the repair had to return the floor to its original profile, along with the turned down ventilation trenches in the floor. The extensive turned down ventilation troughs made this floor very susceptible to cracking. The floor was 6″ thick, but then went to 24″ thick at the ventilation troughs. Slabs with non-uniform thickness require extreme care and attention to avoid differential lifting.
The design loads for the floor are approximately 3500psf, so the material used for lifting the floor had to be relatively high strength.
CJGeo proposed polyurethane grouting for filling the voids below the floor and lifting it back into place. The minimum bearing capacity of the proposed materials was 5500PSF, ensuring adequate bearing capacity even under full load.
CJGeo mobilized two polyurethane grouting crews to the site. The work was completed over a period of two days, during which more than 7,000 pounds of polyurethane grout were installed using three reactors running simultaneously. Multiple reactors (pumps) helped to ensure thorough lifting of the slab and the ventilation troughs. The crews that completed this job have collectively performed millions of pounds of polyurethane grouting, ensuring successful completion of this grain bin floor repair job.
25,000 square feet of industrial floor at a military facility settled up to 4 inches and was affected by sub-slab voids. The affected area also included 250 track feet of embedded rail, which was set in an independent, thickened slab section. The building had been used for warehousing, but was being transitioned to light manufacturing/maintenance.
Plans called for an 4” thick overlay slab being installed, with a vapor barrier, over the existing floor. Geotechnical investigation work determined there were extensive voids below the floor throughout the area affected by settlement.
The proposed repair method had to provide adequate bearing capacity for manufacturing, and ensure complete void filling and stabilization.
Polyurethane grouting to fill voids under the floor to stabilize against future settlement. Additionally, in areas which had settled, polyurethane grouting was proposed for correcting settlement.
Due to extensive compressive soil layers below the floor, polyurethane grouting was proposed as an alternative to the specified cementitious grout. The specified grout had an in-place density exceeding 115 pounds per cubic foot. The proposed polyurethane grout had a constrained density of 5.5PCF, yet a bearing capacity exceeding 12KSF.
CJGeo mobilized three polyurethane grouting crews to the facility, with a combined pumping capacity exceeding 5,000 pounds per hour. Nearly 2,000 dime-size injection holes were drilled through the slab, and 5,000 cubic feet of polyurethane grout was installed under the floor & section of embedded rail. Void filling was confirmed by visual inspection (material showing at adjacent drilled holes to injection locations), and slab lift.
In areas which had not settled, 1/8 inches of lift was used as the benchmark change in elevation to confirm complete void filling. Areas which had settled, including the embedded rail sections, were lifted up to 3 inches above the original elevations.
The floating slab floor of a flex space building in Boston, Massachusetts settled up to 9 inches. The tenant was approaching renewal, and had mentioned that the floor settlement was affecting the usability of their space. To avoid losing his long term tenant,
The tenant was an environmental testing company for ships entering the Port of Boston. Daytime staffing levels were high, but there were also continuous nighttime operations to service incoming cargo shipments. The tenant made it clear to the building owner that operations could not be affected at all by any floor repairs.
CJGeo proposed polyurethane grouting using plural component TerraThane to fill voids below the floor and then raise it back to flat. The floor slab settlement resulted from backfill consolidation after building pad preparation. The finished floor elevation was roughly 5′ above the adjacent parking lot, which was at original grade.
Since polyurethane grout is significantly lighter than cement based grouts (4lb/cuft vs 130lb/cuft), using polyurethane grout helps reduce chances of resettlement from applying additional burden on top of the backfill material.
Polyurethane grouting is also exceptionally clean; injection holes are just 5/8″ diameter, dustless drilling is used, and the process is very quiet. This facilitates work in occupied facilities with minimal disruption. All raw material is contained in CJGeo’s trucks, with no concrete truck deliveries, which also allows for easy scheduling of night work or other special schedules around tenant needs.
CJGeo mobilized a two pump polyurethane grouting truck to the site. The first shift was daytime work, and corrected the worst areas of settlement in the warehouse area. The following night, the second and final shift of work was done to correct settlement in the office areas which were unoccupied at night.
The repair was successfully completed with no disruption to the tenant, and the slab was restored to level.