Starting immediately after construction was completed, the slab on grade floor within the cafeteria, loading dock and kitchen at a corporate headquarters building in Pittsburgh, Pennsylvania settled. Over the course of 12 years, the owner had four different grouting companies attempt to address the problem. Lime slurry injection below the slab was disruptive, and settlement always resumed shortly thereafter.
Compaction grouting was performed in one area, but was so disruptive that despite the fact that it was the only method where settlement didn’t resume, the owner kicked the contractor off the site after nearly four months of not having access to their executive dining room.
Settlement progressed over time to be as much as four inches, affecting nearly 20,000 square feet of floor. A general contractor retained by the owner reached out to CJGeo about performing low impact grouting to address the settlement.
Because settlement affected the entire kitchen, food prep, serving and majority of the dining areas, repairs had to be facilitate continuous use of the facility. Additionally, due to 24 hour staffing of the facility, noise had to be limited, and there was zero tolerance of dust.
Video inspection of the extensive gravity sanitary and floor drains below the floor revealed six defects, including a 2″ offset in a sanitary drain line for a 6 stall restroom.
CJGeo performed 17 DCP tests to determine the depth of uncontrolled fill, which was the presumed cause of settlement. DCP testing showed pockets of WOH fill down to 35′ below finish floor, and voids ranging from 2″ to 18″ immediately below the floor.
Over the course of 7 nights onsite, CJGeo crews installed 12,000 pounds of CJGrout 20SDB into voids immediately below the floor, and 53,000 pounds of CJGrout 35NHV61 for polyurethane compaction grouting. Compaction grouting was performed up to 35′ deep, but to an average depth of 15′ over the entire area.
All work was completed off hours. As soon as the kitchen shut down for the evening, CJGeo crews swung into action, grouting through the night until wrapping up in time for the food prep crews to get ready for breakfast at 0500.
To facilitate grouting under four walk-in freezers and refrigerators, over the course of a 24 hour shift, all cold contents were moved to reefer trailers, CJGeo grouted to 30′ under the freezers and refrigerators, which were then immediately turned back on, and then refilled.
Through careful coordination with multiple operational divisions for the owner, general contractor, flooring restoration contractors, plumbers, and remediation contractors, CJGeo successfully completed the project under budget and on time.
When the operators of a tire and auto shop noticed a sinkhole developing next to their building, they weren’t sure what to do. After an employee crawled into the hole and discovered that he could stand up underneath their building, the owner reached out to the city. City crews determined that a 20″ VCP combined sewer & storm pipe had collapsed under the structure, roughly 25′ below grade.
An on call contractor for the city installed a new manhole and rerouted the pipe around the building, but addressing the sinkhole was out of their businesses’s scope. The project manager reached out to CJGeo, who visited the site and recommended DCP testing to better quantify the extent of the problem.
DCP testing showed that outside of the large hole on the surface, there was little deep disturbance. Working with the city’s consulting engineer, CJGeo developed a grouting plan to install two different CJGrouts; 20SDB in the bulk voids near the surface, and 35NHV61 for soil grouting to address voids within the underlying ground near the failed sewer line.
While onsite for just 6 hours, a CJGeo crew completed the work with zero disruption to the businesses’s operations.
With an annual throughput capacity of 48 million tons, Norfolk Southern’s Pier 6 at Lamberts Point in Norfolk, Virginia is one of the largest coal transloading facilities in the world. As a round-the-clock facility built around precision logistics, there’s little tolerance for disruption or downtime.
When two sinkholes opened up at the end of Pier 6 adjacent to the bulkhead, railroad personnel reached out to an onsite maintenance contractor. Steel plates were installed to provide temporary protection while a long term solution could be implemented.
CJGeo performed DCP testing at the site in order to quantify the depth of voids below the pavement adjacent to the sinkholes. The DCP testing showed that in addition to large voids visible from the sinkholes immediately below the pavement, there were large pockets of voids down to 15’ below the surface.
CJGeo crews then used CJGrout 35NHV61, a hydroinsensitive, NSF-certified geotechnical polyurethane to fill all voids and restore stability to the area. The grouting work took five hours onsite to install 3400 pounds of material, with zero disruption to operations.
As part of a 24 lane mile mill & pave rehabilitation on the Pennsylvania Turnpike, slab stabilization was required. The Turnpike’s specification for stabilization is either liquid asphalt or polyurethane.
In order to keep MOT in place continuously, work had to be done 24 hours per day. Due to work on three bridges within the repair area, undersealing also had to be phased.
CJGeo proposed undersealing with CJGrout 40NHL, a 4.0 lb/cuft free rise polyurethane grout formulated specifically for undersealing thick pavements in transportation environments. 40NHL is hydroinsensitive, so performs well in wet environments, as confirmed with NYSDOT GTP-9 testing.
Using a double gang drill and single grout truck, CJGeo crews undersealed up to 1.8 lane miles per shift. Drilling was completed at night, and grouting during the day, to allow the general contractor to keep MOT in place continuously.
Heavy haul freight (silica mine), urban street by short line
100 track feet of crossing panels settled. This caused the adjacent asphalt pavement to fail, and caused tripping hazards at the adjacent pedestrian sidewalk. The crossing ran diagonally across the roadway. The crossing had been replaced twice in the past. The last replacement used flowable fill as the base material. Due to the urban, primarily passenger automobile traffic, there was little deflection of the crossing panels from highway traffic. However, there were up to four inches of deflection from rail traffic loading.
The deflection from rail traffic loading caused the top edges of adjacent panels to be in compression with each other. This caused extensive spalling of the surface, which affected approximately 8 panels. While not a functional problem for panel integrity, the spalled areas were within the sidewalk portion of the crossings, and therefore posed tripping hazards.
The repair had to allow immediate vehicular traffic to facilitate a single lane closure that was flipped halfway through the repair. The repair also had to allow for immediate resumption of rail traffic. The crossing served a sand mine, so repair was designed around high service loads for heavy haul rail traffic.
Due to scheduling constraints of the railroad, the repair method had to tolerate the potential for rail traffic during the repair.
CJGeo modular grade crossing repair crew filled the voids and corrected settlement in less than a day using polyurethane grouting. Asphalt patching was done concurrently with polyurethane injection. The entire repair was completed in less than one day. The roadway and rail opened up immediately after the repair. Traffic control was done to accommodate pedestrians and roadway traffic.
Two trains passed through the crossing over the panels being repaired during the repair. This did not affect the integrity of the repair.
12 tub-style grade crossing panels developed a 2.5″ belly on a heavy haul industrial scrap short line. The railway’s FRA inspector directed the railway to address the settlement of the crossing panels to bring the crossing geometry back into compliance. Along with being non-compliant from a track geometry perspective, accumulation of water below the panels was causing deterioration of the adjacent asphalt pavement.
The belly only affected one travel lane of the roadway, but repairs had to not affect the other lane, so that traffic could be maintained to the adjacent industrial properties. Due to rail traffic schedules, the repair had to allow for rail traffic during the repair.
CJGeo crews performed the crossing repair in a single day, using polyurethane grouting. During the repair, two trains utilized the crossing.
The 8′ long panels of tub style grade crossing settled. As a result, a speed restriction was placed on the crossing, which affected passenger schedules. Three panels were affected, and the belly in the slabs was approximately 2 inches. Slight deflection with heavy truck traffic was noted, and significant deflection with rail traffic was present.
The repair had to be completed in just a few hours, to avoid disruption to rail traffic. The repair had to allow for immediate resumption of rail traffic, and tolerate tamping of the adjacent truck during the repair. Additionally, the tub crossing repair had to be done in a manner which did not disturb the adjacent asphalt pavement.
High density geotechnical polyurethane grouting to stabilize and lift the affected modular grade crossing panels. Geotechnical polyurethane grouting is far superior to mudjacking, in that the process is faster, and can more easily ensure a complete filling of voids under the crossing panels. Lifting precision of less than 0.1 inches is standard.
A CJGeo modular grade crossing repair crew filled the voids and corrected settlement in a few hours. During the tub crossing repair, tamping was done by the rail system to address settlement of the adjacent track.
Settlement and deflection were affecting an eight panel modular grade crossing in an industrial driveway. The crossing was used by both commuter rail and freight. Settlement of modular grade crossing was causing spalling of the panel edges due to more than 2 inches of deflection from rail traffic.
The repair had to quickly and thoroughly address the voids and settlement of the panels to avoid disruption to commuter revenue traffic. A daily window of four hours between last morning and first afternoon commuter traffic was available for the repair.
Due to scheduling constraints within the busy Washington, DC metro area freight market, the repair area had to be openable to freight traffic on 15 minute notice any time during the repair.
High density polyurethane polyurethane grouting to stabilize and lift the affected precast grade crossing panels. Polyurethane grouting is an effective repair for both void filling to address deflection, and also lifting panels to correct settlement.
The crossing was repaired and returned to service without disruption to commuter or freight rail service.
A suburban grade double crossing was rebuilt to address poor drainage infrastructure in the area. This included installing two different culverts adjacent to the crossing panels, and then resetting all of the panels which had to be removed for the culvert installation. During routine track inspections, the panels showed signs of deflection up to one inch with rail traffic. The system’s track division was concerned that pumping of the crossing panels would lead to destabilization of the base, and settlement. At the lower elevation end of the crossing, there was extensive evidence of sub base material being pumped out from under the crossing within two weeks of the crossing reconstruction. 368 track feet were affected.
Work had to be completed during non-revenue hours, between 0200 & 0430 over two nights. There was also a high probability of the voids below the panels being waterlogged.
High density polyurethane grouting to stabilize the grade crossing panels. Specially-formulated hydro-insensitive void filling (high-mobility) grout was proposed in order to ensure complete filling of voids below the panels, whether waterlogged or dry.
CJGeo successfully stabilized the crossing during the two night work period.
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.