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