1 Mile 36″ Waterline Abandonment
THE JOB
CSX crews were surfacing the mainline track in Baltimore when the tamping equipment struck an object immediately below the ties. Investigation revealed that it was a manhole associated with nearly 6000LF of 36″ water main primarily running immediately below the tracks. The municipality relocated the waterline. Next, they had to fill the pipe from just two intermediate points. There were three sections of pipe; 1200LF, 1600LF & 2900LF. Various potential solutions for the watermain abandonment included:
- threading sacrificial tubing and grouting on the way out, and
- pumping flowable fill from the manholes,
However, none were economical or could guarantee a pipe abandonment below the railroad.
THE CHALLENGE
The project designer, OBG, identified cellular concrete as a potential solution to the problem and reached out to CJGeo to determine its feasibility. CJGeo confirmed the appropriateness of cellular concrete and set out to create a grouting plan. Coordination between the utility contractor and slurry provider (the site was too small to set up a batch plant) was crucial to ensure that the runs of pipe were all successfully filled in a single shot each. With train frequencies of 3-4 per hour, if the operation didn’t work and the pipes were only partially filled, there was no opportunity to create intermediate access points to finish grouting a section of pipe.
Based on the required bearing capacity and production requirements, CJGeo proposed 22lb/cuft CJFill-Ultra Lightweight cellular concrete for abandonment. With a 25psi break strength at 28 days, the mix provided the required strength, met the CSX utility occupancy standard for abandonment, and maximized expansion in order to ensure the longest run, which required nearly 1000CY of the finished product, could be grouting in a single shot.
THE SOLUTION
CJGeo mobilized a 150CY/hour cellular concrete crew to the site and performed the two shorter runs the first week. The project was broken into two different weeks due to the criticality of ensuring the longest run was filled completely without issue. The first two runs allowed CJGeo, the GC, railway flaggers, railway operations, and the slurry provider the opportunity to work out any kinks in operations during the lower risk placements.
The following Tuesday, starting at 0600, Chaney Enterprises delivered the first of 24 loads of slurry. Overall, the work took three days. CJGeo generated & pumped a total of 1710 cubic yards of cellular concrete to successfully complete the waterline abandonment.
This project would have been much easier using a mobile batch plant, which we now have three of.
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Facing a similar challenge to this waterline abandonment project? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
Railway Grade Crossing Repair
THE JOB
112 track feet of crossing panels settled, and needed grade crossing repair. This caused the adjacent asphalt pavement to fail. The crossing ran diagonally across the highway. The road was graded so that the crossing was the primary flow path for surface water.
The crossing had already been replaced twice. The last replacement used flowable fill as the base material. The crossing panels experienced approximately 1 inch of deflection with highway traffic. There were also 4-inch voids below the panels.
With highway traffic from heavily-loaded vehicles, the crossing deflected enough to squirt water three to four feet in the air. This water pumping action actively pumped the subbase material from under the crossing.
THE CHALLENGE
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 the repair was designed around high service loads for heavy haul rail traffic.
THE SOLUTION
High-density polyurethane grouting using CJGrout 48NHL for this grade crossing repair. CJGrout 48NHL is designed specifically for rail and airfield grouting work.
CJGeo modular grade crossing repair crew filled the voids and corrected settlement in less than a day. Asphalt patching was done concurrently with polyurethane injection. The entire repair took less than one day. The roadway and rail opened up immediately after the repair.
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Facing a similar challenge to this railway grade crossing repair? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
Urban Grade Crossing
THE JOB
32 track feet of grade crossing panels settled. This caused the adjacent asphalt pavement to fail and caused tripping hazards at the adjacent pedestrian sidewalk. The grading in the area was relatively good, however, the adjacent ballast was fouled, which caused water to accumulate under the crossing panels and wash out the sandy subbase material. The crossing had been replaced recently. Due to the urban, primarily passenger automobile traffic, there was a 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 two of the 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 CHALLENGE
The repair had to allow immediate vehicular traffic to facilitate a single-lane closure. The repair also had to allow for immediate resumption of rail traffic. The crossing served as a sand mine, so the settlement correction repair was designed around high service loads for heavy haul rail traffic.
Due to the scheduling constraints of the railroad, the repair method had to tolerate the potential for rail traffic during the repair.
THE SOLUTION
High-density polyurethane grouting to stabilize and lift the affected modular grade crossing panels, using CJGrout 48NHL.
Epoxy-augmented patching of the spalled areas to restore a smooth walkway for pedestrians.
CJGeo modular grade crossing repair crew filled the voids and corrected settlement in less than a day. Asphalt patching was done concurrently with polyurethane injection. The entire repair took less than two hours. 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.
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Facing a similar challenge? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
Warehouse Floor Lifting
THE JOB
25,000 square feet of the industrial floor at a military facility settled up to 4 inches and was affected by sub-slab voids. This warehouse floor lifting project 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.
There were extensive voids below the floor. The voids were located with GPR, and confirmed with cores. Because the floor had cracked extensively as it settled, the designer called for a 4″ un-bonded overlay after stabilization.
THE CHALLENGE
The proposed repair method had to provide adequate bearing capacity for manufacturing and ensure complete void filling and stabilization.
THE SOLUTION
CJGeo provided a value engineering proposal to use geotechnical polyurethane instead of cementitious grout. The VE proposal was based on the following:
- lower unit weight, so less likelihood of causing additional settlement
- adequate strength to ensure uniform load transfer to the underlying soils
- simplified logistics into a secure facility (all material delivered in just two truckloads)
The specified grout had an in-place density exceeding 115 pounds per cubic foot. The proposed polyurethane grout, CJGrout 40NDV, has 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. CJGeo crews injected the CJGrout 40NDV through nearly 2,000 dime-size holes drilled in the slab to complete this concrete lifting project.
The cutoff criteria for void filling was cross-hole communication or 0.1 inches of lift. The settled areas of floor raised an average of three inches. The embedded track area raised up to four inches.
It took CJGeo fewer than 10 days to complete this warehouse floor lifting job. Because the material cures to 95% within a few minutes, the overlay preparation crew worked a day behind the polyurethane grouting crews.
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Facing a similar challenge to this warehouse floor lifting project? Give us a shout or shoot us a text. Click the state marker for the location of the project for contact info for the appropriate rep.
