Maryland Concrete Lifting
The Job
This Maryland concrete lifting project is located in Frederick, Maryland. The project is for the MARC system, on tracks also used by CSX.
The Challenge
MARC’s Brunswick Line includes a spur to Frederick, which utilizes a freight track that also serves multiple industrial sites, including quarries and concrete plants. As it winds through an industrial area towards the Frederick station, the line crosses multiple arterial roadways. As Frederick grows, traffic is increasing significantly with both cars and industrial truck traffic.
At two crossings, bellies have developed in the precast modular grade crossings. Water collects at the low spots, which then reduces bearing capacity of the base, causing deterioration of the adjacent asphalt pavement. This deterioration causes spalling of the panels, and ride quality problems for motorists.
The Solution
CJGeo’s rail grouting experience includes dozens of precast modular grade crossing stabilization projects. Working with the rail system’s on-call MOW contractor, a CJGeo polyurethane grouting crew grouted each of the two crossings in a day, each.
CJGeo uses CJGrout 48NHL, which is specifically formulated for high dynamic load applications. 48NHL provides multiple factors of safety from a compressive strength perspective, but is slightly elastomeric, which makes it much more durable than mudjacking or traditional cementitious pressure grouting grouts sometimes used to stabilize modular grade crossings on a temporary basis.
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Basement Wall Load Reducing Fill
The Job
This basement wall load reducing fill project is located in Lexington, Virginia, on a campus of Washington & Lee University. The scope is part of a new academic building construction project. The building will house the Williams School of Commerce, Economics & Politics.
The Challenge
The building is on a sloping site. The front of the building will be slab on grade, and the back half of the building will be a walk-out basement level. The transition between the two floors is an approximately fifteen foot tall wall with two 90’s.
The basement wall is designed to be braced by the floors and building. However, the floors & building couldn’t be built until the wall backfill was in place. In order to backfill the wall, it would need load reducing fill, or it would need temporary bracing.
The Solution
A structural engineer recommended the general contractor reach out to CJGeo about backfilling the wall with CJFill-Ultra Lightweight low density fill. Working with the structural EOR, geotech EOR & general contractor, CJGeo developed a backfilling plan that would allow backfilling the wall over three days while eliminating the need for temporary bracing.
CJGeo poured three lifts, each about 4.5′ deep. A dry batch process plant running at up to 200 cubic yards per hour backfilled the wall in three days.
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Low Density Bridge Underfill
The Job
This low density bridge underfill project is located on Interstate 95, in Philadelphia, Pennsylvania. The scope is part of a large widening and reconstruction project. The bridge is located over Carver Street, just south of the Tacony-Palmyra Bridge.
The Challenge
As much underfill as possible had to be in place prior to the bridge demolition. Otherwise, it would have been impossible to demolish the deck, beams & other structures during a limited closure. There are also multiple underlying utilities which would not tolerate the nearly 5ksf of additional dead load from using traditional flowable fill.
The Solution
In order to fill up to the bottom of the beams, CJGeo designed a mass fill placement plan that stepped in at a roughly 1.5H:1V slope. CJGeo batched CJFill-Ultra Lightweight with a 40psi at 28 day minimum compressive strength using the dry batch process onsite, and placed at times more than 1,000 cubic yards per day.
Once the CJFill-UL was in place to complete this low density bridge underfill, the customer was able to demolish the bridge and beams, only need to bring in a few feet of crushed stone for the pavement base, and then pave the roadway to restore traffic. This was performed during an accelerated closure to minimized traffic disruption.
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Lightweight MSE Wall Backfill
The Job
This MSE wall lightweight backfill project is located near Chester, Virginia. The MSE wall is part of a ramp reconfiguration and lengthening project at the interchange of Rt 10 and Interstate 95. Specifically, this ramp is from westbound Rt 10 to northbound Interstate 95.
As part of the ramp lengthening and realignment, the ramp needed to shift out onto an existing embankment.
The Challenge
There was insufficient right of way to widen the embankment without acquiring additional right of way. In order to shift the road without acquiring additional land, the geotechnical engineer of record, Schnabel Engineering, recommended to building a mid-slope MSE wall. The wall design includes a lightweight reinforced and retained zone to eliminate any net change in load. Effectively, when the slope is notched for the MSE wall construction, the difference in fill density allows for increased height.
The Solution
The existing soils were rough 125lb/cuft, and the CJFill-Ultra Lightweight backfill is 30lb/cuft. This allows for two additional feet of fill depth for every foot of undercutting. The final MSE wall lightweight backfill design included a 140psi minimum 28 day compressive strength (ASTM C495).
It took three lifts to backfill the wall, which was at most eight feet tall, and roughly 150 feet long. A composite drain on the slope addresses and water migration through the soil slope, and ties into a gravel bed at the base of the CJFill-UL load reducing fill.
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Box Culvert Void Filling
The Job
This box culvert void filling project is located near Fredericksburg, Virginia. The Virginia Department of Transportation owns and maintains the structure, which conveys a stream under a rural divided highway. As part of a rehabilitation project, extensive cracking in the structure (a double barrel six foot by six foot box), was being patched with repair mortar, and some cracks epoxied.
The Challenge
At the start of project, the general contractor discovered extensive voids outside of the structure. These voids were allowing significant amounts of the stream flow outside of the box culvert (piping). This was cause for concert regarding the specified repair mortar application and epoxy injection.
The general contractor reached out to CJGeo about filling the voids with grout prior to the patching and repair operation.
The Solution
CJGeo proposed grouting all the voids outside of the box culvert with CJGrout 35NHV61. 35NHV61 is a hydro-insensitive, structural polyurethane grout. Its NSF61 potable water certification makes it excellent for work on drainage structures.
The owner, Virginia’s Department of Transportation, required water testing before, during and after grouting. This water testing specifically looks for MDI. All of the water testing, which was performed by a third party environmental laboratory, found zero MDI in any of the water samples.
It took three days onsite to complete the grouting. Some hairline cracks that were still damp after the bulk box culvert void filling work. CJGeo grouted these cracks with a hydrophilic chemical grout to make them completely dry.
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Facing a similar challenge to this box culvert void filling project? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
SOE Closure Manchette Grouting
The Job
This SOE closure Manchette grouting project is located in Alexandria, Virginia. It is part of the RiverRenew project, a large CSO project.
The Challenge
As part of this project, a diversion structure and drop shaft were being installed to pull flow off of an existing sewer tunnel. The box tunnel is around 8′ wide. The SOE will facilitate installation of the diversion chamber. Excavation within the SOE called for closing the gap between slurry wall panels. This is to be done under the existing structure with steel lagging.
However, the closure is below ground water table. The “marsh” deposits soils require stabilization prior to excavation. The conceptual design from the owner called for permeation grouting tied into an underlying clay layer. The clay layer is approximately 50′ below existing grade.
The Solution
CJGeo proposed performing the permeation grouting to cut off ground water flow and stabilize the soils for excavation using an acrylic grout. Due to the relatively deep required depth, traditional percussion driven installation tubing wasn’t possible.
To ensure accurate placement at depth, CJGeo used the TAM grouting method. TAM grouting, or Tube-a-Manchette, uses special grout casing installed by drilling to grout through.
CJGeo performed this SOE closure Manchette grouting work over a period of two weeks.
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Massachusetts Lightweight Fill
The Job
This Massachusetts lightweight fill project is located at Boston’s Logan International Airport. It is part of Logan Forward continuing improvements to the airport.
The Challenge
As part of this project, the general contractor installed two cast-in-place barrier walls. The space between the barrier walls is between four and nine feet. The walls are curving, have non-vertical faces, and bear on a curving, non-horizontal existing podium slab. The gap between the walls needed to be filled in order to pour a housekeeping slab spanning between the walls.
This work is all on an existing podium structure. So, the fill density between the two walls had to be as low as possible.
The Solution
CJGeo proposed filling between the two walls with CJGrout 20SDB. 20SDB has a similar density and compressive strength to typical expanded polystyrene (EPS, or Geofoam) blocks. However, unlike geofoam blocks, 20SDB:
- is pumped, so doesn’t require trimming, and fits to any shape
- expanded onsite, so logistics are significantly simpler
- cures within a few minutes, so is still quick
- not affected by petroleum products
A CJGeo polyurethane grouting crew took a single shift onsite to install the 64 cubic yards of CJGrout 20SDB. The general contractor began installing the topping slab the next day.
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Facing a similar challenge to this Massachusetts lightweight fill project? Give us a call or send us an email by clicking on the state marker to locate the Preconstruction Manager that services your area.
Detroit Michigan Annular Space Grouting
The Job
This Detroit Michigan annular space grouting project is located near Van Dyke Avenue & 8 Mile Road. The project owner is Great Lakes Water Authority, and the project is part of the PCI-4 rehabilitation.
The Challenge
As part of the rehabilitation of this large diameter sewer, three different liner systems had to be installed. The longest section of single liner type is approximately 800 linear feet. The concrete sewer’s inner diameter is approximately 17.5 feet. The outer diameter of the liner that the installer subcontracted the annular space grouting to CJGeo on is approximately 16.5 feet.
Based on the theoretical average inside diameter of the existing sewer, the annulus is almost exactly one cubic yard per linear foot.
The Solution
The pipe runs at full charge at least once per day, so there was a high likelihood of accumulated water in the annulus. To displace this water and ensure consistent bearing of the pipe, CJGeo proposed 75lb/cuft CJFill-Under Water. While this density of CJFill cellular grout significantly exceeds the 300psi at 28 day compressive strength requirement, it facilitates displacing solids from the annulus.
To help manage buoyancy, once the first lift was in place, the wet cast density of the cellular concrete on this Detroit Michigan annular space grouting project was reduced to 45lb/cuft CJFill-Standard. Reducing the wet cast density significantly reduces uplift, which allows taller lifts.
CJGeo used an onsite dry mix batch plant to generate the cellular concrete and pump it up to five hundred feet in the sewer line.
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Michigan Pipe Abandonment
The Job
This Michigan pipe abandonment project is located in Grand Rapids, Michigan. As part of the Coldbrook Pumping Station decommissioning project, 2250LF of 48″ pipe, and 2300LF of 60″ pipe were specified for grout filling.
The Challenge
The primary challenge for the general contractor on this project was the sheer volume of abandonment grouting. The project also had a significant amount of smaller diameter pipe, but it was in shorter runs, so was easy for them to self-perform with flowable fill.
The Solution
CJGeo proposed using 25lb/cuft CJFill-Ultra Lightweight cellular concrete. CJFill-Ultra Lightweight can be pumped thousands of feet per placement. This eliminates the need for most intermediate access points. Placement points on this project were in the driveway of a fire station, next to a new riverwalk project, and also on the grounds of the pumping station.
CJGeo mobilized a dry batch cellular grout plant to the site, and made around 200 cubic yards per hour of CJFill-Ultra Lightweight to finish this Michigan pipe abandonment project. Each run was up to 2500 feet long at a time. The abandonment work took five days onsite. By utilizing on site dry batching, a snow storm and cold overnight temperatures did not affect the work.
After the crew was completed with this work, they moved to Detroit to perform annular space grouting on a 17′ diameter CSO outfall structure.
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Pregrouting for Hand Mining
The Job
This large CSO project in Alexandria, Virginia required pregrouting for hand mining. The hand mining was to install a new pipe below an existing influent tunnel, which is on piles. The hand mined tunnel was to connect two a secant pile shaft to a slurry wall pit, which are roughly 25′ apart.
The Challenge
The challenges on this project included:
- no drilling allowed without pre-probing
- 3′ thick secant pile walls
- unknown exact pile support layout of influent tunnel
- fully saturated soils
- potential debris in backfill under existing influent tunnel
The Solution
CJGeo proposed performing the permeation grouting using acrylate. Acrylate is exceptionally low viscosity, so well suited to the organic, fine-grained soils. Previous permeation grouting on the project was done with acrylamide. However, acrylamide is neurotoxic and carcinogenic, so the owner was happy to learn about acrylate, which has very similar properties, but is not neurotoxic or carcinogenic.
To avoid drilling, CJGeo developed a pushed/driven probe grouting installation. This approach uses 1/2″ diameter steel tubing driven to depth, and then grouted through during extraction.
The 3′ thick secant pile walls didn’t pose too much of an issue, clearance holes were drilled with hand-held percussion drills.
Drilling wasn’t allowed. The owner and design team were concerned about potentially hitting and damaging the pile foundation. Because there was the potential for debris, there would be no way to distinguish debris from a pile until it was potentially too late. By using groutable probe rods, CJGeo avoided all of this risk.
The fully saturated soils had relatively low permeability, and the site was constrained on two sides by the existing SOE structures. Performing permeation grouting when below the water table you’re limits the placement rate by the ability to displace the existing groundwater. Because of the water-tight walls on two sides of this pregrouting for hand mining application, take was slower than originally anticipated.
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