Seawall curtain grouting
The Job
This seawall curtain grouting project is located at a secure facility in North Carolina. It is owned and maintained by the federal government.
The Challenge
The facility is located along a tidal waterway, and has a pre-cast concrete panel seawall protecting it from the adjacent waterway. The soils in the area are beach sand. Numerous sinkholes developed over time at the top of the seawall, which is just over half a mile long. The structure extends up to 17 feet from the cast-in-place cap down to the mud line, with mean high tide roughly six feet below grade. In other areas, the mud line is as close as five feet to below water. The seawall retains an airfield taxiway, runway, and extensive sensitive other infrastructure elements.
The original design for the seawall repair called for performing jet grouting along the entire length of the wall. This caused concerns from an environmental perspective, due to the difficulty in containing highly mobile material behind the wall, and also the equipment required for jet grouting, given extensive sensitive structures adjacent to the wall.
The Solution
CJGeo worked with the general contractor to analyze two different alternative repairs:
- permeation grouting with an acrylic grout
- curtain grouting with geotechnical polyurethane
Based on cost, timeline, and environmental concerns, CJGeo and the general contractor determined that curtain grouting with geotechnical polyurethane was the best alternative to jet grouting. Fundamentally, curtain grouting effectively coats the backside of a wall or structure with plastic, kind of like a waterproofing membrane, but without having to excavate.
Working together, the solution was presented to the owner. The owner determined that the value engineer alternative was preferable to the original design based on:
- water quality risk management – CJGrout 22SHV is certified for potable water contact, and does not contain PFAS. CJGrout 22SHV does not contain any cement, which can quickly change the pH of water, affecting aquatic life
- top side footprint – no drilling equipment is needed in this case. This eliminates obstructions for the airfield operation, and eliminating surface disturbances and surcharge loads on the wall
- cost – the value engineer alternative was accompanied by a savings of approximately $1.7 million
CJGeo mobilized a single polyurethane grouting crew to the site. Over a period of three months, CJGeo successfully performed the seawall curtain grouting work.
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Paved Slope Void Filling
The Job
This paved slope void filling project is located in Interstate 95, near Rocky Mount, North Carolina. The work is part of a bridge rehabilitation for the North Carolina Department of Transportation.
The Challenge
One of the bid items for the project is filling voids below the paved slopes protecting the embankments below the bridge structures. There are two bridges; each carrying two travel lanes over a set of railroad tracks and a rural roadway.
The slopes are quite steep; effectively 1:1. Specifications call for a 3lb/cuft geotechnical polyurethane for the void filling.
The Solution
The general contractor awarded the polyurethane grouting work to CJGeo due to our extensive experience performing geotechnical polyurethane grouting on transportation projects.
CJGeo mobilized a single polyurethane grouting crew to execute the paved slope void filling work. The crew used CJGrout 35NHV geotechnical polyurethane to completely fill all of the voids. Cutoff criteria for the project was cross-hole communication.
Due to the very steep slope, CJGeo installed working platforms and used tie-offs to ensure safety of our crew.
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Jersey Turnpike Polyurethane Grouting
The Job
This Jersey Turnpike polyurethane grouting project is located next to Secaucus Junction in North Jersey. It is part of a larger paving and rehabilitation project. The work location is the exit departure slabs for the 15X tollbooth over Penhorn Creek.
The Challenge
The departure slab (closest to the toll booth) for this structure settled about six inches. The adjacent barrier walls are integrated into an MSE wall, which has an open graded stone reinforced zone. The cause of the settlement is due to consolidation of underlying soft soils, which are prevalent in the area.
Before CJGeo’s involvement in the project, the design engineer consulted with a chemical grout manufacturer representative. This person designed a grouting program to address voids below the pavement and within the underlying soils, up to eight feet below grade.
The Solution
The general contractor awarded the polyurethane grouting work to CJGeo due to our extensive experience performing geotechnical polyurethane grouting on transportation projects.
CJGeo mobilized a single polyurethane grouting crew to execute the plan designed by the chemical grouting manufacturer representative. It took a single crew two onsite shifts to perform about 7200 pounds of polyurethane grouting. The material was equivalent to CJGrout 48NHL.
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T Wall Lightweight Backfill
The Job
This T wall lightweight backfill project is located in Boston, Massachusetts. The bridge is located on the Lowell Line, within the MBTA‘s Commuter Rail Maintenance Facility.
The Challenge
CJGeo has been involved in this alternative delivery project since 2020, helping to optimize the use of CJFill-Ultra Lightweight fill to facilitate constructing a new embankment over underlying compressible soils.
In this specific location on the project, curved T walls were installed along the curved alignment (different radius) of the existing embankment. A sheet pile SOE retains the existing embankment. Due to highly irregular spaces, limited access, lightweight aggregate, such as foamed glass, would be exceptionally difficult to install and ensure adequate compaction.
The Solution
CJGeo proposed 26lb/cuft CJFill-Ultra Lightweight as the optimal material for the T wall lightweight backfill. The lowest 4′ is CJFill-High Permeability. Because CJFill is a self consolidating fill, there’s no compaction required. This practically eliminates chances of backfill consolidation. On a curved, relatively high speed commuter rail alignment, settlement could be quite risky if it were to occur.
For the first phase, CJGeo mobilized a single dry batch cellular grout plant. The work took a total of five days.
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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 and using preformed foam from Aerix Industries 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. The work took around two weeks, using the dry batch generation method.
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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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Sheet Pile Joint Sealing
The Job
This sheet pile joint sealing work is part of the Thimble Shoals parallel tunnel project. The project is located between Islands 1 and 2 of the Chesapeake Bay Bridge Tunnel. The Chesapeake Bay Bridge Tunnel crosses the opening of the Chesapeake Bay, connecting Norfolk/Virginia Beach and the Eastern Shore.
The Challenge
Water was leaking out of a joint in the precast splash wall adjacent to the TBM slurry separation pit. Any time it rained, precipitation landing in the slurry pit would flow out of gaps in the sheet pile wall. It then passed through the roughly 3′ of soil between the sheet pile wall and splash wall, and then out through joints in the splash wall.
The Solution
CJGeo proposed using a single component, hydrophilic chemical grout to seal the joints. Hydrophilic grout is best for this particularly repair because:
- the area is rather dynamic, so hydrophilic’s ability to flex and stretch without tearing helped to ensure longevity
- the area is constantly exposed to moisture, so dimensional stability is not a concern.
A CJGeo chemical grouting crew of three people completed the sheet pile joint sealing repairs in less than a day. Some chemical grout extruded out through the joint in the splash wall. It was broken off flush with the surface and disposed of offsite.
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MSE Wall Lightweight Backfill
The Job
This MSE wall lightweight backfill project is located near Richmond, Virginia. The geotechnical investigation for a double bridge replacement in Amelia County, Virginia found a layer of compressible soils below four proposed abutments.
Anticipated settlement exceeded allowable settlement, so the abutments were designed to be backfilled with expanded shale lightweight aggregate.
The two parallel bridges have an AAWDT of 14,000. They carry a rural divided highway (US-360) over Norfolk Southern Railway & Business 360 in Amelia Courthouse, Virginia.
The Challenge
Lightweight fill placement had to be unaffected by frequent rail traffic, have a limited footprint, and be economical. The anticipated settlement at design was 2.5 inches. A challenge arose during construction mobilization due to Covid-related issues. There was nowhere to stockpile the lightweight aggregate onsite. But the trucking market was so unreliable, that the material needed to be staged onsite. This was to ensure continuous MSE wall construction.
The Solution
CJGeo provided a value engineering proposal to utilize 30lb/cuft CJFill-Ultra Lightweight cellular concrete in place of the expanded shale lightweight aggregate. This significantly reduced the unit weight of the lightweight fill. Given the 70lb/cuft density used in the design, further reducing the anticipated settlement.
CJGeo mobilized a 200CY/hour low density controlled low strength material (LD-CLSM) plant to the site and placed lifts ranging in size from 35 to 300CY. Wall erection crews were able to walk on the in-place cellular concrete without leaving footprints as quickly as 4 hours after each placement.
The total project volume was approximately 7200CY.
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