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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Stone Arch Lightweight Backfill
The Job
This stone arch lightweight backfill project is located in Somerset, New Jersey. The stone arch bridge, constructed in the 1800s, was experiencing significant scour at the bases of the arch. This caused differential settlement of the structure, and deterioration of the wing walls.
The bridge is adjacent to a historic mill structure. Due to historic preservation requirements, the structure had to be maintained in kind, as opposed to replaced.
The bridge was originally bearing on shallow stone foundations.
The Challenge
As part of rehabilitating the structure, structural engineers designed two new mass footings in the stream bed to underpin the edges of the stone arch. Then, to strengthen the arch designed a 12″ thick reinforced concrete arch overlay on top of the stone arch for the full length/width of the bridge.
In order to compensate for this additional weight, designers determined that a lightweight fill material was needed to reduce the chances of inducing settlement.
Designers also evaluated remedial deep foundations but determined that lightweight fill was the fastest and most economical solution.
The Solution
After the structure had been rehabilitated, CJGeo installed 325CY of 30lb/cuft CJFill-Ultra Lightweight to complete the stone arch lightweight backfill installation. Placed in lifts up to 4 feet thick, the work was took just three days.
By using 30lb/cuft non-permeable cellular concrete, the dead load on the underlying soil decreased by up to 935lbs/sqft relative to compacted soil backfill.
Cellular concrete is self-consolidating and pumpable hundreds of feet. Therefore, single side access was not a problem, and no compaction equipment was necessary.
A crew of two workers completed the pour using continuous wet batch generation. CJGeo chose wet batch generation due to the relatively small daily volume of material placement.
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Coal Pier Sinkhole Grouting
The Job
This pier sinkhole grouting project by CJGeo is located at the mouth of the Elizabeth River, off the Chesapeake Bay. 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 trans-loading facilities in the world. As an around-the-clock facility built around precision logistics, there’s little tolerance for disruption or downtime.
The Challenge
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.
The Solution
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 hydro insensitive, 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.
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PA Turnpike Undersealing
The Job
This PA Turnpike undersealing project is located on the Northeast Extension of the Pennsylvania Turnpike. The Northeast Extension runs from Philadelphia to Scranton. 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 this work area, the turnpike has two northbound and two southbound lanes. A cast in place barrier wall separates the lanes. The pavement is an approximately nine inch thick rigid concrete with up to eight inches of asphalt overlay. Joint spacing ranges from twenty feet to eighty feet.
The Challenge
In order to keep MOT in place continuously, work had to be done 24 hours per day. Multiple mobilizations were used to work around bridge repairs at three different overpasses in the undersealing work area.
The Solution
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 hydro insensitive, 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 operations happened overnight. Grouting during the day is safest, and allows for easy visualization of the entire zone of influence. By working continuously, the general contractor was able to keep MOT in place continuously, avoiding the cost of setting and pulling MOT each day.
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Bridge Approach Polymer Grouting
The Job
This bridge approach polymer grouting project is located just outside of Washington, DC. The George Washington Memorial Parkway connects Washington, DC with Fairfax and Alexandria Counties in Virginia. Originally designed as a scenic route, the road has transformed into a heavily used commuter route in and out of Washington. The road runs along the Potomac River, with bridges crossing deep ravines, including Windy Run.
The Challenge
Our biggest challenge with this project was making sure this heavily populated commuter route was completed in a timely fashion.
The Solution
CJGeo proposed polyurethane compaction grouting using CJGrout 30NHL. CJGrout 30NHL’s design is for improving the bearing capacity of loose soils similarly to cementitious compaction grouting. Grouting is done on 4’ centers, at 5’, 10’ & 15’ below grade. Top-down grouting ensured maximum densification of underlying soils. This grouting program was generally prescriptive, but with ground movement of 0.5 inches cutoff criteria.
CJGeo installed approximately 25,000 pounds of CJGrout 30NHL to increase the bearing capacity of the embankment soils. Due to polyurethane grout’s nearly immediate cure, CJGeo helped ensure that ground improvement stayed out of the critical path of this accelerated project. Pre & post grouting DCP testing showed improvement in soil density.
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