I-64 Soundwall Backfill
The Job
VDOT’s I-64 widening project is a multi-phase widening of Interstate 64 between Richmond & Newport News. This soundwall backfill work occurred as part of Segment 2, near the Queen’s Creek bridge.
The Challenge
Approximately 150LF of a combination sound & retaining wall needed to retain more than 10′ of backfill. In order to keep the drilled foundation size consistent along the alignment, the backfill material needed to be significantly lighter than the soil backfill used in other segments, where there was minimal retained depth.
The material needed to be freely-draining and less than 40lb/cuft. To ensure proper drainage, the lightweight fill material couldn’t impact the function of the combination drain waterproofing system applied to the wall.
The Solution
CJGeo proposed backfilling the affected wall segments with 30lb/cuft CJFill-UL. Used extensively by VDOT for backfilling the retained zones of MSE walls, CJFill-UL provides significantly better bearing capacity than soils or aggregates, and once cured does not apply lateral loads to the structures it is placed against.
During installation, lateral pressure from the cellular concrete is simply the hydraulic head. Hydraulic head is calculated by multiplying the pour thickness, in this case 5′, by the wet cast density, here 30lb/cuft, so 150PSF. Because CJFill-Ultra Lightweight cellular concrete does not contain any aggregate, there is no internal friction to contribute towards lowering pressures.
CJGeo placed approximately 200CY of CJFill-UL for the soundwall backfill the wall in two pours, each approximately 5′ thick. The contractor was able to place the pavement base on top of the material the following day.
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Veranda St Bridge Infill
The Job
This bridge infill work was part of Maine DOT’s Veranda Street Bridge Replacement Project, in Portland, Maine. Using rapid bridge replacement, the project took a three span bridge and converted it to a single span bridge.
The Challenge
To manage settlement due to up to 80′ of underlying WOH material, lightweight fill was needed to infill two spans, and backfill the new abutments. The absolute lowest unit weight possible requirement led to a hybrid cellular concrete/EPS fill design. The bulk of the infill is EPS blocks. However, due to the irregular surfaces, piers, etc., and the need for a lightweight load distribution slab, cellular concrete was integral to the design.
The Solution
Over two mobilizations for the bridge infill, through snow and freezing temperatures, CJGeo placed 3200CY of 25lb/cuft CJFill-Ultra Lightweight cellular concrete for abutment backfilling and existing pier infills. Then, CJGeo placed 778CY of 30lb/cuft CJFill-Ultra Lighweight as a topping slab over the EPS fill masses.
To ensure high quality material and minimize weather-related risks, CJGeo used onsite batching to generate the material. A mobile batch plant custom built for generating cellular concrete mixes water and dry bulk cement onsite. The cement paste and foam blend continuously to generate a completely homogenous material. With a slump of around 11.5 inches, both densities of CJFill-Ultra Lightweight cellular concrete were able to flow around all of the existing structures and provide a void-free fill.
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New Jersey Grade Crossing Stabilization
The Job
This grade crossing stabilization project is located in Edison, New Jersey. A precast modular grade crossing (Oldcastle StarTrack) crossing developed significant pavement deterioration. NJDOT directed the railroad to stabilize and lift the panels and then patch the adjacent asphalt.
The Challenge
The grade crossing sees up to 8 trains per day (heavy industrial service), and crosses a four lane arterial highway. So, there wasn’t any allowable downtime. Because of this, traditional cementitious grout was not a viable option. Cementitious grouts generally need hours to reach strength, so can significantly disrupt train schedules, and require long lane closures for vehicles.
The Solution
CJGeo proposed grouting the panels using CJGrout 60NHL. 60NHL is a geotechnical polyurethane grout specifically formulated for heavy applications such as rail and aircraft loads. A CJGeo polyurethane grouting crew mobilized to the site and in fewer than 2 hours onsite restored the affected panels. Another name for this process is concrete raising.
This grade crossing stabilization project did not require ground improvement grouting. The cause of the settlement was the bedding fines washing out, so only shallow grouting was necessary.
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Garden State Parkway grouting
The Job
This Garden State Parkway grouting project is located near Middletown, New Jersey. As part of ongoing large diameter culvert rehabilitations and replacements, four new bored stormwater crossings and the original culvert they replaced needed to be grouted. The tunnels ranged from 120″ down to 74″, for a total of 312CY, and the abandonment required 405CY.
The Challenge
Grout needed to meet the minimum strength requirements of the owner, and ideally needed to be light enough to facilitate single lift annular space grouting.
The Solution
CJGeo’s preconstruction team worked with the general contractor to design a grouting program which facilitated single lift abandonment of the original culvert, and single lift grouting of the four various annular space runs. CJGeo utilized onsite dry batching to generate 30lb/cuft CJFill Ultra Lightweight cellular concrete.
CJFill is a type of Low Density Controlled Low Strength Material, or LD-CLSM. The “low density” comes from using preformed foam, in this case Aerlite-iX, as a substitute for aggregate. This significantly reduces the unit weight, which exponentially increases pumpability. In this case, all 405 cubic yards of abandonment grout were placeable at once.
Because CJFill LD-CLSM is significantly lighter than water, each annular space grouting run was doable in a single lift. Filling each carrier pipe partially with water was all it took to facilitate this.
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CBBT Sheet Pile Pregrouting
The Job
This sheet pile pregrouting project is located in the Chesapeake Bay. The Chesapeake Bay Bridge Tunnel’s Parallel Thimble Shoal Tunnel Project is constructing a second tunnel parallel to the original to reduce traffic congestion. All launch & receiving work is on man-made islands in the Chesapeake Bay. The islands are dense with utilities, equipment and operations facilities associated with the existing tunnel, which is in continuous use.
The Challenge
During previous phases, installation of sheet piling for tunneling activities and other driven elements induced consolidation of the loose sandy fill on the islands. This was causing settlement of duct banks, pavements and other structures, which were remedied by CJGeo using polyurethane compaction grouting.
In this case, sheet piles had to be driven immediately adjacent to the roadway. This is in order to excavate the receiving pit for the tunnel boring machine. The construction team was concerned about inducing settlement of the adjacent roadway. They reached out to CJGeo about performing compaction grouting under the footing for the original tunnel’s portal wall. This was after the wall had been demolished down to grade.
The Solution
CJGeo performed compaction grouting utilizing an NSF-certified potable water contact plural component CJGrout 35NHV polyurethane grout. Cutoff criteria was 0.10 inches of movement of the foundation or adjacent roadway. Upon completion of the compaction grouting by CJGeo, sheet piling installation started. There was only nominal movement of the foundation and roadway.
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North Carolina Tub Crossing Repairs
The Job
This tub crossing repairs project is located in Charlotte, North Carolina. Fifty two OldCastle StarTrack panels at four different grade crossings settled to the point of requiring slow orders at the crossings. In order to restore the track to normal speeds, the settlement had to be corrected.
The Challenge
Due to scheduling constraints with rail traffic, with very short windows on weekend nights, the owner elected to have the repairs completed during a single weekend shutdown period. While this allowed for longer work periods, it also meant that four crossings needed to be repaired in fewer than 24 hours.
The Solution
CJGeo mobilized two polyurethane grouting crews to the system, and grouted two crossings each during two shifts. All 52 of the panels were stabilized and lifted back to grade using CJGrout 48NHL, which allows for immediate resumption of rail traffic, from light rail to heavy haul.
Polyurethane grouting is also sometimes called structural polymer grouting. Regardless of name, the process works very well where fast return to service is important. In the case of tub crossing repairs, grout must set very quickly in order for rail traffic to resume. CJGrout 48NHL achieves 95% of its ultimate strength in fewer than 15 minutes.
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Spillway Bridge Grouting
The Job
This spillway bridge grouting project is located in Toano, Virginia. Toano is between Williamsburg and Richmond. Two DOT-maintained bridges crossing two privately owned dam spillways had to be closed because of extensive undermining of the spillways.
The undermining was allowing nearly all of the flow to happen below the spillway slabs. This caused large sinkholes to form adjacent to and under the roadway pavement. It also led to some settlement of the spillway slabs.
The Challenge
There was very little room to work–just under 4′ of clearance below the bridge beams. Also, the velocity of the water through the voids below the structure was quite high.
The Solution
CJGeo proposed a combination of plural component polyurethane grouting to address the water flows and voids, and hydrophobic chemical grout placed directly into cracks. A single CJGeo grouting crew was able to complete the repairs in a day (roughly 2500sqft of work, and approximately 4500lbs of CJGrout 35NHV61 polyurethane, plus 30 gallons of hydrophobic chemical grout). Dye testing during and after the grouting work confirmed that no more leaks were present under or around the spillway structures.
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9.5kCY MSE wall backfill
The Job
This MSE wall backfill project is located on Interstate 95 north of Baltimore, Maryland. The Express Toll Lanes will add extra capacity up the center of the existing roadway. This project is adjacent to a previous CJGeo project, where we placed 2,000 CY of CJFill-Ultra Lightweight cellular concrete as part of the Clayton Road Overpass reconstruction.
The Challenge
A 96″ diameter PCCP raw water supply line runs parallel to Interstate 95 along most of the project length. Originally, there was quite a bit of room between the roadway and the water line. However, as lanes are added, it’s gotten closer and closer to the PCCP water line. As part of this project, there are extensive ramp and embankment sections. They are immediately adjacent to the waterline, which is not in a condition to see any increase in loading.
To address this, designers specified lightweight material for the MSE wall backfill material.
The CJFill MSE Wall Backfill Solution
Originally designed for backfilling with Lightweight Expanded Shale Aggregate (LESA). CJGeo worked with the contractor to develop a hybrid MSE wall backfill material of 30lb/cuft cellular concrete and traditional weight 57 stone.
The relative depths of the two materials was selected so that the average density of the mass was equal to that of an entirely LESA backfill. This resulted in only needing roughly 2/3 the volume of lightweight backfill material.
Lightweight backfill is rarely less expensive as soil or traditional aggregates. However, by leveraging the very low unit weight of cellular concrete, a blended solution was possible that saved significant amounts of money.
CJGeo generated as much 500CY per day of CJFill-Ultra Lightweight to backfill the wall. The 30lb/cuft wet cast density provides adequate pull out resistance, and 140psi of unconfined compressive strength at 28 days.
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Bridge Approach Ground Improvement
The Job
This bridge approach ground improvement project by CJGeo is located in Richmond, Virginia. With multiple S curves and merges, I-195 in Richmond, Virginia is one of the most accident prone sections of interstate in Central Virginia. Significant settlement of multiple approach and departure slabs at various bridges didn’t make things any better. Improving the ride quality by addressing up to 6 inches of settlement was a critical part of a 2022 safety improvement plan.
The Challenge
Extensive settlement over the years had caused the pavement to become distressed. This was addressed over time with extensive patching of the pavement slabs. With no reasonable detour routes, shutting down traffic to facilitate repairs was not an option.
The Solution
While the original project designed required lifting all of the settled pavement, this would have been nearly impossible, given the extensive patching (including full depth filling of expansion joints with repair mortar).
CJGeo worked with the general contractor and VDOT to revise the repair plan to a combination of compaction grouting of the underlying soils, coupled with an asphalt overlay of the approach and departure slabs to restore the ride.
Polyurethane compaction grouting was performed to a depth of up to 25′ below the pavement surface. This was to consolidate poorly controlled backfill material, at two approaches (9 lanes total) and three departures (9 lanes total). Cutoff criteria was 0.05 inches of lift at each point/stage.
Milling and paving for a 30′ taper to provides a smooth transition and ride.
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30k CY Lightweight Embankment
The Job
As part of the redevelopment of the Sparrows Point industrial area of Baltimore, three bridges were to be replaced. The owner specified lightweight embankment techniques due to extensive compressible soils. Sparrows Point is undergoing a transition from a brownfield site to a buzzing logistics hub. Multiple new distribution centers, berths and manufacturing facilities have driven an explosion in vehicle volume.
The Challenge
The original embankments are industrial byproducts over underlying compressible soils. As part of the reconstruction, the embankments needed to be widened and raised up to six feet to increase clearance below the bridges for both highway and rail traffic.
Due to the underlying compressible soils, there were concerns that the approximately 30,000 cubic yards of fill material needed would cause settlement.
Most material was immediately behind the new abutments, and helped to optimize the deep foundations by reducing axial & lateral loads.
The compressive strength for the material was 80psi, with a target density of 25lb/cuft.
The Solution
CJGeo proposed 25lb/cuft cellular concrete as a lightweight fill material buildable with locally-sourced materials to reduce transportation related risks and exposure to trucking shortages. Cellular concrete was several hundred thousand dollars less expensive than either Lightweight Expanded Shale Aggregate or Foamed Glass Aggregate. It also doesn’t require onsite stockpiling, and freed up the general contractor’s labor force to perform work other than placing aggregate.
CJGeo poured the lightweight embankment structures using 25lb/cuft CJFill-Ultra Lightweight cellular concrete over four mobilizations. Because CJFill-UL is so lightweight, all forming was silt fence. Silt fence facilitates complex curves, and is very economical. Side slopes were poured at 2′ vertical steps on 4′ horizontal insets.
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