Secaucus Lightweight Fill
The Job
This Secaucus lightweight fill project is located just across the Hudson River from Manhattan. It’s part of a completely gut of an existing 100,000 square foot distribution and logistics building. While the ground in Secaucus is terrible, the real estate is valuable because of its close proximity to New York City, and also at the core of the dense, urban North Jersey market.
The Challenge
Since original construction in the 1970s, the floor of the building has settled nearly two feet. This is due to underlying compressible, organic soils. As the underlying soils consolidated, and the floor settled, two subsequent floors were poured on top of the existing floor. Varying thicknesses of recycled concrete and other base materials were used to level over the differentially settled previous floors in preparation for the new floor pours.
The goal of the full gut was to build a food grade space. This is to bring the building into a more profitable sector. To do this, minimizing the amount of future settlement was important. Reports from multiple consulting geotechs in the past recommended undercutting and lightweight fill placement as a viable option for achieving this goal. The CMAR reached out to CJGeo about designing and implementing an undercut and lightweight fill program. This was based on our experience on similar projects in the Secaucus area.
The Solution
CJGeo’s inhouse geotechnical engineer worked with the CMAR’s geotechnical consultant. We used RocScience’s Settle 3 program to design an undercut program that would bring anticipated settlement to no more than 1.5 inches. Given the global subsidence of the area, along with rising ground water levels and increasing flood chances, buoyancy was also a design consideration. The total system (floor, base stone & lightweight fill) had to have a minimum 1.1 factor of safety against uplift in fully inundated condition. As an added measure of safety, given the very large footprint of the fill, limited permeability soils immediately below the lightweight fill, and disruptions associated with any buoyancy, CJGeo recommended not factoring infiltration into reduced buoyancy.
The final design includes a 42 inch undercut, followed by placement of 32 inches of CJFill-Ultra Lightweight foamed concrete fill. CJGeo mobilized a single dry batch plant to the site, and placed approximately 8,500 cubic yards of CJFill-Ultra Lightweight material. Production was as high as 1100 cubic yards per day.
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Wet Well Lightweight Fill
The Job
This wet well lightweight fill project is located at HRSD’s Nansemond Treatment Plant, in Suffolk, Virginia. As part of an extensive capital improvement project, the Nansemond Treatment Plant is being upgraded to accept increased flows. The additional flow will be coming via the Hampton Roads Sanitation District’s Hampton Roads Crossing (HRX) project.
As part of the upgrades, a large wet well requires abandonment filling. The structure bears on deep foundation piles, and underlying soils are extremely poor. Therefore, the structure requires low density, self-consolidating fill instead of traditional flowable fill.
The Challenge
The Construction Manager At Risk evaluated multiple lightweight fill materials. Geofoam would provide the least additional load, but due to safety concerns from access into the structure, would not be practical. Foamed glass aggregate fell below maximum allowable densities, but would be difficult to place and compact in the tight space. Expanded shale would be too heavy, and very difficult to place and compact.
The Solution
CJGeo worked with the CMAR, along with the geotechnical and structural engineers to design a fill program which would minimize density, maximize safety, and be optimal for cost and schedule.
CJGeo mobilized a 200cy/hour cellular grout plant to the site, and placed 430 cubic yards of 25lb/cuft CJFill-Ultra Lightweight foamed concrete fill. To manage lateral loads on the walls during placement, two ten foot deep lifts brought the fill to finish elevation.
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NYC Cellular Concrete
The Job
This NYC cellular concrete project is located at the William McCray Playground in Manhattan. The existing playground had experienced significant subsidence, which damaged the already outdated equipment.
The entire playground was demolished, in order to install a new updated facility, including play equipment, basketball court and spray equipment.
The Challenge
Design documents called for three feet of 25lb/cuft lightweight fill material over roughly 4,000 square feet of the site. Two options were given to contractors; 25lb/cuft cellular concrete or foamed glass aggregate.
Logistics for any work in Manhattan are tricky. Challenges include truck traffic limitations, constraints on work time and noise, and the narrow, congested streets. There was no room on the site for any stockpiles.
The Solution
The customer determined using 25lb/cuft CJFill-Ultra Lightweight fill by CJGeo would be the lowest risk, most economical, and fastest method allowable by specification. Because the equipment for generating foamed concrete fill is mobile and compact, the tight site wasn’t a problem.
CJGeo brought in just four loads of cement in order to generate the approximately 550 cubic yards of foamed concrete material. Cold temperatures didn’t affect the operation; it froze the night between the two pours, and also the night afterwards. No tenting or protection is required.
The day following the second pour, the customer was able to start placing pavement base on top of the cellular concrete.
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Lightweight Fill Over Waterline
The Job
This lightweight fill over waterline project is located north of Baltimore, Maryland, in Edgewood. It is part of a modernization and widening of I-95. This includes replacement of multiple bridges crossing I-95, including Clayton Road. Clayton Road is a rural, two lane roadway. However, I-95 in this area is a very heavily traveled, critical piece of the east coast megalopolis infrastructure.
About half of the City of Baltimore’s raw water supply parallels I-95 in this area. It runs through a 108″ PCCP raw water main that originates at the Susquehanna River, a few miles north of the project site.
The Challenge
As part of replacing the Clayton Road bridge over I-95, the bridge clearance was increased. To facilitate this, the approach/departure embankments had to come up a few feet. On the west end, this was not a problem; there are no underlying utilities or compressible soils.
On the east end of the bridge, however, the 108″ PCCP raw water main passes under the roadway embankment, in an area where grades needed to come up by an average of three feet. The pipe cannot see any additional load.
The Solution
Two potential solutions for this challenge are using lightweight fill to balance loads, or install a pile-supported load transfer slab bridging over the pipe. Lightweight fill was the fastest and most economical option.
CJGeo mobilized a single dry batch plant to the site. Over the course of six days onsite CJGeo poured 2,000 cubic yards of CJFill-Ultra Lightweight load reducing fill. The fill mass is roughly 10 feet thick at the deepest. At 25lb/cuft, this balances the loads within the zone of influence of the pipe. The pipe sees no increase in loads despite up to 4 feet of additional elevation over it.
Due to CJGeo’s exclusive use of high shear mixing, the contractor was able to place aggregate base on top of the CJFill-UL the following day.
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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 to place the foamed concrete.
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Hobas Pipe Backfilling
The Job
This Hobas pipe backfilling project is located in Baltimore, Maryland. It is one of the last steps in an emergency storm drain collapse project.
The Challenge
The original design for this project was to slip line a roughly 100 linear foot length of 108″ brick sewer that had collapsed. There was a massive void above the pipe, which was going to be filled with CJFill-Ultra Lightweight after the new pipe was slid in. However, the soil collapsed and the repair turned into an open cut repair.
The pipe is more than 100 years old, and was installed in a rock trench, the walls of which were uneven and unstable. Extensive rock bolting and stabilization was installed to facilitate the installation of the pipe. In order to ensure uniform bedding and stability of the new pipe, Hobas and the EOR recommended backfilling the pipe to at least 1′ above the crown with self-consolidating fill.
150lb/cuft flowable fill would have resulted in tremendous uplift forces on the pipe, unless installed in impracticably thin layers.
The Solution
CJGeo proposed cellular grout as an alternative, in order to reduce the uplift while decreasing the number of lifts.
Due to water infiltration near the invert, the first lift was done using 65lb/cuft CJFill-Under Water. Once the first lift was in place, the placement was switched to CJFill-Standard.
All material was generated onsite from bulk cement using CJGeo’s colloidal dry batch generation process.
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USACE Pipe Abandonment
The Job
This USACE pipe abandonment project is located in Muncie, Indiana. The project was part of a locally-administered stormwater improvement project. Because the pipes pass through a US Army Corps of Engineers levee, abandonment of the existing culverts had to be performed to USACE specifications.
The Challenge
New pipes and an endwall wall had been in place for a few months. All paving restoration was done, and the original pipe discharged through the new endwall. Specifications for USACE pipe abandonment call for cellular grout with a minimum of 300psi unconfined compressive strength at 28 days, 100psi penetration resistance at 24 hours, and minimum wet cast density of 45lb/cuft (CJFill-Standard).
The Solution
The contractor reached out to CJGeo due our expertise in cellular concrete placements with tight specs and discerning owners.
CJGeo mobilized a wet batch cellular grout crew to the site, and filled the two pipes in about an hour. Aerix Industries supplied the Aerlite-iX preformed foaming agent. Wet batch method was best due to the relatively low volume of the placement. Both runs of pipe are 36″ CMP. The first run is 73 feet, the second run 103 linear feet, for a total of 47 cubic yards.
CJGeo successfully filled the two runs of pipe. Confirmation of fill was venting of uniform grout out of the 6 & 12 o’clock ports on each end of both runs.
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NCDOT abandonment grouting
The Job
This NCDOT abandonment grouting project is located outside of Chapel Hill, North Carolina. The abandonment grouting is the final step in a gravity main replacement project. The scope requires filling 3,023 linear feet of 24″ RCP gravity sewer with NCDOT-approved flowable fill.
The Challenge
This gravity main runs entirely in a cross-country backwoods right of way. Along the alignment, there are a few road crossings, which require the NCDOT approved material.
Because the new pipe is in the same right of way, there are multiple locations where new and old pipe alignments cross. This breaks it into a collection of smaller runs, as opposed to one continuous run of pipe.
The Solution
If this was one continuous run of pipe, it would be a great candidate for dry batch generation cellular grouting. The 352CY project volume would only take about two hours to fill.
However, being broken into multiple, shorter runs in the middle of the woods, meant that wet batch equipment was more appropriate from an access and productivity perspective.
CJGeo mobilized a wet batch crew to the site, and it took them two days to complete the work. There were a total of 11 runs of pipe and six placement points. The longest run was 1113 linear feet, the shortest only 56.
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NCDOT pipe abandonment
The Job
This NCDOT pipe abandonment project is located outside of Wilmington, North Carolina. It is part of a large highway improvement project to improve capacity in the rapidly expanding southern coastal North Carolina area.
The Challenge
NCDOT requires grout fill for most abandoned pipes within their right-of-way. Traditionally this is done using flowable fill mixes. Using flowable fill for short abandonment is generally pretty simple.
However, this project has more than 100,000 linear feet of pipe ranging from 6″ to 36″ to fill. Most flowable fill mixes won’t go more than a couple hundred feet in best cast conditions. The utility contractor was looking at having to dig up to five hundred access points to place flowable fill. That’s incredibly time consuming and costly.
The Solution
The utility contractor reached out to CJGeo about performing the abandonment grouting on this project, using low density cementitious material (cellular concrete).
Due to the highly variable pipe diameters and run lengths, CJGeo proposed a mix of wet batch and dry batch cellular concrete generation.
Wet batch was used for the lower volume runs. Dry batch is best suited for large volume runs. Over the course of a few months, CJGeo mobilized multiple times to fill runs as long as a mile at a time.
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Ohio Annular Space Grouting
The Job
This Ohio annular space grouting project is located in Akron. It is part of the Northside Interceptor, being constructed by Granite Construction. The total project budget is about $215 million, to construct 6,660 linear feet of 16.5′ diameter segmental liner tunnel.
While the main tunnel is single pass, there are multiple tie-ins to the structure. Some tie-ins are open cut, and another is a microtunnel. The microtunnel is 530 linear feet of 48″ pipe.
The Challenge
Plans call to grout the annulus between the carrier pipe and microtunnel casing with 600psi at 28 day material. A lean concrete mix to achieve this compressive strength would be significantly heavier than water. This can cause significant headaches managing carrier pipe buoyancy, as the heavier the grout, the greater the uplift during grouting.
The Solution
CJGeo proposed a 55lb/cuft CJFill-Standard mix to meet the compressive strength requirement, while minimizing carrier pipe buoyancy. Because the proposed material is less dense than water, filling the carrier pipe with water during the grouting process keeps the carrier pipe in place.
A CJGeo dry batch cellular grout crew placed 119 cubic yards of 55lb/cuft CJFill-Standard over two hours to fill the annular space in a single lift. Cellular concrete is also referred to as foamed concrete fill.
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