Atlanta cellular concrete
The Job
This Atlanta cellular concrete installation is part of Atlanta Watershed Management’s Niles Avenue Sewer Improvements project. The project took approximately 2500LF of microtunneling to install a new 18″ sewer main.
The Challenge
A 72″ microtunnel was chosen, which required approximately 1200CY of annular space grouting. Operations were challenged by the pandemic hitting in the middle of the project.
The Solution
CJGeo proposed 30lb/cuft CJFill-UL cellular grout for the annular space grout. This allowed the contractor to avoid mechanical buoyancy control during grouting operations during single lift grouting. Buoyancy control of the carrier was one of the driving factors for using CJFill-Ultra Lightweight for this Atlanta cellular concrete project. Because the tunnels had a good amount of slope on them, grouting in multiple stages would have been impractical. Flowable fill would have floated the carrier pipe, even if it was full of water.
Over two mobilizations, CJGeo generated the cellular concrete grout onsite using preformed foam from Aerix Industries and placed it via shafts which were up to 40 feet deep. CJGeo chose wet batch generation due to the project volumes.
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Industrial Basement Abandonment
The Job
This industrial basement abandonment project is located in Southside, Virginia. As part of an adaptive reuse project of an abandoned industrial site, the former onsite power plant’s stacks were being rehabilitated. Multiple tunnels and basement rooms had to be completely filled.
The Challenge
Due to safety concerns, nobody could enter the basement. No as-builts were available. Camera inspection through holes cored in the ceiling showed significant numbers of passageways and obstructions. The fill material had to be:
- exceptionally mobile,
- placed in deep lifts,
- and as light as possible.
Fill density was a concern because the basement was up to 15′ deep. 150lb/cuft traditional flowable fill would have caused too much anticipated settlement. Settlement of the basement structure could potentially cause settlement or movement of the adjacent smoke stacks.
The Solution
CJGeo proposed 25lb/cuft cellular concrete for the lightweight fill material. Using onsite colloidal batching, CJGeo can place material up to 20′ deep in a single lift, without consolidation. Because CJFill-Ultra Lightweight is so lightweight, the entire 15′ deep basement fill dead load was the same as from just 2′ of traditional flowable fill. For this application, Aerlite-iX was the most appropriate cellular concrete foaming agent.
CJGeo mobilized a 150CY/hour dry batch plant to the site after staging 300 tons of cement onsite using our in-house cement pig & trucking operation. Over four days onsite, CJGeo place 2700CY of CJFill-Ultra Lightweight material to complete the industrial basement abandonment.
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66″ Water Main Abandonment
The Job
This 66″ water main abandonment is part of the The Purple Line’s construction. The Purple Line is a light rail line project in suburban Maryland. It will increase connectivity within Maryland’s suburbs of Washington, DC. The project involves extensive utility relocation to facilitate installation of large embankments and the extensive infrastructure required for a double track rail corridor dropped into the middle of an already exceptionally congested/dense corridor.
The Challenge
As part of the project, a large MSE wall was built over approximately 3000LF of 66″ PCCP water main. To avoid any future maintenance problems under the rail alignment, a new line was put in adjacent to the embankment. The old line had to be completely full of grout.
Due to construction sequencing, the embankment installation happened before the water line relocation.
The Solution
CJGeo worked with the utility relocation contractor to design a grout mix and grouting program that provided sufficient bearing capacity to eliminate concerns about future stability. The ultimate design for the mix was a 100psi CJFill-Ultra Lightweight cellular grout. Because the embankment was already in place, the entire 3000LF stretch was accessible from just two access points.
CJGeo used a 200CY/hour dry mix batch plant onsite to generate and pump the cellular concrete up to 1500LF to place the material. This 66″ water main abandonment took four days to complete, and didn’t disrupt any of the adjacent construction activities.
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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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Lightweight Plaza Fill
The Job
Lightweight plaza fill for a private age restricted high rise new build in Tysons Corner, Virginia. Tysons Corner was historically an office heavy area of Fairfax County, but this project, along with many others, is increasing the amount of residential real estate in the area.
The Challenge
To manage dead loads over the four story parking deck, while achieving a landscape design requiring up to five feet of fill, the designer specified 20lb/cuft CJFill-High Permeability cellular concrete for the plaza fill material. The material had to be permeable, and placed up to 600′ from the closest access point for a plant. The deck elevation is about 30′ above the laydown area.
The total square footage of placement needed to be around 17,000 square feet. EPS foam blocks were an alternative fill material. However, EPS would have been exceptionally time consuming and expensive to install.
The Solution
CJGeo mobilized a 200CY/hour dry batch plant and crew, who generated up to 500CY/day for placement via hoses and a boom pump to successfully fill the plaza areas. Total project volume for this lightweight plaza fill was approximately 2200CY.
All material is onsite from dry bulk cement, with zero exposure to the hit or miss ready mix concrete market. An onsite cement storage pig allows overnight raw material delivery and staging, to eliminate traffic disruption.
The 20lb/cuft CJFill-High Permeability Low Density Controlled Low Strength Material placement was formed by the site concrete contractor. After the CJFill-HP had set, the site concrete contractor poured exposed aggregate sidewalks directly on top of the CJFill-HP. Other areas of the deck were backfilled with engineered lightweight soil, and then planted with extensive landscaping.
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Hollow Abutment Filling
The Job
This hollow abutment filling project is located in Buckland, Massachusetts. Buckland is a small town on the east end of the Berkshires. The bridge conveys a rural highway over a drinking water impoundment. As part of a bridge rehabilitation for MassDOT, two hollow abutments were specified for filling. This would turn the structural approach/departure slabs into slab on grade. The alternative would have been to completely replace the structures. Filling them with traditional weight backfill would have caused significant settlement.
The Challenge
It was up to 30′ from the bottom of slab to the underlying soil which had originally been installed to backfill the abutments. The lightest possible material capable of providing sufficient support to the pavement was required. This would reduce the loads applied to the bridge from the backfill. Due to the very constrained access (a few cored holes through the deck, and a few square foot port cut into each abutment face), the lightweight material had to be self-consolidating (placed as a fluid).
Due to integrated beams for the structural slabs, there were 12 different individual pockets which were up to 2′ tall. Each had to be vent independently during the final lift. Four of were under live traffic because the road had to have one lane open at all times.
The Solution
CJGeo worked with the general contractor to formulate a plan to vent the individual pockets from outside of the open lanes. This helps to ensure a complete fill without requiring a complete road closure. Over the course of two mobilizations, CJGeo placed 2,840CY of 25lb/cuft CJFill-Ultra Lightweight to fill the abutments.
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8″ Pipe Abandonment
The Job
This 8″ pipe abandonment project is located outside of Washington, DC. As part of continuing waterline replacements, a utility contractor in Fort Washington, Maryland, needed to abandon 10,600LF of 8″ water main. The utility and DOT both require grouting of all utilities 6″ and larger taken out of service.
The Challenge
In order to minimize the number of placement points, the grout needed to be exceptionally mobile.
The Solution
CJGeo proposed a 30lb/cuft CJFill-Ultra Lightweight (CJFill-UL) cellular grout, and worked with the client to design a grouting plan that would allow grouting all 10,600LF of pipe from just three access points. CJGeo performed the grouting over a period of two days, with no additional excavation required from the customer other than their original tie ins/disconnects.
By cutting the pipe at three locations, it was split into roughly equal segments. Each of around two thousand six hundred feet. 30lb/cuft CJFill-Ultra Lightweight is easily pumpable this distance without yield loss.
To do this same work with flowable fill would have required approximately thirty five access points. This would be to split the pipe into roughly thirty six segments around three hundred feet, each. Even then, pumping flowable fill three hundred feet through eight inch pipe is very difficult. By using CJFill-Ultra Lightweight for this pipe abandonment project, the general contractor saved about two weeks off of their schedule, and tens of thousands of dollars.
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Union County Annular Space Grouting
The Job
This Union County annular space grouting project is located in North Carolina, near Charlotte. Due to a rapidly increasing population, Union County, North Carolina installed a new raw water intake. It required a nearly 11 mile long raw water line to supply a water treatment plant.
The Challenge
There are dozens of road crossings along the alignment. 17 crossings are jack & bore, and require annular space grouting per NCDOT requirements. Given the length of the project, there weren’t any ready mix providers who could cover this entire annular space grouting in North Carolina project.
The Solution
CJGeo has multiple NCDOT approved mix designs, for CJFill-UL. CJGeo sourced material from two different ready mix providers. Each annular space on all crossings was grouted per NCDOT requirements. CJGeo has approved mix designs with the North Carolina Department of Transportation that cover the entire state. From the Outer Banks to Asheville, Raleigh/Durham, Wilmington & Charlotte, CJGeo has you covered.
The density for this work was 30lb/cuft CJFill-Ultra Lightweight. 30lb/cuft CJFill-Ultra Lightweight breaks above NCDOT’s minimum 125psi at 28 day unconfined compressive strength requirement for annular space grout. Because the project volume on this job is relatively low per crossing, CJGeo used ready mix for the raw slurry. Ready mix typically isn’t best for large placements. But for small, spread out placements like this project, is a great fit.
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24″ Water Main Abandonment
The Job
This 24″ water main abandonment project is located in Fairfax, Virginia. Fairfax County is part of the rapidly expanding Northern Virginia region. As part of a large transportation project, 2000 linear feet of 24″ water main were being relocated out of a highway right-of-way.
The Challenge
Due to phasing, the old water main was located under the existing roadway and could not be accessed, except for at one point near the center of the run. So, the abandonment grout had to meet VDOT’s minimum strength requirements for flowable fill, and be pumpable up to 1100LF at low pressure. VDOT’s minimum 28 day unconfined compressive strength requirement is 30psi.
The Solution
CJGeo grouted each run of pipe using 30lb/cuft CJFill-Ultra Lightweight low density controlled low strength material. Each CJFill-UL placement took fewer than two hours, and required no additional traffic control, disruptions to other construction activities, or help from the utility contractor after they installed the bulkheads.
The 28 day compressive strength of 30lb/cuft CJFill-Ultra Lightweight cellular grout is 150psi. This significantly exceeds VDOT’s minimum compressive strength for controlled low strength material (flowable fill).
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Facing a similar challenge to this 24″ water main abandonment project that CJGeo completed using CJFill-Ultra Lightweight cellular concrete? 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.
Grain Silo Tunnel Backfilling
The Job
This grain silo tunnel backfilling project is located in Tampa, Florida. As part of a redevelopment project in downtown Tampa, Florida, a large grain milling facility was moving operations from the downtown port to a new facility further down Tampa Bay.
The Challenge
The facility is immediately adjacent to Tampa Bay. To minimize flood risks, the the entire structure is above grade. This includes the 8′ tall unloading conveyor tunnels. The structure was bears on a mat slab cast over thousands of auger cast piles. The unloading tunnels were only about 10% of each silos footprint. So, the areas long side of the tunnels needed to be filled.
Due to the slipform construction, there was very limited access. So the backfill material around the tunnels needed to be pumpable. Flowable fill was an option, but is very heavy. The design build contractor identified cellular concrete as a potential backfill material. This could save nearly 1ksf of dead load off of the mat foundation.
The Solution
CJGeo worked with the design builder to create a mix design that would minimize the amount of dead load on the foundation, while providing adequate support for the bin floor when fully loaded with grain. Over the course of a few weeks, CJGeo crews placed nearly 7200CY of 25lb/cuft CJFill-Ultra Lightweight cellular concrete. Rodbusters were able to start setting steel the day after completion of the final lift in each of the silos.
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Facing a similar challenge to this grain silo tunnel backfilling load reducing fill project by CJGeo? 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.
