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Cellular Concrete Projects

By applying unique solutions to increase the safety and longevity of our environment.

66″ Water Main Abandonment

The Job

The Purple Line is a light rail line project in suburban Maryland designed to 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 needed to be installed over approximately 3000LF of 66″ PCCP water main. In order to avoid any future maintenance problems under the rail alignment, a new line was installed adjacent to the embankment, and the old line needed to be abandoned.

Due to construction sequencing, the embankment was already in place well before the water line relocation was performed.

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 cellular grout. Given that the embankment was already in place, the entire 3000LF stretch had to be grouted 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. 2800CY of material were placed over a period of four days onsite with no disruptions to adjacent construction activities.

Garden State Parkway grouting

The Job

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 cellular concrete.

Lightweight Plaza Fill

The Job

Lightweight plaza fill for a private age restricted high rise new build in Tysons Corner, Virginia.

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 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 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 was approximately 2200CY.

Hollow Abutment Filling

The Job

As part of a bridge rehabilitation for MassDOT, two hollow abutments needed to be filled in order to turn the structural approach/departure slabs into slab on grade.

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. In order to reduce the loads applied to the bridge from the backfill, the lightest possible material capable of providing sufficient support to the pavement was required.

Due to integrated beams for the structural slabs, there were 12 different individual pockets which were up to 2′ tall, which had to be vented independently during the final lift, 4 of which had to be under live traffic because the road couldn’t be completely closed.

The Solution

CJGeo worked with the general contractor to formulate a plan to vent the individual pockets from outside of the open lanes, to ensure a complete fill without requiring a complete road closure. Over the course of two mobilizations, CJGeo placed 2,840CY of 25lb/cuft cellular concrete to fill the abutments.

8″ Pipe Abandonment

The Job

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 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.

Union County Annular Space Grouting

The Job

Due to a rapidly increasing population, Union County, North Carolina installed a new raw water intake, which required a nearly 11 mile long raw water line to supply a water treatment plant.

The Challenge

While there were dozens of open cut road crossings along the alignment, 17 crossings were bored, and require annular space grouting per NCDOT requirements. Given the length of the project, there weren’t any ready mix providers who could cover the entire project.

The Solution

CJGeo has multiple NCDOT approved mix designs, CJGeo was able to source material from two different ready mix providers, and grout the annular space on each crossing per NCDOT requirements.

24″ Water Main Abandonment

The Job

As part of a large transportation project, 2000 linear feet of 24″ water main needed to be 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.

The Solution

CJGeo grouted each run of pipe using 30lb/cuft cellular concrete. Each 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.

Grain Silo Tunnel Backfilling

The Job

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

To address the possibility of coastal flooding, the entire structure needed to be constructed above grade, including the 8′ tall unloading conveyor tunnels. The structure was designed to bear 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, which 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 cellular concrete to fill the silo bases up to flush with the top of the unloading tunnel walls. Rodbusters were able to start setting steel the day after completion of the final lift in each of the silos.

Neuse River Annular Grouting

The Job

The City of Raleigh’s Neuse River East Parallel Interceptor project involves the installation of miles of large diameter gravity sewer. Two road crossings required 120″ tunnels for installation of the 96″ HOBAS pipe.

The Challenge

While neither tunnel was very long, due to the 10′ diameter tunnels, grouting needed to be performed in two lifts. This allowed buoyancy control of the HOBAS carrier pipes to be maintained with partial water filling, and eliminated the need to perform hold down blocking during the carrier pipe installation.

The Solution

CJGeo proposed an NCDOT approved cellular grout mix due to passage through an NCDOT right of way, and then grouted the two tunnels each in two lifts. Fill was confirmed with uniform grout vented out the 12 o’clock vent position at the far end of each tunnel.

Dairy Branch Annular Space Grouting

The Job

Charlotte Water’s Dairy Branch Tributary Sewer project is an approximately $30mm capacity improvement project to address increased density.

The Challenge

As part of the project, a 430LF tunnel ranging from 58″ bore to a 4×4 arch was mined. The carrier pipe was 36″ ductile iron, and required annular space grouting using a mix which wouldn’t float the carrier pipe, and would be able to entirely fill the tunnel at low pressure.

The Solution

CJGeo proposed an NCDOT approved cellular grout mix due to passage through an NCDOT right of way, and then placed the 275CY of grout in a single lift over two hours at approximately 5psi of placement pressure.

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