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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SW Florida Annular Space Grouting
The Job
This Florida annular space grouting project by CJGeo is located in For Myers, Florida. The work is part of the City of Fort Myers’s South AWWTF Reclaimed Water Transmission Main. The goal of the project is to facilitate the beneficial reuse of treated wastewater, primarily for uses such as irrigation which historically utilized drinking water.
The Challenge
The majority of this pipeline uses open cut installation. However at two road crossings with extensive existing buried utilities, trenchless installation is most appropriate. The first crossing is 170 linear feet. The second crossing is 607 linear feet. Each tunnel is 52 inches in diameter steel. The reclaimed water line is 32 inch diameter ductile iron pipe.
The Solution
The tunneling contractor for this project was under contract to provide turn key installation, including annular grouting. The tunneling contractor reached out to CJGeo, knowing that CJGeo’s CJFill cellular grout could:
- fill each annulus in a single lift
- not over-pressurize or damage the brand new carrier pipe
- not float the brand new carrier pipe
CJGeo took two days onsite to grout both tunnels (one day per tunnel). The final design for the grout on this Florida annular space grouting project was 38lb/cuft CJFill-Standard, with a 250psi unconfined compressive strength at 28 days. While the Florida DOT’s minimum strength for cellular grout is only 80psi at 28 days, the designer wanted a higher strength grout than the minimum acceptable by the DOT.
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Rising Mains 48″ Abandonments
The Job
This Pittsburgh pipe abandonment project is located within the city of Pittsburgh, Pennsylvania. It is part of the Rising Mains No 3 & 4 replacement project. Plans call for filling with grout roughly 1575LF of 48″ water main.
The Challenge
The abandonment was specified for traditional controlled low strength material (flowable fill). However the contractor had doubts about being able to successfully perform the pipe abandonments with flowable fill. These concerns were based on access limitations, ready mix delivery limitations and the roughly 20′ of elevation change over the length of the pipe.
The Solution
The contractor reached out to CJGeo about using low density controlled low strength material (LD-CLSM). CJGeo evaluated the pipeline as-builts and recommended a CJGeo 25lb/cuft CJFill-Ultra Lightweight cellular concrete mix design. 25lb/cuft CJFill-Ultra Lightweight’s average 80psi compressive strength at 28 days (ASTM C495) is ideal for abandoning the pipes. The low density maximizes yield (finished volume per ton of cement), and provides adequate bearing capacity in most situations.
Using onsite dry batching, CJGeo generated and placed 730CY of grout to successfully fill the pipe, which was access near the middle to create two segments. The work took two days onsite to complete. Onsite batching directly from bulk cement was advantageous on this project for the following reasons:
- economical – it costs significantly less than ready mix flowable fill
- speed – CJGeo made more than 100CY of CJFill-UL per hour
- safety – peak placement pressures were less than ten psi
- logistics – it only took five loads of cement, whereas flowable fill would have taken 92 loads
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Facing a similar challenge to this Pittsburgh pipe abandonment project that CJGeo completed with CJFill-Ultra Lightweight cellular grout? 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.
Utility Tunnel Abandonment
The Job
This utility tunnel abandonment project is located in Wilmington, Delaware. Approximately 750CY of subbasement and utility tunnel had to be filled as part of a commercial building adaptive reuse project.
The Challenge
The structural engineer had two concerns:
- the slab over the basements were to be replaced,
- tunnel walls required bracing to demo the roof slab
- the density of the fill needed to be as low as possible to reduce the chances of inducing settlement.
The Solution
CJGeo proposed 25lb/cuft CJFill-Ultra Lightweight low density controlled low strength material. Low density controlled low strength material is a fancy name for cellular concrete. 25lb/cuft CJFill-UL has an average of 80psi compressive strength. Because CJFill-UL cellular concrete is very mobile, there were no issues with filling the tunnel from just a few access points.
With an average cured unit weight of 21lb/cuft, the using load reducing fill material saved approximately 1ksf in dead load relative to conventional fill materials. CJFill-Ultra Lightweight also provides sufficient strength to brace the walls to facilitate floor removal, and also provide adequate bearing capacity for the new floor.
It took a CJGeo cellular concrete crew two days onsite to fill the tunnel and subbasement. Onsite dry batching made up to 100 cubic yards per hour of the 25lb/cuft CJFill-Ultra Lightweight. Material placement was through 4″ cores and an exterior access areaway.
Other types of lightweight fill would have been much harder to install. Foamed glass aggregate or expanded shale aggregate would be practically impossible to compact given the low headroom. The density of expanded shale aggregate is also relatively high, so would not have offered the load savings that 25lb/cuft CJFill-Ultra Lightweight does. EPS is very lightweight, but is very labor intensive in this type of application.
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Facing a similar challenge to this utility tunnel abandonment 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.
Power Station Pipe Abandonment
The Job
This power station pipe abandonment project is between Richmond & Lynchburg, Virginia, along the James River. Dominion’s Bremo Bluff Power Station was taken off line in 2019. As part of complete decommissioning, demolition and site restoration took place in 2022.
The Challenge
Power stations typically have extensive pipes for cooling water circulation. At Bremo Bluff, the buried cooling pipe network consists for four, four foot diameter pipes, connecting to a junction box. Total linear footage of the forty-eight inch pipes is about six hundred linear feet.
Due to the remote location, the demolition contractor knew that it would be difficult to get timely deliveries of the nearly 40 loads of flowable fill needed to fill the pipes.
The Solution
The demolition contractor reached out to CJGeo for consultation on the best type of flowable fill for the pipe abandonment work. CJGeo recommended 25lb/cuft CJFill-Ultra Lightweight. 25lb/cuft CJFill-Ultra Lightweight has a 28 day compressive strength (ASTM C495) greater than 50 psi. This met the owner’s requirements.
25lb/cuft CJFill-Ultra Lightweight is nearly 80% air content. Therefore, each twenty-five ton load of cement delivered to the site turns into nearly 150 cubic yards of finished product. Due to this on-site expansion, instead of needing nearly 40 loads of ready mix flowable fill, the work only needed two loads of cement.
CJGeo generated and placed approximately 300CY of CJFill-Ultra Lightweight cellular concrete to fill the junction box and pipes. CJGeo made all of the material over a few hours onsite, using dry batch generation.
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Facing a similar challenge to this power station pipe abandonment project? 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.
Lightweight Tank Foundation
The Job
This lightweight tank foundation installation project is located in Baltimore, Maryland. During an industrial facility expansion, a new blending tank was being installed at the top of a retaining wall. In addition concerns about lateral loading on the wall, the area is generally known to be built with uncontrolled fill over compressible soils, so settlement is a concern.
The Challenge
Due to the presence of industrial waste and debris in the area, light duty deep foundations such as helical piles are generally difficult to install. To avoid inducing settlement, the geotechnical EOR reached out to CJGeo for lightweight fill options to net out the increased weight of the mat foundation and blending tank.
Based on loads, CJGeo suggested a 25lb/cuft cellular grout with a compressive strength of at least 50psi. At this density, the engineer was able to balance all loads with a 4′ deep undercut. The undercut extended a few feet out around the perimeter of the tank foundation.
The Solution
First, the concrete foundation contractor excavated the pit. Then, CJGeo mobilized to the site and placed 110CY of 25lb/cuft CJFill-Ultra Lightweight cellular concrete into the pit. The lightweight tank foundation placement took less than an hour. The foundation contractor was able to start setting steel and forms the following morning.
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Facing a similar challenge to the one we solved with this lightweight tank foundation? 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.
Tennessee Annular Space Grouting
The Job
This Tennessee annular space grouting project is located in Brentwood. Brentwood is part of the Nashville metro area, which is rapidly expanding. As part of large water main installation, a 970′ tunnel, ranging from 60 to 78 inch diameter was mined through a small mountain. To ensure long term service improvements, a 42″ DIP water line occupies the tunnel.
The Challenge
The tunnel support is wood lagging, which is not permanent. Therefore, the annular space requires grouting to ensure long term stability of the new water line and adjacent ground.
Because the Nashville market is so hot, it’s really hard to get any concrete deliveries, let alone specialty mixes. The tunneling contractor knew that they would be hard pressed to self-perform the grouting using flowable fill. This was if they could even get material. So, they reached out to CJGeo about performing the annular space grouting with cellular grout made onsite with one of CJGeo’s custom mobile cellular batch plants.
The Solution
CJGeo proposed and installed 25lb/cuft CJFill-Ultra Lightweight cellular grout for the annular space grouting. By generating material onsite directly from bulk cement, using a dry batch plant, the 425CY annular space grouting took fewer than five hours.
Buoyancy control on this project was very easy. Because CJFill-Ultra Lightweight cellular grout is so much lighter than water, filling the carrier with water was sufficient to ballast the pipe against uplift during grouting. No casing spacers or top blocking needed. The American Concrete Institute classifies CJFill-Ultra Lightweight as low density controlled low strength material.
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Facing a similar challenge to this Tennessee annular space grouting project? 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.
Georgia Annular Space Grouting
The Job
This Georgia annular space grouting project is located in Athens, Georgia. The project involves three tunnels connecting four shafts. Tunnel lengths range from 116LF of 700LF, with diameters between 58.5″ ID to 9×9 arch segments.
The Challenge
In order to keep the carrier pipe from floating during grouting, the maximum allowable grout density was 70lb/cuft, and the minimum compressive strength was 200psi. Material had to be highly mobile, to facilitate placement through the 700LF of tunnel.
The Solution
CJGeo proposed 38lb/cuft cellular grout to the tunneling contractor. Over a period of three days, CJGeo batched and placed 1320CY of CJFill-Standard. Batching was performed utilizing an onsite dry mix plant, which was fed directly by bulk cement trailers. The minimizes the required laydown area on a very tight site.
Because of the very low grout density, the carrier pipe buoyancy control was simply water filling.
To address the transition from a round tunnel to an arch tunnel, CJGeo worked with tunneling contractor to design a sacrificial pipe venting system.
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Facing a similar challenge to this Georgia annular space grouting project? 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.
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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Low Level Outfall Abandonment
The Job
This low level outfall abandonment grouting project is located in New Jersey. The Round Valley Reservoir, in Clinton Township, New Jersey is a 2300 acre man-made drinking water reservoir. It serves extensive portions of New Jersey. It was constructed by damming up two openings in a naturally-curved mountain.
As part of a dam upgrade project, a 1400LF, 36″ inner diameter LLO pipe needed to be grouted to place it out of service.
The Challenge
The pipe had been previously blind flanged, 180′ below the lake surface. There was a single, 12″ riser pedestal. There were numerous significant challenges to face, including:
- 2GPM residual leak from the blind flange buried in 15′ of lake floor debris
- inability to push sacrificial pipes more than 500′ up the pipe
- remote site with limited ready mix service
The Solution
CJGeo worked with the general contractor, diving subcontractor, sacrificial grout pipe installation subcontractor, geotechnical and civil EORs, and the owner, to develop a single stage grouting plan to place approximately 350CY of 68lb/cuft CJFill-Under Water cellular grout from the downstream end.
Venting was achieved by installing a 4″ removable vent pipe from the pedestal riser. The vent pipe ran 180VF to the lake surface, terminating on a barge. There was only one opportunity to do the job correctly. Therefore, CJGeo had two fully staffed grout plants onsite, and had all cement and mix water staged in onsite storage. This was all prior to the start of grouting to avoid any material logistics disruptions affecting the work.
CJGeo placed the 68lb/cuft grout over a period of a few hours, leaving an intentional air pocket at the high end to capture infiltrating lake water long enough for the grout to set prior to seeing lake head.
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Facing a similar challenge to this low level outfall abandonment project? 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.
