Upham Brook Annular Space Grouting
The Job
This Upham Brook annular space grouting project is located in central Virginia. A sewer trunkline expansion in Richmond, Virginia required five bored road crossings ranging from 60″ to 72″.
Tunnel lengths are from 200LF to nearly 600LF. Mining is through rock using slurry micro-tunneling. One tunnel had mixed face conditions, which was unanticipated.
The design engineer required cellular concrete for annular space grouting due to run length, and buoyancy control of the carrier during grouting.
The Challenge
Not many; the longest run on this project, 600LF is a relatively short distance to push cellular concrete. Three of the four tunnels are round. The fourth tunnel is a combination of a round, MTBM-mined tunnel that transitions to a hand mined arch. The hand mine arch was to rescue the MTMB, which became stuck under a triple track CSX rail line. There was very poor access (the rescue shaft is in the CSX right of way).
The Solution
CJGeo proposed 38lb/cuft non-permeable CJFill-Standard low density controlled low strength material to meet the designer’s 200psi 28-day compressive strength requirement.
Over four different mobilizations, CJGeo successfully placed approximately 900CY of annular space grout.
The LD-CLSM generation was wet batch. Wet batch generation was chosen due to the relatively small daily volume of material placement and very tight sites.
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I-66 Annular Space Grouting
The Job
During the widening of Interstate 66 near the interchange with US-15, nine new culverts were installed by jack and bore, and one via direct jacking. The carrier pipes were a mix of spiral metal, precast concrete, and corrugated HDPE, and ranged in length from 150 to 350 feet.
The Challenge
The contractor, who was responsible for grouting, was concerned about carrier pipe buoyancy during grouting, and also run length. All work had to be done from one side of the interstate highway (three lanes in each direction, plus full-width shoulders and a median strip), as there was no access on the far side.
The Solution
CJGeo proposed 30lb/cuft CJFill-Ultra Lightweight cellular concrete for the annular space grouting mix design. Cellular concrete is the preferred material for annular space grouting because it is highly flowable, and reduces the chances of damage to carrier pipes in long placements. Its low unit weight also reduces carrier pipe buoyancy. CJGeo placed 350CY of cellular grout to successfully complete the jack and bore annular space grouting over three different mobilizations.
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CPVC Annular Space Grouting
THE JOB
This CPVC annular space grouting project is located in Leesburg, Virginia. Leesburg is outside of Washington, DC, and is a rapidly growing suburban community experiencing explosive growth of data centers, which is driving similar growth in water infrastructure. During the construction of commercial development, a 200LF of 16″ CPVC waterline was installed via jack and bore, through a 36″ casing. The casing crosses a suburban collector road, which is six lanes wide.
THE CHALLENGE
Due to site limitations, only one end of the pipe was accessible for grouting. The length of the placement was approximately 200LF. So, grout had to travel 200LF at low pressure while ensuring a complete fill without damaging the delicate carrier pipe material.
CPVC is relatively sensitive to heat of hydration, particularly when compared to ductile iron and fiberglass pipe materials.
THE SOLUTION
Due to the relatively low volume, and heat sensitivity of the pipe, CJGeo proposed performing this CPVC annular space grouting with wet-batched 30lb/cuft CJFill-Ultra Lightweight low density controlled low strength material.
To control carrier pipe buoyancy during grouting, the jack and bore contractor filled the CPVC pipe with water. This was accomplished by using pipe plugs. To address the inaccessible vent end, the customer stubbed a vent pipe to the surface prior to backfilling the bulkhead.
A CJGeo CJFill cellular grouting crew took less than one day to complete the grouting. Confirmation of will was venting of uniform material from the far end vent pipe.
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HDPE reline annular space grouting
THE JOB
A utility contractor installing 500LF of 48″ HDPE reline pipe through a 63″ CMP culvert required annular space grouting done at very low installation pressure yet able to ensure complete filling of the washouts outside of the CMP. This HDPE reline annular space grouting project is located in Baltimore, Maryland.
THE CHALLENGE
Due to traffic control limitations, only one end of the pipe was accessible for grouting. Therefore, all grout installation was done with up to 200LF of pumping to get to the bulkhead and then up to 500 feet of travel through the annulus via sacrificial grout tubes. Bulkhead leaks usually result from extensive voids outside of the host pipe. This pipe’s invert corrosion posed unique challenges for containing the annular space grout. CJGeo proposed cellular concrete for the annular space grouting. Cellular concrete is highly flowable. High flowability ensures low installation pressure, reduces flotation of lightweight carrier pipes, and ensures complete void filling outside of the host pipe. Using cellular concrete for annular space grouting was specified by the HDPE slip lining pipe manufacturer.
THE SOLUTION
CJGeo successfully performed this HDPE reline annular space grouting project over two days, in two lifts. Multiple lifts reduce the heat of hydration and carrier buoyancy. The cellular concrete-filled all of the voids outside of the host pipe. The peak pressure at the pump did not exceed 15PSI throughout the project. Therefore, the project was successfully completed without floating, deflecting, or damaging the HDPE slip line pipe.
CJGeo placed 30PCF wet cast density CJFill-Ultra Lightweight, with a 125psi compressive strength for this project. With a 24 hour penetration exceeding 50psi, 30PCF cellular grout reduces buoyancy with its low unit weight, provides adequate strength, and rapid stability.
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North Jersey Annular Space Grouting
THE JOB
This North Jersey annular space grouting project is located in Paterson, New Jersey. A 30″ brick sewer in New Jersey started to unravel during an open excavation point repair. The municipal engineer directed the utility contractor to use welded HDPE pipe to reline the sewer instead of finishing the open cut point repair.
THE CHALLENGE
The HDPE slip lining contractor had four requirements for grouting:
- No more than 10psi grouting pressure, as measured at the bulkheads
- A mix which minimized carrier buoyancy
- Three day turnaround from notification to completion
- 200psi strength at 28 days
THE SOLUTION
CJGeo proposed 38PCF wet cast density CJFill-Standard cellular concrete for the annular space grouting. Cellular concrete is highly flowable. High flowability ensures low installation pressure. 38PCF cellular concrete reduces exerts 60% less buoyancy force compared to traditional weight grout. 38PCF cellular concrete reaches approximately 250psi at 28 days, when generated through the ready mix supply chain.
CJGeo mobilized to the site with two days’ notice. The CJGeo cellular concrete crew used continuous generation to generate and place the 38PCF cellular concrete to complete this North Jersey annular space grouting project. Peak pressure at the bulkheads never exceeded 5psi. All 500LF of the annulus was grouted in a single day, between four different manholes (three sections).
Confirmation of fill was uniform material venting at each bulkhead.
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Virginia Annular Space Grouting
THE JOB
1100 feet of pile-supported 34″ PCCP water line over a drinking water reservoir was being slip-lined. This Newport News, Virginia annular space grouting project was specified by the designer to use cellular concrete. The relining contractor used 30″ welded HDPE for the slip line, which then required annular space grouting.
There were multiple leaks at the joints between the PCCP sticks. Work was complicated by a seasonal light display, which limited access hours to the job site.
THE CHALLENGE
The designer specified 55PCF wet cast density CJFill-Standard cellular concrete for the annular space grouting. Cellular concrete is highly flowable. High flowability ensures low installation pressure, reduces flotation of lightweight carrier pipes, and ensures complete void filling outside of the host pipe. Using cellular concrete for annular space grouting was specified by the HDPE slip lining pipe manufacturer. Buoyancy control was by water fill of the carrier pipe.
Nearly every joint on the pipe was leaking. Each joint had to be grout tight prior to starting the grouting process.
THE SOLUTION
All venting was over water. CJGeo completed this Virginia annular space grouting project without introducing any contaminants to the drinking water reservoir.
The 55PCF cellular concrete provided a break strength of approximately 700psi at 28 days. Peak installation pressure was 18psi. The crew used wet batch generation due to the relatively low volume.
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Maryland Annular Space Grouting
THE JOB
A jack & bore contractor performed a 200LF, 54″ bore under an arterial highway. After sliding in a 48″ RCP carrier pipe (stormwater), the annular space required grouting. This Maryland annular space grouting project is located in Jessup.
THE CHALLENGE
Due to size limitations, only one end of the pipe was accessible for grouting. The length of the placement was approximately 200LF, so grout had to travel 200LF at low pressure while ensuring a complete fill.
THE SOLUTION
CJGeo proposed cellular concrete for the annular space grouting. Cellular concrete is highly flowable. High flowability ensures low installation pressure, reduces flotation of lightweight carrier pipes, and ensures complete void filling outside of the host pipe.
CJGeo successfully performed this Maryland annular space grouting project in a single day using CJFill-Ultra Lightweight cellular concrete. The peak pressure at the pump did not exceed 5PSI throughout the project.
Due to the relatively low volume, CJGeo used continuous wet batch generation for making the cellular concrete. With continuous wet batch generation, a ready mix company delivers the slurry. The ready mix truck discharges into a grout pump, and CJGeo injects the preformed foam continuously in line downstream of the pump.
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Fullerton Reservoir Annular Space Grouting
THE JOB
This reservoir annular space grouting project is located in Baltimore, Maryland. As part of the construction of a new drinking water reservoir for Baltimore County, Maryland, 140LF of 30″ jack & bore with a 12″ DIP water line and two 4″ PVC conduits required annular space grouting.
THE CHALLENGE
Due to the relatively long run and delicate PVC carrier pipes, CJGeo proposed using foamed concrete for the annular space grouting. 45lb/cuft CJFill-Standard cellular concrete generated using Aerlite preformed foam was proposed to achieve the owner’s requirement of 250psi at 28 days.
Carrier pipe buoyancy control is one of the most difficult elements of small diameter annular space grouting. In very large diameter placements, multiple lifts are practical, but in small diameter pipes, generally aren’t possible. When multi-lift grouting isn’t practical, having a grout density less than water (about 60 pounds per cubic foot) facilitates single lift grouting as long as the carrier pipes are full of water.
THE SOLUTION
In a short morning, they generated and placed 31 cubic yards of CJFill-Standard cellular concrete to successfully grout the annulus. Peak pumping pressure was less than 5psi. Confirmation of a complete fill was uniform material discharging from the 12 o’clock vent at the opposite end from placement.
Because the grout density was significantly less than the density of water, filling the carrier pipes with water controlled all buoyancy.
28 day breaks confirmed that CJGeo exceeded the break strength requirement.
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Communication Jack & Bore Grouting
The Job
The Sandston area, just outside of Richmond, Virginia, is at the crossroads of major north/south data transmission lines, and transoceanic data transmission lines. This jack & bore grouting was done to support a road crossing connecting two new data centers.
The Challenge
As part of the construction of a new, multi-billion dollar data center, a utility contractor bored two, 48″ steel casings under a roadway & adjacent wet utilities for a road crossing. Each of the casings had up to 20 different PVC conduits held in place using casing spacers. The contractor needed a grout that could be placed at minimal pressure while ensuring complete fill without damaging the conduits.
To avoid carrier pipe buoyancy, the maximum allowable grout density for the annular space grouting was 45lb/cuft.
The Solution
CJGeo mobilized a cellular grouting crew to the site and did the jack & bore grouting on both pipes in a single day. The peak grouting pressure was 5psi, and confirmation of fill was achieved when uniform cellular concrete was vented from the 12 o’clock position on the opposite end of each bore. 38PCF CJFill-ST was used to achieve the design strength of 200psi at 28 days.
CJFill-ST is heavier than CJFill-Ultra Lightweight, which is the most common cellular grout that CJGeo uses for annular space grouting. However, in the case, the municipality specified a higher compressive strength due to the proximity of multiple other critical utilities.
CJGeo used wet batch on this project due to the low volume and proximity of a ready mix plant. Wet batch typically has lower peak heat of hydration, which is helpful when grouting around PVC.
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Microtunnel Annular Space Grouting
The Job
This microtunnel annular space grouting project is part of a massive interstate expansion project in Charlotte, North Carolina. Seven micro tunnels were mined under I-77 to convey various utilities below the highway. Microtunneling was used, with casing diameters of 60″, along with a hand-mined tunnel lined with an 84″ tunnel liner plate.
Due to the length of runs, volumes required and strict NCDOT mix design requirements, the tunneling contractor reached out to CJGeo to explore cellular concrete as an option for the microtunnel annular space grouting.
The Challenge
CJGeo proposed performing the annular space grouting using 30lb/cuft cellular concrete. CJGeo has approved NCDOT mix designs for cellular concrete, which helped facilitate expedited submittal processing.
Cellular concrete was also advantageous from a carrier buoyancy perspective. The carrier pipes installed in each of the tunnels were all negatively buoyant in the grout. This helps to ensure proper alignment and minimize any chances of damage during grouting.
The Microtunnel Annular Space Grouting Solution
During the first mobilization, CJGeo placed 630CY of CJFill-Ultra Lightweight cellular grout to grout the two tunnels over a period of three days. The 60″ tunnel was grouted in a single lift, the 84″ tunnel was grouted in two lifts.
Confirmation of complete fill was through venting of uniform cellular concrete at the far ends of each tunnel. Additionally, the 84″ tunnel liner plate structure had cellular concrete weeping out of the bulkhead on the exterior of the plate. This indicates that the cellular concrete had exfiltrated through the liner plate joints and was flowing outside of the liner plate.
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