Railroad Bore Annular Space Grouting
The Job
This railroad bore annular space grouting project is located in Winchester, Virginia. As part of a new development, three parallel stormwater pipes were bored under a CSX right of way.
The Challenge
The railroad requirements include annular space grouting. The three casings (80 feet long each), are 48″ by 0.725 wall thickness steel. The carrier pipes are 30″ N-12 pipe, with a 35.50″ outside diameter.
This annulus requires about 16 cubic yards of grout per bore. One of the challenges of double wall HDPE drainage pipe is that it is exceptionally light. This can make uplift management during grouting particularly challenging.
The Solution
In order to manage buoyancy during the annular grouting, the boring contractor installed longitudinal blocking on each of the carrier pipes during installation. To reduce the uplift by six times compared to flowable fill, CJGeo proposed a 30lb/cuft cellular grout for the annular grouting.
Between the blocking and the very low density CJFill-Ultra Lightweight cellular grout, single lift grouting was possible without damaging the new carrier pipes. Single lift grouting eliminates the risk of trapped air pockets or partial fills associated with multi-lift grouting.
Due to the relatively low volume, and to reduce heat of hydration, wet batch generation using slurry from a local ready mix plant was used.
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Tunnel Adit Fill
The Job
This tunnel adit fill project is part of the Purple Line project outside of Washington, DC. Specifically, the adit is located at the pedestrian connection between the Purple Line project and WMATA’s Bethesda station on the Red Line.
The Challenge
Plans call to connect the Purple Line to the Red Line using an adit constructed during the original construction of the Red Line. The adit is approximately 30 feet wide by a 35 foot tall arch. During preparation to blast from a shaft dropped adjacent to the station, a fault was identified passing through the adit.
The construction and design teams were concerned about stability of the adit during blasting operations as the Purple Line access tunnel was excavated towards it. The team determined that filling the adit to plug and stabilize it during blasting would be the most risk appropriate move.
Filling the adit would fulfill the design challenge of stabilizing the rock during blasting. However, it created the following challenges:
- the tunnel adit fill material would need to be removed after blasting was completed
- the adit is approximately 100 feet below grade
- there is very limited space up top
- material couldn’t segregate, and had to be pumped approximately 250 feet in addition to the 100 foot drop
The Solution
The tunnel engineer of record recommended CJGeo to the contractor. The EOR is familiar with CJGeo’s cellular concrete generation and placement expertise, and thought that cellular concrete would be the lowest risk way to fill the adit, while facilitating excavation and removal afterwards.
CJGeo took five days onsite to fill the adit, in lifts up to eight vertical feet. Due to the potential dead load from the rock cover, 400psi CJFill-Standard was the material of choice. By using our colloidal mixing dry batch process, the material set off quickly, ensuring that it would not consolidate during cure as lower energy mixing methods can suffer from.
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Maryland Concrete Lifting
The Job
This Maryland concrete lifting project is located in Frederick, Maryland. The project is for the MARC system, on tracks also used by CSX.
The Challenge
MARC’s Brunswick Line includes a spur to Frederick, which utilizes a freight track that also serves multiple industrial sites, including quarries and concrete plants. As it winds through an industrial area towards the Frederick station, the line crosses multiple arterial roadways. As Frederick grows, traffic is increasing significantly with both cars and industrial truck traffic.
At two crossings, bellies have developed in the precast modular grade crossings. Water collects at the low spots, which then reduces bearing capacity of the base, causing deterioration of the adjacent asphalt pavement. This deterioration causes spalling of the panels, and ride quality problems for motorists.
The Solution
CJGeo’s rail grouting experience includes dozens of precast modular grade crossing stabilization projects. Working with the rail system’s on-call MOW contractor, a CJGeo polyurethane grouting crew grouted each of the two crossings in a day, each.
CJGeo uses CJGrout 48NHL, which is specifically formulated for high dynamic load applications. 48NHL provides multiple factors of safety from a compressive strength perspective, but is slightly elastomeric, which makes it much more durable than mudjacking or traditional cementitious pressure grouting grouts sometimes used to stabilize modular grade crossings on a temporary basis.
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NY Grade Crossing Repair
The Job
10 panels of StarTrack modular grade crossing tubs settled in an urban street crossing owned by a short line. As a result of the settlement multiple clips broke. This caused the panels to pump.
The Challenge
The crossing tubs settled, and when crossed by trucks, pumped water containing the sub-ballast up between the tubs and adjacent pavement. The adjacent track also settled significantly.
The Solution
CJGeo proposed grouting immediately below the panels, and also into the underlying disturbed subballast using CJGrout 48NHL geotechnical polyurethane grout.
The CJGrout 48NHL was injected through 5/8″ holes drilled through the panels. The settlement pattern of each panel determines the specific hole spacing. It takes about five minutes for the grout to cure to 95% of its ultimate strength. After grouting, it’s important to tamp the approaches. Because the rails are clipped, lifting the panels lifts the rails & ties in the approaches. If the approaches aren’t tamped, the crossing can teeter totter, which is bad. Tamping is done immediately after grouting, and preferably before any rail traffic resumption.
CJGeo performed the StarTrack modular grade crossing repair without impacting rail traffic. The facility was able to function normally throughout the repair, which took less than a day.
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New York Tub Crossing Lifting
The Job
Eight panels of StarTrack modular grade crossing tubs settled. As a result of the settlement multiple clips broke. This tub crossing lifting project was for a short line serving an industrial facility in Geneva, New York.
The Challenge
The crossing tubs settled, and when crossed by trucks, pumped water containing the subballast up between the tubs and adjacent pavement. The crossing was the only entrance into an industrial facility that took two trains per day. Because of limited onsite storage, rail service couldn’t be disrupted at all.
The Solution
CJGeo proposed grouting immediately below the panels, and also into the underlying disturbed subballast using CJGrout 48NHL geotechnical polyurethane grout. CJGeo performed the tub crossing lifting work without impacting rail traffic, and the facility was able to function normally throughout the repair, which took less than a day.
Polyurethane grouting with CJGrout is an excellent alternative to cement based grouting, because:
- CJGrout cures within a few minutes, so there are no limitations on rail traffic
- CJGrout is not brittle, so does not break down in dynamic environments like thin layers of cement-based grout tend to do
- CJGrout application is not weather dependent; in this case, it was snowing during installation
- CJGeo controls the entire CJGrout logistics process, so there’s no need to wait on ready mix trucks or coordinate deliveries of material that goes bad within a few hours of offsite mixing
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Chicago polyurethane grouting
The Job
This Chicago polyurethane grouting project is located at BNSF’s Willow Springs Intermodal yard, a critical facility in United States’ freight rail network. The facility is colocated with a large UPS trucking operation. BNSF has very tight time lines for transferring containers from inbound trains to UPS. There are dozens of crossings within the facility, which is primarily concrete pavement.
The Challenge
80 StarTrack modular grade crossing panels across 10 different crossings in the facility experienced settlement. The settlement was affecting the safe operation of yard trucks, causing delays in container transfer times.
Because of the 24/7/365 operation, and very tight performance times, there was no tolerance for downtime.
The Solution
CJGeo proposed grouting the affected panels with CJGrout-48NHL. 48NHL is best for differential settlement correction in high load applications, such as heavy haul rail. It cures within a few minutes, which allows immediate resumption of rail traffic and truck traffic.
CJGeo mobilized a polyurethane grouting crew with extensive modular grade crossing repair experience and grouted the 10 crossings over a period of five days onsite. This Chicago polyurethane grouting project did not affect rail traffic, yard truck operations, or performance metrics.
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New Jersey Grade Crossing Stabilization
The Job
This grade crossing stabilization project is located in Edison, New Jersey. A precast modular grade crossing (Oldcastle StarTrack) crossing developed significant pavement deterioration. NJDOT directed the railroad to stabilize and lift the panels and then patch the adjacent asphalt.
The Challenge
The grade crossing sees up to 8 trains per day (heavy industrial service), and crosses a four lane arterial highway. So, there wasn’t any allowable downtime. Because of this, traditional cementitious grout was not a viable option. Cementitious grouts generally need hours to reach strength, so can significantly disrupt train schedules, and require long lane closures for vehicles.
The Solution
CJGeo proposed grouting the panels using CJGrout 60NHL. 60NHL is a geotechnical polyurethane grout specifically formulated for heavy applications such as rail and aircraft loads. A CJGeo polyurethane grouting crew mobilized to the site and in fewer than 2 hours onsite restored the affected panels. Another name for this process is concrete raising.
This grade crossing stabilization project did not require ground improvement grouting. The cause of the settlement was the bedding fines washing out, so only shallow grouting was necessary.
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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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North Carolina Tub Crossing Repairs
The Job
This tub crossing repairs project is located in Charlotte, North Carolina. Fifty two OldCastle StarTrack panels at four different grade crossings settled to the point of requiring slow orders at the crossings. In order to restore the track to normal speeds, the settlement had to be corrected.
The Challenge
Due to scheduling constraints with rail traffic, with very short windows on weekend nights, the owner elected to have the repairs completed during a single weekend shutdown period. While this allowed for longer work periods, it also meant that four crossings needed to be repaired in fewer than 24 hours.
The Solution
CJGeo mobilized two polyurethane grouting crews to the system, and grouted two crossings each during two shifts. All 52 of the panels were stabilized and lifted back to grade using CJGrout 48NHL, which allows for immediate resumption of rail traffic, from light rail to heavy haul.
Polyurethane grouting is also sometimes called structural polymer grouting. Regardless of name, the process works very well where fast return to service is important. In the case of tub crossing repairs, grout must set very quickly in order for rail traffic to resume. CJGrout 48NHL achieves 95% of its ultimate strength in fewer than 15 minutes.
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Rail Bridge Pier Stabilization
The Job
This rail bridge pier stabilization project is located adjacent to the Congaree National Park. This project was a capital repair to a bridge pier for a Class I railroad. The rail line serves the Port of Charleston, SC.
The Challenge
The Congaree River south east of Columbia, South Carolina frequently sees high flow events, inundating the surrounding low country. At the transition from timber trestle to a bridge, the first bridge pier was originally constructed of stone. The pier bears on a timber mat with timber pile supports. Over time, the river channel migrated and began to expose the timber substructure and scour below the pier.
The nearest road was more than four miles away through impassible swamp. So, all work had to be performed from the river. All material had to be pumped across the bridge, a distance of approximately 600 feet. Due to the compressive nature of the underlying materials, any backfill material needed to be as light as possible. But, due to the high likelihood of flooding, couldn’t contribute significant potential uplift.
The Solution
To address the scour, minimize additional load to the underlying soils, and ensure long term stability of the structure, a third party consultant designed a two tier sheet pile jacket for the structure. They specified the backfill material as 65lb/cuft cellular concrete for the lower segment. And, approximately 45lb/cuft cellular concrete for the upper segment.
CJGeo designed mixes which would meet these requirements:
- be pumpable 600LF,
- tolerate the high vibration environment from the more than 12 trains per day, and
- facilitate a short installation timeframe.
After the general contractor installed the first level of sheet piling and dewatered the area, CJGeo placed approximately 150CY of 65lb/cuft CJFill-Under Water material. Next came installation of the second, smaller diameter sheeting ring. CJGeo then filled the annular space between it and the necked down pier with 45lb/cuft CJFill-Standard material.
CJGeo generated and placed all of the CJFill low density controlled low strength material over a period of four days onsite.
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