Nashville Basement Abandonment
The Job
This privately owned building was constructed inside of the basement of a previous building, but with a smaller footprint. Structural slabs were poured spanning between 4′ and 20′ from the original basement walls to the new basement walls.
The Challenge
As the structural slabs over the unused basement deteriorated, there were concerns about stability. Uses included a public sidewalk and parking/driveway area. The wall isolating the occupied space of the new building and the unoccupied area of basement was constructed of hollow clay block, metal studs & drywall. The maximum lateral load of any backfill material could only be 50PSF.
The Solution
CJGeo successfully filled the basement with 775CY of CJFill-UL7.5. The placements was done in 2′ lifts to meet the maximum 50PSF liquid head limit.
Steam Tunnel Lightweight Backfill
The Job
As part of the expansion and renovation of the steam plant at Western Carolina University, a section of existing steam tunnel needed to be uncovered to install a new wall. The wall needed to be backfilled, and due to the condition of the tunnel, the lighter the backfill the better.
The Challenge
The site was exceptionally tight, and the location was more than 30 minutes from the closest ready mix plant. The backfill depth was nearly 15 feet, but the project was only about 1200CY, so doing 2′ lifts would have been slow and expensive.
The Solution
CJGeo proposed a CJFill-UL as a value improvement over the organic foaming agent cellular concrete that was specified. The architect and structural engineer approved the proposed change.
CJGeo mobilized a four person crew and a 200CY/hour mobile batch plant, and completed the work in three pours over two days. The CJFill-UL was generated using a synthetic foaming agent that can be placed up to 20 thick at a time, and is generated onsite directly from bulk cement, so isn’t dependent on ready mix plant locations.
Savannah Tunnel Abandonment
The Job
The JW Marriott Plant Riverside is an adaptive reuse hotel project of a decommissioned power plant in Savannah, Georgia. As a thermal generation facility, there are extensive water tunnels below the structure. The tunnels were cast in place during original construction, and integrated into the pile supported foundation.
The Challenge
As part of the conversion from thermal power generation to luxury hotel, the tunnels needed to be filled. Due to concerns about inducing settlement with traditional flowable fill, the designer specified EPS Geofoam blocks. These would have effectively eliminated loads, but were deemed impossible to install.
The Solution
Someone onsite had heard of cellular concrete, so reached out to CJGeo. CJGeo evaluated the layout of the tunnels, isolation methods from the river, and designed a mix which would ensure both complete filling of the structures without adding any additional load.
CJGeo placed approximately 930CY of 20lb/cuft CJFill-UL cellular concrete over a period of three days. Because CJFill-UL is highly mobile, demo debris from the access holes for building bulkheads was left in the tunnels and encapsulated with the CJFill-UL.
Nashville Basement Backfill
The Job
Nashville Yards is a block-wide new build project in downtown Nashville, Tennessee. With multiple underground levels of parking, the basement excavation is more than 30′ below grade in spots. The excavation walls are a combination of blasted rock and soil nail walls.
The Challenge
The designer wanted to reduce lateral loading on the basement walls as much as possible. Due to the irregular face of the blasted rock & soil nail walls, lightweight aggregate would have been very difficult to install and compact, and would have applied lateral loads for the life of the structure. Flowable fill would have been easy to install, but applied too much lateral loading during installation if done in practical pour volumes.
The structural engineer determined that 25lb/cuft cellular concrete would be the best backfill material. The project volume was approximately 1500CY, and the maximum fill depth was 30′.
The Solution
CJGeo mobilized a mobile batch plant which uses colloidal mixing to the site. Due to the extremely high quality mixing, the crew placed CJFill-Ultra Lightweight up to 10′ deep per pour. This included three pours 10′ deep and 250CY each.
8′ CMP Joint Grouting
The Job
A spec warehouse was planned for a vacant piece of land which had 1700LF of 8′ CMP running through it. The pipe was installed when the site was first prepped, approximately 10 years prior to construction. Because the site was vacant, there was no maintenance. Nearly every joint showed signs of soil infiltration, and there were massive sinkholes along the entire alignment.
The Challenge
To avoid having the replace the entire run of pipe, the joints needed to be sealed. There were 80 pipe joints and 12 pipe to structure joints that were affected.
The Solution
CJGeo mobilized a polyurethane grouting crew to the the site. Over the course of a week onsite, the crew sealed all of the joints. As part of the joint sealing, the voids around the pipe were filled with CJGrout 20SDB geotechnical polyurethane. After the grouting work was done, the site contractor backfilled the sinkholes and washouts with soil.
Medical Clinic 3′ Void Fill
The Job
The medical clinic on a military base was being renovated. As part of the renovation, the 650sqft elevated slab front porch needed to be replaced. The slab “sounded hollow,” and the presumption was that there were nominal voids below the slab.
The Challenge
At the start of demolition, the demolition contractor determined that the voids below the slab were closer to 3′ deep. This presented a safety problem for the demolition. The concern was that the slab would fail catastrophically during demolition. The general contractor reached out to CJGeo about ways to reduce the void depth.
The Solution
CJGeo proposed void filling below the slab using CJGrout 20SDB. CJGrout 20SDB is a low exotherm bulk void filling geotechnical polyurethane specifically formulated for deep fill placements without scorching or charring. A two person crew mobilized to the site and placed approximately 2,900lbs of CJGrout 20SDB in a few hours onsite, allowing the demolition contractor to safely resume work.
Industrial Basement Abandonment
The Job
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 needed 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, able to be placed in deep lifts, and as light as possible.
Fill density was a concern because the basement was up to 15′ deep. The structural and geotechnical consultants were concerned about inducing settlement if flowable fill (typically around 150lb/cuft) was used.
The Solution
CJGeo proposed 25lb/cuft cellular concrete for the fill material. Using onsite colloidal batching, CJGeo can place material up to 20′ deep in a single lift, without consolidation. Because the material is so lightweight, the entire 15′ deep basement could be filled for the same dead load as just two feet of flowable fill.
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. Without being affected by trucking or cement supply chain disruptions, CJGeo started placing immediately. Over four days onsite, CJGeo place 2700CY of material.
Warehouse Floor Joint Stabilization
The Job
About two months after occupying a new warehouse in Ashland, Virginia, the tenant identified two joints where the floor “popped” at a joint when a forklift drove over them. After consulting the plans, the owner determined that the joint wasn’t doweled.
The Challenge
Both affected joints were on main, high frequency travel pathways within the warehouse. So, any repairs had to be done quickly, and with zero impact to operations.
The Solution
CJGeo proposed undersealing the two joints, which had experienced slab curl, with high density geotechnical polyurethane grout. In fewer than three hours onsite, CJGeo undersealed the joints with CJGrout 20SDB, load tested them, and demobilized. There were no impacts to operations of the facility.
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.
