Colorado Bridge Approach Slab Settlement Lift

Bridge Approach Slab Settlement Repair – Crystal Valley Parkway, CO

Asphalt Pavement Lift of a Bridge Departure where the Subgrade had settled and the pavement needed to be lifted

In Castle Rock, CO, along the Crystal Valley Parkway, the Town of Castle Rock, CO was experiencing bridge approach slab settlement of 1,900 SF of bridge approach, departure, and sleeper slabs on two bridge ends and adjoining pavement. Settlement of adjacent sidewalk had also occurred causing an unsafe driving situation as well as dangerous conditions to pedestrians utilizing the crossover sidewalk area. The unstable subgrade reaching below the sleeper slab would need to be treated to stabilize the area before mill and fill of asphalt pavement could be performed.

Bridge Approach Slab Settlement Solution

CST partnered with the Town of Castle Rock, utilizing their Deep Injection process to treat unstable soil, lift the slabs, and realign sidewalk and pavement areas. Dynamic Cone Penetrometer soil tests were performed to correctly identify the weak soil zones. Injection tubes were placed at depth and expanding structural polymer injected to densify and provide stabilization of subgrade soils. Once the soil is stabilized, injections are continued to provide lift and realignment of the slabs and overlying pavement. The CST Deep Injection process provides proper support to the soil and heavy sleeper slabs to mitigate against future bridge approach slab settlement and movement, while also providing a solid subgrade for pavement.

Repairs were made in two shifts while allowing traffic to continue utilizing the area vs. time and money spent to reroute. Foundation soils were significantly strengthened to mitigate against future settlement. Bridge approach and departure slabs were lifted back to original elevation as well as stabilization and lift of sidewalk areas. Subgrade soils were quickly and effectively stabilized to provide a strong base for asphalt pavement mill and fill operations. The added benefit of water cutoff effectively arrests soil erosion within the area. Significant savings to municipalities and tax payers vs. alternative methods of rip out and replace. Extended use life of the bridge, sidewalk, and pavement.

Douglas County Sheriff MSE Wall Repair – Highlands Ranch, CO

Douglas County Sheriff MSE Wall Repair – Highlands Ranch, CO

Concrete Stabilization Technologies, Inc. partnered with the Douglas County Facilities Management division of Douglas County, CO to stabilize the MSE walls at the Douglas County Sheriff Sub-Station in Highlands Ranch, CO.

CST was referred by a geotechnical engineering firm to provide a solution to stabilize portions of distressed MSE wall. The geotechnical report indicates low density soils between base of wall and top of storm sewer pipe installed approximately 16’ prior to MSE wall. A section of the MSE wall was slated to be rebuilt after soil stabilization project was completed.

Patented processes were used to increase bearing capacity and stabilize the West and East MSE wall in the sewer trench area of the facility for an area of approximately 60 LF. CST’s deep injection method was performed to reinforce low density soils between top of storm sewer pipe and bottom of MSE wall. The distressed MSE wall was monitored with laser levels during the injection of expanding structural polymer into the underlying soils. Injections were also performed around a manhole to void fill and seal joints.

Video camera inspections were done before and after injection to verify pipe condition. The patented injection processes used in this stabilization project saved the customer from excavating and possibly replacing the pipe.

This project was completed on time and on budget!

CDOT HWY 52 CMP Rhabilitation – Hudson, CO

The Problem

The deterioration of Corrugated Metal Pipe, (CMP) at the flow line is a result of exposure to oxygen and moisture mixed with metal, which causes rust. Other factors such as soil conditions and the acidity of the water flow will also affect the rate of deterioration.

When CMP deteriorates, water runs under the pipe instead of through and undermining of the structure occurs. Sink holes above the structure will begin as the soil collapses. The underlying bedding material or support fill is then exposed to water flow, and begins to erode away, causing voids and loss of structural support. This creates a potentially dangerous situation with the possibility for failure of the entire structure and collapse of the overlying roadway.

Concrete Stabilization Technologies, Inc.’s Field Consultant, Richard Hess was contacted by Colorado Department of Transportation Maintenance Department representative for Region 4, Zach Junk, concerning a deteriorated culvert beneath Colorado State highway 52 near Hudson, Colorado. The traditional method of tearing out and replacing eroded culvert pipe had proven to be a time consuming and disruptive process which had lead CDOT to seek a less disruptive solution.

The Solution

CST met on site with Mr. Junk and after reviewing the area, determined that our CMP repair process was an ideal fix for this particular culvert and overlying roadway. Subgrade stabilization injections from the roadway surface were included in the repair plan where exfiltration of soils through the rusted out pipe had caused variable settlement in the road surface above the culvert, requiring steel plates as a temporary fix against further damage to the road surface and vehicles. Thus, part of the CST complete solution was to not only secure the metal sheets to the old CMP but to also inject from the road surface above to 3′ to 4′ to reinforce the subgrade while replacing soil lost to exfiltration.

CDOT maintenance representative Zach Junk stated that he, “liked the fact that they didn’t have to close the road or detour traffic like they normally do when having to replace pipe.”

Structural integrity of the existing pipe was a concern and it was discussed that not only would the structural integrity of the pipe be restored, but also restoration of correct flow into the repaired pipe.

The ditch company expressed concern of subsequent debris buildup such as weeds and silt that may disturb the water flow. The repair design and installation is such that this concern is positively addressed and re-establishes water flow with no added obstruction.

After an in depth investigation and review of the site, it was assured that this would be an ideal repair process for the deteriorated culvert and CST was given the approval to begin the project.

Crews arrived on the job site around 10:00 a.m. to begin repairs. A significant amount of water was running in the ditch containing the culvert. While water was shut down, crews began deep injection to stabilize the sub-grade on the overlying roadway. Injections were made from the surface at a depth of approximately 3 ½ feet on 5 foot centers, while monitoring at the surface for move-ment. After the subgrade stabilization was complete, it was determined that one of the two overlying road lanes was in good shape and the other lane would only require select asphalt patching once repairs were complete.

The Results

Neither lane required any excavation during repair, due to CST’s unique in situ polymer injection process. Once stabilization of the roadway was complete, the crew began repairing the corrugated metal pipe. Repairs and cleanup were completed in one working shift. The Frico Ditch Company representative confirmed that “the ditch is flowing well”.

Benefits of CMP Repair

The patented CMP repair process is quick and non-disruptive. The pipe is first cleaned of any sticks, rocks, and other debris. Repairs begin on the outlet-side of the pipe where the new sheets of specially coated metal are laid, ensuring the corroded water line is covered. The metal sheets are then attached to the ribs of the pipe with corrosion resistant fasteners. Overlapping sheets are then continuously added and secured in place until the length of the pipe is completely reinforced. In this case, the culvert being repaired was approximately 50 feet long and 5 feet in diameter with the corrosion/water line reaching approximately one third of the way up the side wall of the culvert. Once the new metal sheets are all placed, and secured, expanding structural polymer is injected beneath the metal sheets, to fill any voids beneath the pipe. Excess material is removed and a tar coating is applied to the top edge of the new metal sheeting as an extra protective measure to deter rusting and to ensure longevity.  The benefits include:

  • No-excavation
  • Less disruptive
  • Reduces costs
  • No road or rail closure or downtime
  • Repair equipment & material are easily mobilized
  • Extends lifetime of invert
  • No loss of flow
  • Environmentally inert materials
  • Completely restores structural integrity

 

Middle School Chiller Lift – Denver, CO

A Denver, Colorado, middle school experienced the effects of expansive soil on a pair of large, 16 ton ice chiller thermal storage units used for numerous school refrigeration needs. Each storage unit was placed on independent, 32,000 lb. reinforced concrete pads to maintain a continuous, even elevation for support and proper unit function. Substantial damage and malfunction to each unit was highly probable if the supporting concrete pad was uneven.

Expansive soils shifted beneath the concrete support pads causing an unsatisfactory level for the chiller units to continue functioning. To avoid damage to the units, both were taken out of service until a repair plan was initiated. The concern for the school district was to have the chiller units functioning at capacity, supported on level concrete pads in time for the upcoming school year.

Due to the cost and downtime for the school and potential hazard of damaging each unit through relocation, a choice was made to use a high-density, polyurethane grouting technique. CST’s Deep Injection Process densifies weak soil zones at specified depths to resupport each pad. This process solved three main concerns:

  1. Eliminate relocation of the units
  2. Stabilized volatile soils
  3. Level the units to 3/4” tolerance to restore functionality and capability.

After elevation profiles were taken, injection locations were determined to stabilize weak soil strata and realign the chiller units. Operators injected at depths of 3 feet at an angle to allow greater material coverage for maximum unit stability.

After stabilizing the weakest soil zones, additional injections realigned the pads within the 3/4” tolerance for the ice chillers to function properly without damaging each unit.

Jefferson High Foundation Settlement – Edgewater, CO

Concrete Stabilization Technologies, Inc. worked with General Contractor Saunders Construction, on the Jefferson High School Remodel project, to stabilize soils and lift slabs in nine classrooms, a hallway, and a bathroom.  The work included cutting L-shapes  in carpet as required for injection holes, drilling of holes, testing, injection to stabilize soil & fill voids, grouting injection holes, and re-gluing carpet and replacement of any damaged tiles caused by drilling.

The work was scheduled to allow approximately 10 days to complete.

By lifting one of the classroom slabs back to original, it also realigned the cabinets along a wall   in one of the classrooms which is one  added benefit we commonly see when doing this type of  repair:  doors open and shut properly, cracks in walls close up, shelving becomes level again, etc.

The project was completed in four days vs. the ten day window for the work.  The stabilization work was completed with minimal disturbance to the facility, in half of the allotted time and under budget!  A major advantage of the CST technologies is the non-invasive and fast, clean nature of the processes. Schools, Hospitals, Shopping Centers, and other Public Use buildings are typically repaired and put immediately back into use in a matter of days vs. weeks or months.  This makes an ideal solution for projects needing to be completed over Holiday and Summer breaks or during off hours with no loss of use.

Distribution Warehouse, Slab Stabilization and Joint Fill – Pueblo, CO

A large retailer distribution center, a 1,270,000 square feet warehouse and storage facility located in Pueblo Colorado, underwent a large renovation and rehabilitation project in September of 2015. The building was acquired in 1986 and has had several additions to the original warehouse area.

The Problem

In July of 2015 a site survey revealed a large array of structural deficiencies including drainage issues, spalling issues of interi- or concrete surfaces, water infiltration, settlement of concrete floor slabs, building movement, problems with doors not shutting, cracking in the precast wall panels above bay doors, and joint filler deterioration. Roche Constructors, a highly reputable Commercial Contractor located in Greeley Colorado was awarded the contract to coordinate and provide rehabilitation of the building. CST partnered with Roche to perform the slab lifting, soil stabilization, structural repair and joint filler portions of work.

Settlement of close to 6,000 square feet of floor slab had created a bird bath in the main north/south runway at the east side of the building near the busiest loading dock bays. This area is continually pounded by loaded forklifts carrying product to and from storage areas. Soil testing determined a weak soil zone 10 to 12 feet below the slab in this area that likely contributed to the settlement. The joint sealant in the control joints in a large portion of the floor slabs had lost cohesion and needed to be replaced as well.

15 areas in the precast walls located above the large overhead dock doors had developed cracks due to impacts from large semis unloading freight.

Factors for Consideration

There were many factors CST had to consider while planning and executing the stabilization and repairs of the distribution center. Roughly 25% of the floor area that needed lifting was in the main runway. Injection hoses would need to be run along this area, but not interfere with forklift traffic. Due to the approaching holiday season, the warehouse was receiving more inventory than usual and areas had to be accessible for unloading and storing freight. Because of increased shipments and need for access to the additional storage areas, the work window was reduced to accommodate receiving personnel and provide access to the additional storage areas of the warehouse.

The original joint fill compound used in the floor slab control joints had lost cohesion in a large portion of the slab area. In order to find the most effective and long lasting solution that wouldn’t require re-application, the product specified for sealing would need to be analyzed to ensure durability.

The sheer size of the warehouse itself posed a problem with communicating between crews and warehouse personnel. Two-way radios were issued which allowed easier communication when a question arose during repairs and attributed to a successful and smooth running project.

Method/Process Applied

The CST technologies were used to lift the warehouse floor slabs and stabilize the soils beneath the slabs. In addition, 3 columns were also stabilized and lifted to match the slab elevation. The CST process uses a high density expanding structural polymer that is injected through small probes into the soils below the concrete slabs. The polymer fills voids, increases bearing capacity of the soil, and lifts the concrete. Soils were also stabilized at depth of weakness to ensure no future settlement of the area. Careful monitoring at the surface was performed during injections to control the stabilization and lifting process with surgical accuracy. The CST soil stabilization and concrete slab lifting processes provide a permanent solution for settled concrete slabs because they treat the real problem, the underlying soils.

CST worked with the retailer’s engineering staff to determine a more effective and stronger compound than what was originally specified to ensure a more permanent adhesion and performance of the joint filler for the control joints. Areas were sectioned off and treated as to not disrupt warehouse traffic. Old material was removed from the joints, backer rod and sealer were then installed with areas marked off and allowed to cure before traffic was allowed back on the area which ensured good adhesion and strength of the treated joints.

To address the cracks in the precast walls , CST employed a composite repair system designed to provide shear and flexural strengthening to compromised and damaged buildings and infrastructure. The system uses an extremely strong carbon fiber matrix that was applied to the cracked and deteriorated areas of the precast walls. The repair system is significantly faster and less expensive than traditional repairs or replacement. Interior and exterior repairs were made to strengthen and protect the precast walls from further deterioration.

Result

The entire 6,000 SF slab area was lifted back to near original elevation and columns were stabilized and lifted to align with stabilized floor slabs, control joints were treated and filled and cracks in the precast walls were repaired in the time frame required. Soils beneath the distribution center warehouse were permanently stabilized, the concrete slabs and columns were realigned eliminating trip hazards and excessive wear and tear to equipment traveling over the areas. The structural integrity of the precast walls was restored. All processes were done with zero excavation and very little disturbance to the operations within the warehouse. Work was completed while leaving one lane open at all times to fork lift traffic. Due to the fast curing time and non-disruptive CST processes, traffic was allowed back onto the treated areas within 15 minutes following stabilization. The owner of this project and the owner’s representative, Roche Construction were very pleased with the professional, quality repairs performed by CST on the distribution center warehouse.