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 the URETEK Deep Injection (UDI) 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 URETEK UDI 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.

Culvert Annular Void Fill

Utah DOT Culvert Annular Void Fill

Objective of this project was to fill annulus between culvert and surrounding embankment. The outer pipe was rusted out at the bottom and water was leaking in between the two pipes and coming out bottom of joint. Goal was to seal leaks in an outer pipe, surrounding smaller pipe and fill voids.

Critical elements of this project were dealing with the rusted out bottom of the outer surrounding pipe. Large amounts of water needed to be pushed out and fill resultant voids to assure pipe support and stability.

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. Uretek 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!

Salt Lake City Industrial Road Restoration – UT

Patching, Diamond Grinding and Joint Resealing

Located close to downtown Salt Lake City, Industrial Road at California Avenue needed some well deserved repair. Industrial Road is a critical concrete pavement thoroughfare for industrial traffic and heavy duty trucking in the area as it is located adjacent to a major truck stop and trucker fuel depot. The majority of the concrete pavement was structurally sound but, due in part to sub-grade softening caused by surface water intrusion through the joints, the pavement exhibited differential settlement between the slabs measuring up to 1.5-inches. The combination of constant heavy truck traffic and the presence of water in the sub-grade facilitated continued erosion beneath the slabs.

Although the owner, the Salt Lake City Corporation, considered replacing all concrete slabs. They opted instead to preserve the existing concrete. After all, only 10 percent of the slabs showed cracking. The methods chosen for repair were soil foundation stabilization, slabjacking, slab replacement, stitch-in-time crack repair, dowel bar retrofit (DBR), diamond grinding and joint resealing. A total of 326 dowels were retrofitted on the 1,461 square-yard project. A series of 5/8 inch holes were drilled through the slabs to facilitate the injection of high density expansive polymers into the sub-grade soil to a depth of 3.5 feet. With the deep injection process complete, the same polymers were then injected at the slab/sub-grade interface through the same 5/8-inch holes to fill fissures and voids as well as to lift each concrete slab to match the elevation of adjacent slabs. This process minimized the differential settlement between the slabs. Additional lifting was then employed beneath the slabs to create a 1.5 percent drainage slope from the crown of the road to the curb to facilitate better drainage and safety.

This design engineer decided to test an innovative new crack stitching procedure utilizing polyurethane material and fiberglass panels. The Uretek Stitch-In-Time process was selected and used beneath five slabs that contained minor cracks. Following the slab stabilization and lifting operations, the Stitch-in-Time process required the placement of ½ inch fiberglass panels (stitches) within saw cuts made perpendicular to the slab crack. The cuts were then filled with clean pea gravel and an acrylic bonding material was poured into each cut. Four stitches were placed in each candidate slab.

Following the stabilization, lifting and stitching operations, the retrofit dowel bars were installed in the slabs, severely cracked slabs were removed and new concrete was placed in the necessary areas. Once the concrete was fully cured, the entire area was diamond ground to remove remaining surface defects, increase smoothness and provide a safe, high friction wearing surface. The joints between the slabs were then cleaned and resealed to prevent the intrusion of water and incompressible materials. As a final step, a sealing compound was applied to the concrete surface to provide additional protection.
Another challenge was slab cutting at the joints prior to the lifting process. The summer heat caused slab expansion, which can bind the saw blades and restrict a slab’s upward movement. To prevent this occurrence, a chisel-shaped device was inserted into the saw cut adjacent to the trapped blade and pressure was applied to spread the cut sufficiently to allow the blade to be extracted.

The project was scheduled for 90 days but was completed in a mere 62 days and was under budget. As a result of this successful project, the owner has chosen to use concrete pavement preservation on future projects within the city. The combination of using high density expansive polymers in conjunction with other concrete pavement preservation techniques including dowel bar retrofit and diamond grinding should extend the life of this pavement for approximately 15-20 years.
According to Mike Kendell of SLC Engineering, “Ride quality was greatly improved and Salt Lake City is satisfied with the results.”

Cereal Plant Rail Car Soil Stabilization – Ogden, UT

The Problem

Undermining and settlement of sub grade soils of railway track and load out canopy area of Cereal Food Processors, Inc. plant, Ogden Utah.

Situation

Concrete Stabilization Technologies, Inc. Field Consultant, Jonathon George was contacted by Scott Roberts of Cereal Foods, Inc. concerning settlement issues around the load out area for rail cars at the cereal processing plant located in Ogden, UT.

Settlement occurred due to a water main leak which had undermined sub grade soils around approximately 120 linear feet of railway track. The area of rail canopy is supported by five pillars. The middle of the five pillars showed the greatest amount of settlement of 1 to ½ inches while the other pillars in both directions had also experienced settlement, but to a lesser degree.

Facts for Consideration

The settled area of the Cereal Food Processor plant is in area used to load rail cars with grain. The area is used on a daily basis with empty rail cars rolling into the canopy area, being loaded with grain, and then moving the heavy load to other areas of the plant for production. This being a vital part of the plant’s production sequence, taking the tracks out of service for an extended period of time, would not only slow production, but affect the plant’s profit margin. Due to the non-invasive process and rapid curing time of URETEK geopolymers, the track was only out of service for a couple of hours.

Soil test results revealed compromised soil in the settled areas at a depth of three to four feet below the surface grade. No settlement of the tracks themselves had occurred, however, tests performed beneath the tracks did reveal soft soils. As a preventative measure against future settlement in the track area, it was recommended to the owner to treat soils beneath the rail ballast as well.

Solution

Initial soil tests were made in the areas of the canopy pillars and track sub grade. Results of the testing indicated very soft soil three to four feet down into the sub grade area. Penetrometer testing also revealed soft soil beneath the track area as well.

URETEK Deep Injection Method was used to stabilize the affected areas. Repair work began at the center of the east track. 5/8” holes were drilled and probes placed into the sub grade soils. Geopolymer was injected through the probes into the soil on five feet center and four feet below the top of the concrete/asphalt overlay. The purpose of the injections between the tracks was to fill any voids, stabilizing the weak soil, and interlocking the sub grade with the ballast, preventing future settlement.

Once the track area was completed, injections were then made beneath the spread footer of each of the five pillars to stabilize soil and prevent settlement. The two pillars with the most severe settlement were addressed first. Injections were made at depths of one, three, and five feet below the bottom of each spread footer. For the remaining three pillars, injection was made at one and three feet below the bottom of each spread footer. Close monitoring of surface movement at the surface was made during injection, and movement was detected from all injections.

Results

  • 120 Linear Feet of track area sub grade soils successfully stabilized
  • CST successfully stabilized the five supporting canopy pillars in the rail car load out area
  • CST successfully stabilized 120 linear feet of weak soil beneath the rail track area.

Benefits

Time Savings:  Repairs were completed in one day. Track was useable immediately following injection of sub grade soils.
Cost Savings:  Conservatively reduced repair costs by 50% (versus reconstruction).
Longevity:  Repairs permanently stabilized the source of the settlement – weak soils, mitigating future settlement and damage to canopy as well as rail track line through area.

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