Fox Hall Apartments – Las Vegas, NV

Concrete Stabilization Technologies, Inc. was contacted by Mr. Bill Sublette P.E., Owner of Foundation Stabilization, Inc., Las Vegas, NV concerning the multi-unit Fox Hall Apartment Complex at 1600 E. University Avenue in Las Vegas. Mr. Ed Russ had contacted Mr. Sublette concerning the remediation of this property. Mr. Sublette in turn contacted Roy Mathis of CST for help in determining the best solution for repairs of the property, utilizing the advanced CST Technologies.

The complex had experienced significant distress and settlement due to the solubility of subsurface soils which had produced a significant settlement of 6.25 inches on the one corner of the building and a differential settlement of over 5 inches of the concrete floor slabs. Initially one unit of the complex was identified for repair. Two additional units were also included in the project.

Factors for Consideration

Significant distress of the property had occurred due to the solubility of the subsurface soils. Settlement differential of over 5 inches on the concrete floor slab and exterior footings had produced cavities or voids in the underlying subsurface soils. Stress on the slabs had not only produced significant cracking in the interior and exterior walls and floor slabs, but also caused problems with waste lines and exterior walkways of the units. Three options were considered for repairs. Helical Piers. Micro Piles, and CST’s deep injection process.

Solution

The foundation remediation for the Fox Hall Apartments utilized injection of CST Expanding Structural Polymer in the top 5 to 7 feet of sub grade soil beneath the exterior continuous wall footing and interior slabs. The injection of the CST ESP densified the soluble silty sands and clays in the top 5 to 7 feet of sub grade soils beneath the load bearing foundations and the result was lifting of the load bearing foundations. Additionally, areas under the distressed slab were injected with CST ESP to lift and re-level the concrete floor slabs, and densify those areas of the subgrades that had low densities and porosities (voids). The process filled the voids without adding additional weight. The ESP works to interlock soils in place, and the impervious nature of the product helps to prevent future water migration into the soils which would prevent any future extension of soil collapse.

Areas of low density beneath the slab were determined by using a dynamic field penetrometer. The process was coordinated to minimize cracking in the floor slab and to ensure that the floating foundation was not lifted off the exterior continuous wall footings interior notch.

Multiple locations and depths were injected and voids filled beneath the floor slabs. Full time observation and monitoring of the injection and lift were necessary to ensure no additional cracking of the floor slabs in the units.

Results

Three apartment units were successfully repaired with one corner of the foundation being lifted 6 1/4 inches and another corner lifted 3 1/2 inches. Voids were filled and soils stabilized beneath the concrete slabs. Slabs were realigned and lifted to original grade with minimal disturbance to tenants and landscape features. The original integrity of the uniform foundation system was maintained by utilizing CST’s technologies. Work was completed in less than a week and the owner and manager of the property was very pleased with the result.

Benefits

Time Savings: Repairs were made quickly. The non-intrusive nature of the repair process resulted in minimal disturbance to landscaping & tenants of the apartment complex.

Longevity: The integrity of the original uniform foundation system was maintained by using CST’s Technologies. The foundation lift and stabilization were made without mixing a deep foundation design with the original spread foundation. The migrating nature of CST Expanding Structural Polymer not only filled voids, but interlocked soils, helping to increase stability of sub grade soils. The impervious nature of the material will prevent future water migration into the soils & prevent extension of soil collapse.

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.

American Furniture Warehouse Slab Stabilization – Longmont, CO

Concrete Stabilization Technologies was contacted by Opus Northwest, LLC, concerning American Furniture Warehouse’s Longmont Colorado distribution location. The distribution warehouse was experiencing problems with the facility’s floor slabs. The warehouse floor slabs had deflection at the construction control joints caused by slab curl. When the edges or corners of a slab curl up, often at construction joints, it’s caused by concrete at the top of the slab shrinking or contracting faster than concrete at the bottom. Drying shrinkage is the usual cause. Water leaves the top surface of the slab faster than it leaves the bottom, creating shrinkage forces that can raise slab edges or corners.

CST used a dial gauge micrometer at the construction control joints to monitor slab deflection during load transfer from fork-lift traffic. Slab deflection was approximately 1/8” prior to slab under sealing and stabilization with CST expanding structural polymer. The uneven floor slabs were causing excessive wear and tear to the facilities forklift and loading equipment used on a daily basis in the warehouse and also creating a trip hazard for employees working in the facility. It was determined that 222 of the warehouse floor slabs, approximately 50,000 square feet of floor, would need to be stabilized.

Stabilization of the warehouse slabs began with crews mapping out, drilling, and placing 5/8 Inch injection probes through the concrete slabs.

CST polymer was injected in a pattern of every 4 feet below the slabs, filling voids, stabilizing, and providing a positive seal between the underlying soils and the concrete slabs.

Different sections of the warehouse floor area were stabilized over the course of the next eight days. Slab deflection was tested with forklift traffic after CST polymer injections. Zero movement on the dial gauge micrometer verified that the slabs were completely stabilized, thus extending the service life of the existing slab. On the five year inspection in November of 2014, no additional settlement or deflection has occurred since CST completed the stabilization of the Longmont American Furniture Ware-house in June of 2009.

Benefits of Slab Stabilization & Under Sealing using CST Expanding Structural Polymers:

  • Eliminates high costs associated with tearing out and replacing faulted concrete.
  • Provides a positive seal between underlying soils and existing concrete slabs, stabilizing and increasing the use life of the existing concrete.
  • Little to no disruption to business operations. CST polymer cures quickly, within approximately 15 minutes after injection. This allows for full use of the treated areas, immediately after repairs are completed.
  • State of the art equipment and highly trained technicians provide quick, clean, and surgically precise repairs.
  • Long lasting, environmentally safe, hydro-insensitive material has no negative impact on surrounding soils or adjacent water supplies.
  • High resistance to manufacturing chemicals and oils.
  • Puts businesses in control of repair and restoration requirements of problems associated with industrial, commercial, and residential concrete assets.

LDS Meeting House – Malta, ID

The Church of Jesus Christ of Latter Day Saints Second Ward Meeting House, located in Malta Idaho, had been foundation settlement and movement in portions of the building, resulting in ongoing damage to the structure.

In the spring of 2014, LDS structural engineer, Chris Barker contacted CST’s Utah Field Consultant, Jonathan George, concerning a repair plan for the structure.

Malta Idaho is a small community located in south central Idaho. Agriculture is one of the main industries in this area. Water being pulled from aquifers for irrigation throughout the area has lowered the water table. With change to the ground water and water table below the surface, pressure areas change and shifting of soil and rock below the surface take place. Sometimes, this occurs at depths very far below the surface.

Engineering reports indicated that settlement and shifting of the soils at a considerable depth, as suspected, were likely the cause of the extensive foundation settlement and sideways movement occurring at the LDS building.

A measuring device which had been installed on the building in early spring of 2014 showed movement of 3 millimeters over a period of 4-5 months.

CST met with the LDS maintenance personnel on site and performed investigative Dynamic Cone Penetrometer tests.

Test results determined that most of the settlement was not related to the upper 15 feet of soils, lending support to the conclusion that movement was coming from considerable depth.

After a thorough site investigation and analysis of soil tests, CST proposed to employ the CST deep injection method in order to lift and stabilize the building’s foundation both around the perimeter of the building and the load bearing footers and walls on the interior. DCP tests verified soil conditions in order to create an engineered plan to address the weaker zone of soils.

Soils directly below the foundation were dry and ideal for effectively lifting and stabilizing the structure to mitigate future movement and damage.

On May 5, 2015 CST crews arrived on site. A walkthrough was made to identify all crack openings and other damage that had been caused by the settlement and sideways movement of the building. CST’s crew members began drilling injection holes on the exterior of the building near the foundation to identify the spread footer. Probes were then placed on 4 foot centers approximately 3’ to 4’ below the spread footer. Other members of the crew began drilling and preparing interior injection holes and probes and drafting the exterior survey.

On day two, crews prepared equipment to begin injections and starting on the west exterior corner, technicians began injecting structural polymer at set locations. The foundation responded and began moving quickly. Some of the exist-ing cracks began to close at this point. Crews moved back and forth in the west corner section until a total lift of 3 ½ inches was accomplished on the exterior portion of the foundation.

On the final day, crews moved to the interior of the building and complete injections to lift the slab to target elevation.

Result: The load bearing wall was lifted, stabilized and void fill completed in the treated areas. As a result, existing cracks were closed in damaged areas. Movement of the building was greatly arrested and mitigated against further structural damage. All work was completed in three shifts.

Benefit: The CST technologies require no excavation and are performed with very little disturbance or mess. Repairs are made in days, not weeks or months. No need to vacate buildings and treated areas may be used immediately following repairs.

Liquor Warehouse Slab Lift – Cheyenne, WY

The Customer

Built in 1976 over an old creek bed, this warehouse once served as an electronics distribution center for over 20 years. It now is the sole storage and distribution hub for imported liquor in the State of Wyoming.

In 2012, the State of Wyoming purchased a warehouse that was used as an electronics distribution center for over 20 years, turning the facility into a storage hub stocking Wyoming’s liquor inventory for statewide distribution.

Shortly after the state purchased the warehouse, installation of newer, higher shelving was erected to store over $18 million worth of liquor inventory. The shelving exceeded 15 feet in height allowing additional inventory to be stored for future statewide distribution.

The Challenge

Soon after liquor inventory was stocked on the warehouse shelves, warehouse managers noticed cracks appearing and growing larger in the floor slab. The additional weight from liquor inventory combined with constant pounding and vibration from forklift traffic expedited the weakening of the sub-base and floors. Warehouse management quickly recognized the topple hazard of the uneven shelving and trip hazards created by uneven floor slabs, as a huge safety concern for employees working in the facility.

After a complete evaluation of the pre-construction and existing conditions of the warehouse, results showed 1) numerous areas of differential settlement in the slab, 2) high spots caused by poor finishing techniques, 3) unraveling joints in several locations, and 4) cracks in the concrete slab ranging from hairline to 1/4” in width.

The Solution

With the goal to improve the ride and extend the useful life of the warehouse floor, the following solutions were applied to treat 12,000 square feet of warehouse floor:

  • The CST method was used to underseal, stabilize, and realign mismatched and uneven slabs
  • Joint sealing and crack repair to protect surface
  • Grinding/smoothing high spots in rolled joints
  • Remove and replace unrepairable concrete sections

The Results

Concrete Stabilization Technologies successfully treated approximately 12,000 square feet of warehouse flooring. CST completed the undersealing, slab lifting and realignment, and overall stabilization of the entire warehouse floor in 3 ½ days.

In addition to CST injections, approximately 6,300 square feet of concrete was ground down and a special concrete hardener was applied to protect the surface from future damage.

Timely completion of the warehouse stabilization allowed this important liquor inventory distribution hub to continue operations with minimal disruption and downtime.

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.