Crescent Electric Supply – Gillette, WY

Structure Characteristics: The building is a single story structure approximately 80 feet by 125 feet in size and consists of wood post and beam framing, such as a pole building. The walls are constructed of wood posts, embedded in concrete piers at approximately 8 feet on center. The posts provide the vertical and lateral support for the walls and roof. The roof is framed with preengineered wood roof trusses. The floor of the building consists of a 6 inch thick reinforced concrete slab on grade. A septic tank and a leach field are situated along the west side of the building.

Problems That Prompted Repair: The building and concrete slab on grade were experiencing settlement. The settlement had caused cracks in the concrete slab on grade and interior finishes of the office area of the building. The majority of settlement occurred along the west side of the building and the concrete slab on grade in the warehouse were cracked the entire length of the building. Cracking ranged 3 to 8 feet east of the west wall. A slab construction joint existing in the center of the building and spans north/south. The joint appeared to have separated as a result of the slab settlement along the building.

Inspection/Evaluation Methods: A structural Observation and Geotechnical Soil Study were performed. Field investigation also performed with the use of a Dynamic Cone Penetrometer (DCP). The primary purpose of this tool is to locate the weak zones in the soils and quantify the comparative degree of ground densification improvement achieved by the deep injection process, as exhibited by the increased number of percussive blows required to penetrate the treated soil mass, when compared to a pre-injection test performed within the confines of the treated mass.

Test Results: The geotechnical study and structural observation indicated that the soils underlying the foundation and concrete slab on grade consisted of soft clays with considerably high moisture content. These soils are notorious for settlement and collapse upon wetting. It was determined that the settlement had high potential to continue if the problem was not addressed. Separation of the slab joint was determined to have been caused by the settlement of underlying soils. DCP Test results indicated weak soils at depths of 7 feet.

Causes of Deterioration: Deterioration was caused by a leak from a collapsed water tank in 2008 west of the building, effluent from the septic system, surface runoff, or a combination of these influences. Soft clay soils surrounding and beneath the structure and slab contributed to the settlement and associated damaged slab and interior finishes of the building.

Repair System Selection: Selection of the repair system was based on recommendations resulting from structural evaluation of the building. Due to the soil conditions and probability of future settlement, “Deep Injection”, using expanding structural Geo-Polymer, was chosen for correcting the settlement issues.
Site Preparation: Penetrometer testing was performed and reviewed. Mapping of the warehouse floor was completed. Profiles for settlement and finish target elevations were performed.

Demolition Method: No demolition of the existing concrete slab on grade was necessary due to
the utilization of the “internationally patented Geo-polymer injection system”. All soil remediation work was completed “In Situ”.

Surface Preparation: Surface preparation of the slab, and soil surrounding the outer perimeter of the building, prior to injecting was unnecessary. This is due to the unique nature of the expanding Geo-Polymer technology utilized. Minimal cleanup of the joint area was performed before epoxy was injected and caulking repairs were performed in the west joints and wide joint in the center of the warehouse. The crack repair and joint sealing was performed in the floor slab. Cracks were mechanically routed and gravity fed structural epoxy was injected into the cracks. Caulking of the joints was completed using a urethane sealant as specified by the engineer. Approximately 136 linear feet of cracks and approximately 124 linear feet of control joints were primed and caulked.

Application Method Selection: Repairs required utilization of a specialty technique. The foundation type (posts embedded in shallow concrete piers) does not lend itself well to helical pier stabilization. Stabilization of the underlying soils, individual concrete piers, and the concrete slab on grade itself needed to be modified in order to arrest future settlement. Therefore, the best method of application and method of repair was determined to be the injection of expanding structural Geo-Polymer.

Repair Process Execution: Initial testing of the soils were performed and analyzed to determine injection depths necessary to stabilize the underlying soil structure. Areas to be addressed were mapped and injection ports were prepared beforehand to accommodate frozen soil conditions at the time of repair. The injection of the patented Geo-Polymer material was used to penetrate deeply into the sub grade at depths of an estimated seven feet. Voids beneath the slabs were filled, and slabs lifted back to original elevations. Sub grade soils were stabilized using this Internationally Patented Technology. Deep Injection permanently altered the soil structure, thus stabilizing and preventing future settlement. Once soils were treated, the slab joints were sealed and caulked with epoxy as specified by the project engineer.

Structural floor repair: Sub contractor, gravity fed low viscosity epoxy into the floor cracks to re- establish the original monolithic strength.
Control joint sealants: Sub contractor mechanically cleaned the sides of the existing control joint and caulked with urethane primer and sealant.

Unforeseen Conditions Found: The work was performed in January which added concern for frozen ground and cold temperatures. The settlement originated below frost line. The Project Superintendent made additional efforts to keep equipment warm. The exothermic reaction of the Geo-polymer materials provided further protection against frozen conditions.

It was decided to perform the work on the client’s preferred schedule if possible. One of the unique characteristics of the Geo-Polymer is that it will not freeze during injections (it is not a water based material). Since unit weight was minimized and polymer did not add burden to weakened sub- grade, frozen ground and cold temps did not interfere with the work schedule.

Special Features and benefits of Geo-Polymer Deep Injection Repair Process:

  • Eliminated cause of settlement and future potential settlement resulting from the water spill.
  • Raised building and slabs to original elevation.
  • Saved concrete slab, and interior finish from further damage.
  • No downtime to business, timely, safe, clean.
  • All work done from above ground without excavation, In-Situ.
  • The Business was able to remain fully open during repairs with very little disruption to activities.
  • Floor sub-grade was restored to give full support for heavy forklift traffic.
  • Structural repair of floors was completed with full co-ordination of warehouse use.
  • Project was completed using permanent and economical, “Deep Injection” of Geo-Polymer.

Battle Mountain Highway Frost Heave – Encampment, WY

Abstract

This project investigated a novel procedure to reduce or prevent subgrade freezing non-destructively by injecting a two part rigid polymer foam at the top of the subgrade. Controlled injection of a CST expanding structural polymer foam created a continuous three inch thick layer of insulation that significantly reduced the heat loss from the deeper soil and prevented the upward movement of water from the warmer regime under the foam to the upper frozen regime above the foam, preventing segregational freezing in the upper zone. The construction time for the 170 foot section was one week for injection and milling the surface. Construction was contained in one lane, leaving a lane open for the entire duration without a detour, increasing safety and minimizing impact for the driving public.

Additionally, a procedure is developed for estimating the thickness of the foam layer required for other sites with different average temperatures.

Objectives

  • Can foam be injected nondestructively to level the road surface and make the road safer to drive without full reconstruction?
  • Will the foam layer provide a sufficient thermal barrier to prevent heat loss and reduce frost heave?
  • Will a continuous layer of foam create a barrier to vertical water movement and reduce spring thaw degradation?

Background

  • This section of Highway WY-70 was constructed in the early 1980’s. The highway crosses a crystalline caprock ridge outcrop that the contractor had difficulty removing.
  • The contractor was allowed to alter the design to leave the ridge intact and place three feet of compacted silty sand fill over the rock with the sub-base and base course on top over a distance of 150 feet.
  • Lateral drains and cross drains have not completely removed the water under the pavement. .
  • The combination of a frost susceptible silty sand, extended cold temperatures and the availability of water provide the necessary pieces for segregational frost heave.
  • Measured heaves of three inches and reported heaves of four to six inches created a dangerous bump over a short distance of 75 feet. In addition, a drain installed over the caprock was backfilled with non-heaving backfill which created a dip significant enough to flip snowmobiles off of trailers when traveling faster than the posted speed.

Proposed Solution

A standard technique to control frost heave is to place several layers of foam insulation panels below the sub-base course. This requires a full reconstruction of the site. A process was proposed to inject a three inch thick layer of a two part structural polymer foam at the bottom of the sub-base without removing the existing road surface.

Construction

Concrete Stabilization Technologies, Inc (CST) injected the foam through a series of 3/4 inch diameter, 18 inch deep holes drilled through the road surface on a 6 foot grid. Three inches of foam were injected over the area with the most heave. Additional injections provided tapered zones to smooth the transition from the original road surface to the full thickness zone.

The process required two trucks and a four person crew to complete the work in four days. All the work was performed in one traffic lane at a time while keeping the other lane open for traffic. Because of the poor road surface before the injection, the surface was milled at a later time. The subsequent road surface was sufficiently leveled to make the mediation unnoticeable.

Injection and Instrumentation Locations

  • Thirty survey points at 10 feet centers were measured over a 300 foot distance on five rows located at:
    • The centerline of the road,
    • The centers of the two lanes, and
    • The north and south edges of the lanes.
  • Five piezometers located in the north and south shoulders of the road.
  • Six boreholes with thermistors to measure the temperatures in the soil profile. One thermistor in each hole was located:
    • Above the injection point and the foam layer,
    • Below the foam layer, and
    • Ten inches below the foam.
    • One or two other thermistors were located lower depending on the depth to bedrock.

Results

The upper figure shows the measured elevation changes from the summer baseline along the center of the east bound lane.

    • The thin solid black line shows the heave in January prior to the injection of the foam. The dip at STA 2+10 is the location of a French drain that was backfilled with non-heaving sand.

 

    • The heavy black line shows the foam thickness averaging 3 inches with tapered edges to the east (STA 2+40 to 2+70) and west (STA 1+70 to 1+40).

 

    • The colored lines show the elevation differences in the two winters after injection. The total heave over the treated zone is generally less than 0.5 inches and is less than the natural heave outside the treated zone. The lower figure

 

    • shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

 

 

The upper figure shows the measured elevation changes from the summer baseline along the center of the east bound lane.

  • The thin solid black line shows the heave in January prior to the injection of the foam. The dip at STA 2+10 is the location of a French drain that was backfilled with non-heaving sand.
  • The heavy black line shows the foam thickness averaging 3 inches with tapered edges to the east (STA 2+40 to 2+70) and west (STA 1+70 to 1+40).
  • The colored lines show the elevation differences in the two winters after injection. The total heave over the treated zone is generally less than 0.5 inches and is less than the natural heave outside the treated zone. The lower figure
  • shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

The lower figure shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

This figure shows the elevation changes along the centerline of the west bound lane. Substantial heave is shown where the foam thickness is only 1.0 to 1.5 inches.

The heavy black line in the below graph shows the thickness of the foam being about 3 inches under the east bound lane and tapering to zero under the west bound lane.

  • The thin colored line is the measured heave in the year before construction.
  • The other colored lines are the measured heaves during the two winters after construction.
  • The heave on the south edge (-12 feet) is caused by edge effects and local freezing.
The heavy black line in this graph shows the thickness of the foam being about 3 inches under the east bound lane and tapering to zero under the west bound lane. The thin colored line is the measured heave in the year before construction. The other colored lines are the measured heaves during the two winters after construction. The heave on the south edge (-12 feet) is caused by edge effects and local freezing.

Conclusions

  • Transferability of the control strategy is possible if the weather conditions in the new corridor are similar (i.e. defined by the same weather variables) to the corridor where the control strategy was developed.
  • It would be beneficial to train the decision trees with the storm data collected at the new corridor.
  • The system should be monitored till it is recommending desirable speed limits based on real time weather and traffic information.
  • From the simulation results it is observed that proposed control strategy is performing slightly better than WYDOT’s manual protocol.
  • If the control strategy is to transfer a completely new corridor, it would be ideal to collect some storm data and train the decision trees before using the control strategy in real time.

Marriott’s Mountainside Resort – Park City, UT

The Mountainside Marriott is a luxury winter ski and summertime vacation resort, nestled in the Wasatch Mountains, in Park City Utah. Park City is a beautiful historic Utah town located about half an hour east of Salt Lake City. Early pioneers and settlers traveled through this region on the Mormon Trail, and in the early 1880’s large beds of precious metals were discovered in the area and the mining boom began. Much of the area’s soil has been affected by early silver mining activity and much of the Mountainside Marriott resort had been built on old mine tailings.

Concrete Stabilization Technologies, Inc. was contacted by the Park City Mountainside Marriott’s Chief Engineer, Dave Martin in November of 2013 concerning the resort’s pool and hot tub area that had suffered significant settlement, posing trip hazards and unsafe conditions for its many visitors. Mr. Martin and CST Field Consultant, Scott Paswaters, had known each other through a prior work relationship at the Zermatt Resort in Midway, Utah. CST had completed a similar project there in 2012.

Two site visits were made to the resort in November and the affected areas surveyed. The 68 foot concrete deck slab around the pool showed settlement of one half to one inch differential. One end of the pool itself showed settlement of approximately three inches and a notable void. The upper hot tub on the south end of the pool had a slab settlement similar to the pool, in an approximate 18 foot section.

Dynamic Cone Penetrometer testing was proposed to accurately determine soil conditions in the settled areas. An estimate for repair was given based on the findings of the DCP tests.
With the 2013 Winter Ski season gearing up, the resort decided it would be best to wait and begin repairs in the spring of 2014.

Follow up on the project was made in February of 2014 and the work was coordinated with other contractors involved in additional remodeling in the pool area. Logistics of getting to the pool area with equipment was discussed and a plan devised to access the area from the south end of the pool, leading to the plaza with a run of approximately 300 feet of injection hose into the pool area.

Heat coils in the deck slabs were located and properly marked in a grid of safe zones using a Ground Penetrating Radar (GPR) system. This helped insure that no coils would be damaged during the injection process. Once the season officially closed in March, the pool was drained during the night and crews began working bright and early the next morning.

Results from the DCP tests showed unstable soil as far as 9 feet below the pool area. Injection of approximately 7,000 pounds of a CST geopolymer was estimated to properly densify and stabilize the soil, as well as realign the overlying slabs and deck areas.

Crews began by mapping out the areas to be treated. A CST geo-polymer was then injected through a pattern of 5/8 inch holes, filling voids beneath the pool & pool stairs, and re-aligning the pool deck and hot tub slab areas. CST crews completed the project in 2 days, which kept other contractors performing projects on their work schedule with no delays. The owners and Engineers of the Mountainside Marriott were very pleased with the results of CST’s precision repairs.

Benefits:

  • Realignment of the deck slabs eliminated trip hazards.
  • No excavation required for repair work to be completed.
  • Stabilization of the underlying soil arrested future settlement in the areas.
  • Increased the longevity of the pool and surrounding deck.

The Mangy Moose Restaurant – Jackson Hole, WY

Since opening in 1967 at the base of Jackson Hole’s new ski resort, the Mangy Moose has been a prominent local landmark along Village Drive in Teton Village, Jackson Hole Wyoming. The 30,000 square foot building houses a restaurant, saloon, grocery market, and retail space. It has long been a favorite of locals and the many visitors touring throughout this area.

The owner of the Mangy Moose, Jim Terry, had contacted Nelson Engineering in Jackson, Wyoming about settlement that had occurred in the building. It was discovered, by cutting a hole through the concrete slab on the ground floor of the building, that a sewer line leak from a dish washer had softened the supporting soils of the foundation and columns. Warped wooden beams in areas of the building indicated that the leak had likely gone undetected for a number of years, causing settlement and compromising the structural integrity of the building’s foundation.
Concrete Stabilization Technologies’ Regional Engineer, Roy Mathis, was contacted by Robert Norton, P.E., of Nelson Engineering concerning the settlement issues the building was experiencing and to help design a repair option that would effectively stabilize and preserve the building’s foundation.

After review of plans and photographs, a site visit and survey were performed by Roy Mathis and Kelly Schild. Initial soil density tests were performed and analyzed. Additional concerns were raised during excavation for the sewer line repair. Cracks in the mortar and a change in slope at one of the columns indicated the pivot point of the settlement.

Two repair options and pricing were presented for mitigation to stabilize the soils and get a slight lift. One option to stabilize the soil only, and a second option to obtain a partial lift of the foundation, columns, and floor. It was desirable to obtain a maximum lift without causing additional distress to the building; a full lift was not recommended however, due to the time warped timbers, and not wanting to cause additional distress to the building. The work proposal to stabilize and perform the partial lift was accepted and work scheduled for the following week. With ski season quickly approaching and final preparations being made, it was very important to the owner that repairs be completed in a timely manner.

CST Project Superintendent Tomas Ramos, and manager David Yoder met on site on November 13th to discuss de-tails of the planned repair. Work began the same day as the crew set probes and prepared the injection layout. Extent and depth of the weakened soils were determined during drilling and probe placement. Injection depths and areas were determined to assure a permanent and long lasting solution.

Inclement weather, two feet of new snow, and minus twenty degrees halted work the following day as equip-ment would not start in the freezing temps. The crew got an early start on day three, however, and after finishing probe placement, shot an initial survey, and began injections using the CST technologies. Injections were made directly below the columns and spread footers with emphasis on the weak soil zones. Existing voids were filled, and soil stabilized as crews completed repairs. All injections were completed from the interior of the building with very little disruption to owners and management. The project was completed on time and on budget, allowing owners to complete last minute details before welcoming skiers and tourists for the 2014 winter ski season. By using the CST technologies, the long lasting repairs provided a tremendous cost savings to the owners and very little disruption to their pre-ski season preparations. Stabilization of the building’s foundation will provide for many more years of use and enjoyment of this famous local landmark.

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.