Alchatek Blog

An old farmhouse with a wrap-around porch in Lake Orion, Michigan, presented a unique challenge. Beneath the porch lay an old cellar, initially used for coal storage but now serving only as a conduit for a well line into the residence. The primary concern was the inward buckling of the cellar walls, which posed a significant safety hazard. Many contractors suggested demolishing the porch and excavating the cellar, a solution that would have incurred substantial costs for both demolition and reconstruction.

Initial Assessment

Suburban Basement was engaged to address this issue. Upon evaluation, the team identified a more cost-effective and less invasive solution. The cellar, measuring 12 feet in length, 5 feet in height, and 5 feet in width, could be filled with foam to mitigate the risk of further wall collapse. This approach would spare the property owner the expensive and disruptive process of demolition and reconstruction.

Proposed Solution

The team proposed filling the cellar with Alchatek’s AP Lift 430 foam. This material was chosen for its extensive expansion rate, superior compressive strength, and lower application temperatures. These properties allowed for quicker application intervals while maintaining optimal temperatures between applications and minimizing ignition risks.

Procedures

1. Encapsulated the well line with sonotubes elevated above the cellar floor, ensuring future accessibility.
2. Installed OSB sheathing to define foam boundaries and prevent overflow.
3. Applied AP Lift 430 in layers, allowing cooling intervals between applications to optimize expansion and stability.
4. Coordinated with masons to prepare for CMU block installation at the containment boundary, ensuring seamless alignment with the existing foundation.

Results

The foam-filling solution successfully stabilized the cellar walls, eliminating the collapse risk while preserving functionality. Compared to traditional approaches, this method saved the client approximately $25,000 and maintained the home’s historic features. Completed in just five days, the project significantly outpaced conventional methods. Homeowners were highly satisfied with the noninvasive approach, cost savings, and seamless integration with their property’s historic character, demonstrating the effectiveness of innovative techniques in addressing complex structural challenges in historic properties.

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Suburban Basement was contracted to address a multifaceted water intrusion issue on a Rochester Hills, Michigan property. The basement had water ingress from both the furnace ductwork and the foundation. The ductwork, extending through the foundation wall into a garage-adjacent wall cavity, had sections below grade behind a garage curb. The root of the problem was water pooling under the back curb, caused by settled garage slabs from the main vehicle entrance.

Initial Assessment

The project was divided into two phases: first, addressing the leaking foundation and furnace ductwork, and second, void filling and concrete leveling of the garage floor and curb. The complexity arose from the undermined garage slabs and the need to prevent water intrusion while ensuring the safety of the furnace ductwork.

Proposed Solution

For the initial water intrusion, Suburban Basement proposed using Alchatek’s Spetec PUR Highfoamer for curtain grouting, given the limited accessibility and its fast reaction time. For the concrete leveling and void filling, AP Lift 430 was selected due to its expansion rate, soil stabilization capabilities, water displacement properties, and quick curing time for vehicle traffic.

Procedures

1. Applied curtain grout to the positive side of the wall to stop water intrusion and encapsulate the dual wall furnace ductwork
2. Commenced void filling and leveling at the garage curb, progressing toward the main vehicle entrance
3. Filled all voids beneath the garage curb and leveled the concrete across all areas of concern
4. Conducted water tests to ensure all leaks were addressed before proceeding to phase two
5. Performed void filling and concrete leveling, displacing significant amounts of water near the main vehicle entrance

Results

The project was completed successfully in two phases, with the curtain grouting finished within hours and the void filling and concrete leveling taking approximately half a day. All leaks were effectively stopped, and the concrete was successfully leveled. The homeowner expressed high satisfaction, notably as previous repair attempts had failed. Suburban Basement’s solution not only resolved the immediate water intrusion problems but also extended the lifespan of the garage concrete and driveway, providing a comprehensive fix to a complex issue.

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Management at a luxury hotel in Atlanta contacted geotech specialists Panhandle Seawall and Infrastructure after discovering significant voids beneath their swimming pool during routine maintenance. What began as a standard pool inspection quickly escalated into a serious structural emergency that threatened the integrity of part of the building. PSI was able to mobilize within days, providing temporary support until the foundation contractor could underpin the column footing and provide a permanent solution.

Initial Assessment

The investigation began when hotel maintenance staff noticed several concerning issues:

• Visible cracks developing in the pool structure.
• Accelerated water loss beyond normal evaporation.
• Significant increase in monthly water bills.
• Further investigation revealed an approximately 800 cubic foot void beneath the pool.
• A critical structural issue where a column footing was precariously supported only by the edge of a rock formation.

The severity of the situation led to a partial condemnation of the hotel structure, requiring immediate intervention to prevent potential catastrophic failure.

Proposed Solution

After careful evaluation by the project engineers, AP Lift 475 was selected as the optimal solution due to its superior characteristics:

• Higher density formulation for enhanced structural support.
• Superior bearing capacity to meet engineering requirements.
• Rapid deployment capabilities for emergency situations.

The project required approximately 300 gallons of material, deployed in three separate sets, to provide the necessary structural reinforcement.

Procedures

1. Safety Implementation

• Installation of proper ventilation systems.
• Deployment of temporary support beams.
• Setup of adequate lighting for the work area.

2. Grout Implementation

• Initial deployment of the Deep Lock® method to solidify underlying soil.
• Systematic void filling through carefully timed injection intervals.
• Continuous monitoring of material flow and structural response.
• Progressive filling to ensure complete void elimination and stabilization of footing.

Results and Conclusion

• The emergency shoring proved successful on multiple fronts:
• Complete stabilization of the compromised column footing.
• Establishment of solid connectivity between the underlying soil and structural elements.
• Prevention of further structural degradation.
• Removal of condemnation threat to the building.
• Restoration of structural integrity to engineering standards.

The project demonstrated the effectiveness of polyurethane void fill as a rapid response solution for critical structural emergencies, successfully averting potential building failure while providing a long-term stabilization solution.

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The owner of a gas manufacturing facility contacted a Georgia-based contractor regarding significant floor settlement issues, with a warehouse slab dropping approximately 3-4 inches. The settlement made issues for the forklift traversing in and out of the warehouse and posed a risk to the workers.

Initial Assessment

Upon arrival at the site, the team conducted a thorough investigation. Using a probe, voids were identified beneath the slab, with the probe sinking up to 2 feet in some areas. A Dynamic Cone Penetrometer test revealed large voids 2-4 feet below the slab.  Poor drainage was evident, with improper crowning causing water to flow towards the building instead of away from it. Interestingly, a layer of unusually hard clay was noticed outside the building, suggesting possible prior remediation attempts.

Proposed Solution

AP Lift 430 was chosen for this project, providing an excellent injectable polyurethane grout solution. With its impressive 22x expansion capability and 7,200 psf compressive strength, it’s ideal for warehouse slabs that support heavy equipment. The grout’s hydrophobic properties ensure long-term stability by blocking water infiltration that could otherwise lead to void formation.

Procedures

1. Deep Injection (Void Fill)

• 32 injection points were established in a grid pattern (16 on each side) at 4 ft apart.
• At each point, the team injected 15-20 pounds of material at about 5 feet depth.
• A slight lift (approximately 1/16 inch) during this phase indicated successful void filling.

2. Slab Lifting

• Additional holes were drilled next to the wall, 3 feet from the wall, and 9 feet from the wall (6 feet from the first row).
• Injection began from the holes nearest to the wall and moved outward.
• Multiple passes were made, with some areas requiring 3-4 injections.
• Gradual lifting was employed to prevent slab cracking.
• Dial indicators were used to ensure even lifting across the warehouse floor.

Results

The project successfully stabilized the warehouse floor and restored it to its proper level. Effective void-filling addressed the underlying instability, providing a solid foundation for the slab. Success was evident in the restored functionality of the warehouse space and the elimination of safety hazards posed by the uneven floor. The property manager was pleased with the work and requested additional slab lifting services for their other facilities.

Want more information on lifting slabs with polyurethane?

Essential Details

Dates/Pricing (Discount Deadline Extended!)

Geotechnical Masterclass: March 25th - 27th, 2025

$695.00
This is special pricing for all who register before the end of the day, March 2nd. $745 March 3rd and later. ($50 discount for each additional participant.)

Location

Atlanta, GA

Discount

$50 discount for each additional participant.

Geotechnical Masterclass

Elevate your geotechnical expertise with our comprehensive masterclass covering cutting-edge techniques and solutions. Master:

• Polyurethane Concrete Leveling for sunken slabs
• Polyurethane Soil Stabilization for various soil types
• Geotechnical Testing with precision
• Deep Lock® soil stabilization procedures

Why Attend?

• Gain Hands-On Experience with state-of-the-art equipment
• Learn From Industry-Leading Experts with decades of experience
• Network with Peers and potential collaborators
• Boost Your Company’s Market Reach and capabilities

Consider the low cost of training vs. the high cost of job screw-ups and missed opportunities.

Transitioning from routine geotechnical work to more complex and high-stakes infrastructure and large-scale construction projects represents a significant growth opportunity for your career and business. Get the advanced skills and critical insights needed to tackle challenging projects and succeed in competitive markets confidently.

Join us for this transformative Geotechnical Masterclass. We’ll equip you with the knowledge and techniques to excel across all geotechnical project types.

Essential Details

Dates/Pricing

Geotechnical Masterclass: March 25th - 27th, 2025

$695.00
This is special pricing for all who register before the end of the day, February 25th. $745 February 26th and later. ($50 discount for each additional participant.)

Location

Atlanta, GA

Discount

$50 discount for each additional participant.

Geotechnical Masterclass

Elevate your geotechnical expertise with our comprehensive masterclass covering cutting-edge techniques and solutions. Master:

• Polyurethane Concrete Leveling for sunken slabs
• Polyurethane Soil Stabilization for various soil types
• Geotechnical Testing with precision
• Deep Lock® soil stabilization procedures

Why Attend?

• Gain Hands-On Experience with state-of-the-art equipment
• Learn From Industry-Leading Experts with decades of experience
• Network with Peers and potential collaborators
• Boost Your Company’s Market Reach and capabilities

Consider the low cost of training vs. the high cost of job screw-ups and missed opportunities.

Transitioning from routine geotechnical work to more complex and high-stakes infrastructure and large-scale construction projects represents a significant growth opportunity for your career and business. Get the advanced skills and critical insights needed to tackle challenging projects and succeed in competitive markets confidently.

Join us for this transformative Geotechnical Masterclass. We’ll equip you with the knowledge and techniques to excel across all geotechnical project types.

A concrete staircase in a prominent mixed-use complex in Atlanta needed urgent repairs due to a set of 75-foot-long sunken steps. This issue posed a significant trip hazard, potentially compromising visitor safety. The problem stemmed from a combination of factors working together over time. Water infiltration through expansion cracks had created voids beneath the stairs, weakening their foundation. Compounding this issue was the natural tendency of separate concrete pieces to expand and contract, moving independently. This movement was particularly problematic as it caused the steps to separate from the adjacent sidewalk. Over time, the repeated cycles of expansion and contraction, coupled with the underlying voids, led to the steps sinking and rolling, creating a hazardous situation. 

Local experts from Engineered Restorations were called in to tackle this tricky situation. The team faced the challenge of addressing safety concerns while preserving the structural integrity of the staircase.

Powerful Polymers

AP Lift 430 was selected as the repair material for this restoration project. This polyurethane foam has expansive properties that are suitable for lifting sunken structures. Once cured, AP Lift 430 provides support for long-term stability, aligning with the project's requirements.

Painless Procedures

The repair process began with an assessment of the trip hazard. This allowed the team to determine the extent of the problem and plan their approach. Next, backer rods between the steps and sidewalk were removed to prepare the area for treatment. Alchatek Surface Guard 125 was applied around the injection area to prevent any excess polyurethane from bonding to the concrete. Protective sheets were placed to shield nearby glass surfaces.

The team drilled holes through the 8-inch concrete steps to reach the underlying soil. Soil probes revealed firm underlying conditions. The team then implemented their injection strategy. They created an initial foam layer slowly, injecting it just once every ten seconds. This gradual approach prevented existing hairline cracks from expanding during the lifting process. The team continued to inject AP Fill 430 until the steps were level. Finally, they redrilled and applied a second injection layer beneath the first to fill any voids created in the process. New backer rods were then installed.

To enhance the longevity of the repair, the team took an additional crucial step. They sealed the expansion joints with silicone, creating an optimal water barrier. This silicone sealant is flexible, accommodating future expansion and contraction. This extra measure was designed to protect the structure from water infiltration and movement, addressing the root causes of the original problem. 

Rapid Results

In just four hours, the steps were restored to a level position, aligning with the adjacent walkway. This efficient repair method addressed the immediate safety issue while extending the structure's lifespan. By lifting the existing steps rather than replacing them, the property owner avoided substantial expenses associated with demolition, new materials, and extended labor time for a complete replacement. This approach ultimately provided significant cost savings.

Want more information on concrete leveling with polyurethane?

Essential Details

Dates/Pricing

Geotechnical Masterclass: March 25th - 27th, 2025

$695.00
This is special pricing for all who register before the end of day, February 25th. $745 February 26th and later. ($50 discount for each additional participant.)

Location

To Be Determined
(in Georgia)

Discount

$50 discount for each additional participant.

Geotechnical Masterclass

Elevate your geotechnical expertise with our comprehensive masterclass covering cutting-edge techniques and solutions. Master:

• Polyurethane Concrete Leveling for sunken slabs
• Polyurethane Soil Stabilization for various soil types
• Geotechnical Testing with precision
• Deep Lock® soil stabilization procedures

Why Attend?

• Gain Hands-On Experience with state-of-the-art equipment
• Learn From Industry-Leading Experts with decades of experience
• Network with Peers and potential collaborators
• Boost Your Company’s Market Reach and capabilities

Consider the low cost of training vs. the high cost of job screw-ups and missed opportunities.

Transitioning from routine geotechnical work to more complex and high-stakes infrastructure and large-scale construction projects represents a significant growth opportunity for your career and business. Get the advanced skills and critical insights needed to tackle challenging projects and succeed in competitive markets confidently.

Join us for this transformative Geotechnical Masterclass. We’ll equip you with the knowledge and techniques to excel across all geotechnical project types.

At a new solar field installation in North Florida, there were areas of bad soil where the H piles were not passing the loading and pull testing.  Solar panels lay at an angle, and if a strong wind is coming from one direction, it can try to “lift” the panel and pile.  Conversely, a strong wind coming from the opposite direction creates a downward force and can drive the supporting pile into the soil.

Powerful Polymers

The general contractor contacted the grouting specialists at Stable Soils and asked if they could use cement grout to try and lock the piles into place. Because of the tight confines between rows of piles, the specialist suggested a polyurethane permeation grout, Alchatek's AP Soil 600. The required installation equipment is more compact and it is a lot cleaner to install than cement. AP Soil 600 is moisture-activated (the same as Gorilla Glue), but it only takes about 5% moisture in the soil to make it react.  AP Soil 600 is heavier than water by design, and it is also hydrophobic.  As it soaks in, it pushes through the moisture and displaces it.  Once it cures, the sand is locked together. As the AP Soil 600 soaks into the damp sand, it reacts and produces carbon dioxide.  The CO² creates a swelling effect, driving the resin further into the sandy soil.

Painless Procedures

Around 20 test piles were installed at the solar field.  AP Soil 600 was injected right against the steel at a depth between 3 and 4 feet.  About 1/3 of the piles received 1-1/2 gallons.  Another third received 1 gallon, and the final third was injected with 3/4 of a gallon.  All of the piles passed the pull testing and compression testing.  The project was awarded, and around 4000 piles were injected in total.  It was a complete success.

Fast forward to 2022 at a massive solar field installation in Ft. Green, Florida.  Like many solar fields, it was not necessarily on the best land.  The site was a filled-in phosphate mine, so the soil was layered with bands of clay, sand, and mine tailings. Once again, there were sections of the solar field where the piles were not passing the pull testing, load testing, and lateral testing.

Polyurethane grouting was proposed but the manufacturer of the components wanted the proposed material to go through more vetting.  Primarily they wanted to know if the polyurethane grout would last for the 25-year service lifespan of the solar field.  Job histories, accelerated testing results, and chemical resistance data was provided, to their satisfaction.

For this project, the owners wanted to get engineers involved in the grouting portion of the installation.  Mathers Engineering was in charge, and they contracted Madrid Engineering to handle the soil testing. Testing showed that there were layers of clay and sand (referred to as zebra striping), so the grout was targeted in the sandy areas.  The thought was that the permeated sand would be locked in between layers of clay, thus improving both compression and pull strength. 

For this installation, the same three different volumes of AP Soil 600 were tested.  Once again, only 3/4 of a gallon was deemed sufficient to pass the testing, so that was what was used.  5000 piles were injected on this project, about 90% of them with AP Soil 600.  There were some areas of organic soils, and for those, AP Fill 700 was injected and tested successfully.  AP Fill 700 has over 30X expansion and works well at improving organic soils.  The work was completed in the Spring of 2022, and the solar field went into service.

Rapid Results

In the Fall of 2022, disaster struck Ft. Green, a location unfortunately positioned directly in the path of a Category 3 hurricane. The storm’s ferocity was evident as it swept through, leaving behind a trail of destruction in its wake. Trees were toppled, and the solar field, designed to endure winds exceeding 100 MPH, faced unprecedented damage. The wind from the hurricane’s eyewall proved too powerful, driving piles of solar panels into the ground. Despite their robust design, many panels were shredded, and a significant number of the piles suffered movement, highlighting the sheer force of nature’s fury.

Out of 5000 piles injected, only 9 showed any sign of movement.  The polyurethane grout was put to the test and passed with flying colors.  Currently, this field is going through the insurance claim process, but the testing for the repair method has already been completed.  The embedded piles were jacked back up to level and then grouted in place with AP Soil 600.  All of them passed the test; now, the field is waiting for the insurance to be worked out so the rest of the damaged piles can be glued back into place. AP Soil 600 carries the NSF / ANSI 61 rating.  It is safe for contact with potable water, and in this application, it will not leach any chemicals into the soil or groundwater.

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The owners of a college apartment complex in Georgia reached out to a local engineering firm after discovering a large void underneath the northwest end of the building. The issue was caused by stormwater collecting and flowing beneath the building's foundation. Over time, the foundation became exposed and now the grade has lowered by a foot from the original design.

Site Investigation and Initial Attempts

A dynamic cone penetrometer test revealed the soil was fragile, with two to three blow counts for the tested areas. Underpinning piles had been installed by the previous owner, but did not did not adequately stabilize the building's foundation. The shifting foundations caused the ceiling and wall in one of the top-level rooms to begin to crack and showed early signs of separation.

Proposed Solution

The engineering team recommended using injectable polyurethane grout. AP Lift 430 was selected for the job because of its high expansion of 22x and compressive strength of 7,200 psf. This polymer is also hydrophobic, which prevents water from causing further erosion of the void.

Implementation

1. Rod Placement: Injection rods were inserted horizontally into the void’s back, spaced 4 feet apart.
2. Foam Injection: Foam was injected through the rods until emerging from the exposed void area. This step ensured that the foam reached the farthest areas of the cavity.
3. Free-Shooting: The remaining exposed void was filled by direct foam application, ensuring comprehensive coverage.

Results and Conclusion

The end result was 658 gallons of expanded AP Lift 430 injected underneath the void. The polyurethane injection, combined with regrading work done in collaboration with a local engineering firm, successfully solved the issue and prevented further void formation underneath the student housing.

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