Alchatek Blog

Initial Assessment

An Atlanta real estate company faced significant challenges with their large warehouse, where uneven concrete slabs ranged from 0.5 to 2.5 inches below level. This unevenness led to foundation instability, wall cracking, and compromised usability of the facility. A local slab lifting company was contracted to perform void filling and slab lifting to restore the warehouse floor.

Proposed Solution

The technicians recommended using AP Lift 475, a two-component polyurethane foam designed for lifting and stabilizing concrete slabs. This material was selected for its high strength, controlled expansion, and ability to effectively fill voids while lifting sunken slabs to the desired elevation. The approach included using a large concrete cutting machine to clear joints, ensuring precise preparation without extensive disruption to warehouse operations.

Procedures

1. Established a grid pattern for injection points based on the extent of slab settlement on the warehouse floor.
2. Used a large concrete cutting machine to clear joints, ensuring unobstructed access for injections.
3. Drilled holes through the concrete slabs at predetermined injection points to access voids beneath.
4. Injected AP Lift 475 polyurethane foam into the drilled holes to fill voids and lift slabs, monitoring elevation in real-time to raise slabs up to 2.5 inches.
5. Performed multiple injection passes in areas with significant settlement to ensure even lifting.
6. Patched drilled holes to restore the surface integrity of the concrete slabs.

Results

The slab lifting project at the warehouse was a complete success. The application of AP Lift 475 effectively filled voids and raised all uneven slabs to a uniform level, eliminating foundation issues and wall cracking. The restored warehouse floor enhanced the facility’s functionality, enabling the real estate company to rent out the space, thereby maximizing its commercial potential.

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In this episode of Groundworks' Stability Matters podcast, host Justin Bryant sits down with Alchatek CEO Stephen Barton and VP of Sales Andy Powell in Atlanta to discuss polyurethane solutions for geotechnical and leak seal issues. Stephen shares his journey from young concrete repair worker to industry leader, while Andy recounts the story of his career pivot to polyurethane expertise. They cover Alchatek’s product evolution, significant projects, and the importance of engineer outreach - offering insights on many industry challenges and key topics.

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In the field of concrete leveling, reliable tools are essential for achieving accurate and efficient results. The MiniMaster Low-Pressure Gun, developed by Alchatek, serves as a robust component of the PolyBadger Mobile Slab Lifting System.

This system is engineered for portability and ease of use, making it suitable for both emerging contractors and established professionals engaged in slab lifting operations.

The MiniMaster Low-Pressure Gun facilitates the precise injection of polyurethane materials, supporting the stabilization and leveling of concrete surfaces with minimal setup requirements.

Features

• Metal construction.
• Safety lock.
• Compatible with standard static mixers.

Benefits

• Easy to clean and reuse.
• Prevents accidental material discharge.
• Ensures seamless integration with existing equipment.

The MiniMaster Low-Pressure Gun, when integrated with the PolyBadger Mobile Slab Lifting System, provides a dependable solution for demanding slab lifting projects. Its durable design and safety features contribute to reduced operational risks and improved efficiency.

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Overview

If you’re battling A-side crystallization or clogged gun screens or injectors, the A-Side In-Line Filter is  essential. Installed between the hose and the slab lifting gun, it filters isocyanate, the A-side material prone to crystallization from moisture or poor storage. The filter traps solid chunks, sediment, and contaminants, preventing clogs, ensuring smooth flow, and maintaining foam quality. By protecting components like the mixing chamber, it extends equipment life and reduces maintenance costs.

Purpose and Function

Filters A-side Material: 
The A-side material, isocyanate, is prone to crystallization when exposed to moisture or improper storage conditions. Crystallized particles can form solid chunks that clog hoses, nozzles, or gun components, leading to uneven application, equipment damage, or downtime.

Prevents Clogs: 
The inline filter traps these solid particles (crystallization chunks, sediment, or other contaminants) before the material reaches the slab lifting gun, ensuring smooth flow and consistent foam quality.

Extends Equipment Life:
By reducing the risk of clogs and damage to sensitive components like the mixing chamber or gun filters, the inline filter helps prolong the lifespan of the equipment and minimizes maintenance costs.

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At Antwerp Airport, a section of the runway slab had settled by 1–2 inches, creating a hazardous rocking effect that endangered aircraft landing gear and led to grounded flights. Aircraft wheels hitting the depressed area like a pothole generated dangerous jolts. Although the settlement had persisted for years, mounting operational demands finally compelled immediate action.

Initial Assessment

Initial investigations revealed voids beneath the 8-inch-thick concrete slab. Replacing the entire slab proved impractical because it would require a multi-day runway shutdown, extended project timelines, and substantially higher costs.

Proposed Solution

The contractor selected Alchatek’s AP Lift 430 polyurethane foam for its hydro-insensitivity, rapid strength development, 22x expansion ratio, and compressive strength of 7,200 psf. These properties enabled efficient lifting and stabilization with minimal downtime.

Procedures

1. Marked the slab and established 8 injection points in a grid pattern.
2. Drilled through the 8-inch slab and installed injection ports.
3. Injected 16 gallons of AP Lift 430 in staged passes.
4. Monitored elevations with dial indicators.
5. Sealed the drill holes and restored the surface.

Results

• The slab was lifted to specifications, resulting in zero differential settlement with adjacent panels.
• The project was completed in just 4 hours—over 90% faster than a full slab replacement.
• The international airport resumed its full flight schedule the same day, avoiding over $100,000 in losses from runway closures.

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A single-story office building settled over organic soils beneath its post-tensioned slab. With access restricted to the interior, a fast and clean repair was essential. Geotech experts from Helicon were called in to assess the situation.

Initial Assessment

Borings showed dense to very loose strata and differential movement under interior columns and slab zones; uniform densification and code‑level lift tolerance were required. Traditional underpinning inside an occupied shell would extend schedules and raise costs versus targeted polyurethane injection.

Proposed Solution

The contractor selected AP Lift 440 for hydro‑insensitivity, rapid reaction, and ~80 psi compressive strength. This material was ideal to permeate, densify, and lift with minimal downtime.

Procedures

1. Inject 30,000 lbs over 635 interior points per geotech layout.
2. Apply tight grid spacing, pressure/volume control, and real‑time elevation checks.
3. Coordinate QA/QC with the Engineer of Record for sign‑offs.

Results

• Restored slab support and column bearing
• Zero exterior disruption; interior‑only access.
• Approximately 97% cost savings vs interior underpinning/piering, with faster completion.

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Fifteen, two‑unit condominium buildings exhibited differential settlement and interior slab movement from loose organics and voiding, risking structural performance and livability. Continuous occupancy required a rapid, low‑disruption remediation strategy that delivered durable lift and stabilization. The job was completed by foundation repair specialists at Helicon.

Investigations confirmed loose to very loose near‑surface soils, voids at 3–8 ft below the surface, and active settlement beneath slabs and footings under service loads; full replacement was not viable due to resident displacement, extended schedules, and higher cost risk.

Proposed Solution

The experts at Helicon selected AP Lift 440 for its hydro‑insensitivity, rapid reaction, and ~80 psi compressive strength to permeate, densify, and lift with minimal downtime.

Procedures

1. Grid the interiors; mark piles, grout points, and quality control benchmarks.
2. Inject low‑mobility compaction grout to seal limestone and pre‑densify.
3. Install underpinning to ~36 ft, using predrill/sleeves to bypass clays.
4. Inject AP Lift 440 at 8/5/3 ft below land surface to lift slabs and encapsulate organics.
5. Monitor elevations/pressures; proof‑load and video‑verify.

Results

• Restored slab elevations and footing support with no resident displacement.
• Completion in days to weeks vs months for replacement.
• Approximately 80-90% cost savings versus full demolition/rebuild approaches.
• Durable, closed‑cell, water‑resistant stabilization for long‑term performance.

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A south Georgia roadway developed a sinkhole over a double 48-inch RCP storm line about 10 feet deep, threatening lane safety and mobility. Replacement costs were prohibitive and would require extended closure and excavation.

Initial Assessment

The pipe exhibited joint leakage and surrounding soil loss, creating voids under pavement and shoulder with settlement risk across the travel path. Traditional open-cut replacement would demand deep shoring, traffic detours, and high restoration costs, making trenchless stabilization preferable. SiteMix Pressure Grouting LLC was called in to do the work.

Proposed Solution

The contractor selected AP Lift 475 for hydrophobic chemistry, industrial strength, and rapid set to encapsulate pipe exteriors, seal soil paths, and rebuild bearing capacity with minimal downtime.

Procedures

1. Lay out three rows on 3-foot centers around both barrels.
2. Inject at 6 lb per vertical foot to refusal for soil reconsolidation.
3. Pull the injection tubing vertically while injecting to form grout columns.
4. Encapsulate/seal pipe perimeter and monitor lift response.
5. Verify surface support and closure readiness.

Results

• Completed in one day with 1,400 lbs placed; roadway lifted and voids eliminated.
• Zero excavation and minimal traffic disruption during work.
• Approximately 95% cost savings compared to pipe replacement.

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One Atlanta Plaza experienced significant settling of sidewalks and approach slabs around the perimeter of the building, creating safety hazards for pedestrians and visitors. The multi-story structure includes underground parking levels supported by piles, which remained stable, but the transition areas connecting to surrounding sidewalks were built on compacted fill. Over time, differential settlement occurred between the pile-supported structure and the soil-supported approach slabs, with some areas dropping approximately half an inch. Building management had previously attempted fixes by creating concrete "ramps" at transition points, but these temporary solutions continued to deteriorate as settlement progressed.

Initial Assessment

Engineers inspected the site and identified that the compaction difference between the soil immediately adjacent to the building foundation and the surrounding area was causing uneven settlement. This resulted in cracking of curbs, trip hazards at entrance points, and visibly sagging pavement sections, particularly noticeable at the approach to the parking garage. The most affected areas showed clear separation between the stable pile-supported structures and the settling exterior slabs. Entrance points where the differential settlement created ADA (Americans with Disabilities Act) compliance issues, and potential liability for trip-and-fall incidents were of particular concern. This problem stemmed primarily from inadequate soil compaction during the original construction.

Proposed Solution

Alchatek recommended a two-phase approach to address both the underlying soil conditions and the visible settlement. First, AP Soil 600, a single-component polyurethane product designed for soil stabilization and permeation, would be injected to densify the loose soil beneath the affected slabs. Following soil treatment, two-component polyurethane foam, AP Lift 475, would be used to lift the settled concrete sections back to their proper elevation. This non-invasive approach would eliminate the need for demolition and replacement of concrete, allowing for minimal disruption to building operations while providing a long-lasting solution.

Procedures

1. Technicians established injection points in a grid pattern, spacing them approximately 3-4 feet across the affected areas.
2. Saw cuts were made at key joints to free slabs from binding against adjacent concrete, allowing for controlled lifting without creating additional stress.
3. In the initial phase, AP 600 was injected through small drilled holes to stabilize the underlying soil and prevent future settlement.
4. After the soil stabilization phase, AP 475 was injected in multiple passes, starting from the areas closest to the building and moving outward.
5. Elevation was carefully monitored throughout the lifting process using zip levels and dial indicators to ensure proper alignment and prevent cracking.

Results

The rehabilitation project restored proper elevations at all transition points around the building, eliminating tripping hazards and improving aesthetics and safety. The lightweight polyurethane material added minimal load to the treated areas while effectively compacting and stabilizing the underlying soil.

From a financial perspective, this approach delivered significant cost savings compared to traditional repair methods. Concrete replacement would have required demolition, disposal, and new concrete installation, which is why the two-phased remediation project resulted in a 90% reduced cost compared to traditional replacement methods.

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Initial Assessment

The team at PURLevel was contacted regarding significant floor settlement issues at Outpost Harley-Davidson in Pueblo, Colorado, where a water pipe rupture had resulted in concrete movement and void spaces beneath the floor. The affected areas showed uneven surfaces with depressions ranging from 0.25 to 3 inches, creating hazards for both foot and equipment traffic.

Proposed Solution

AP Lift 430 polyurethane foam was selected for this project due to its excellent void-filling and lifting capabilities. With its 22x expansion capability and 7,200 psf compressive strength, this material is ideal for commercial floors supporting heavy equipment like that found in a motorcycle dealership.

Procedures

1. Site Preparation

   • The affected area was thoroughly inspected to determine the full extent of damage.
   • A 5'x5' grid pattern was marked across the entire interior floor area.

2. Grid Injection

   • Strategically placed injection points were established following the grid pattern.
   • Holes were drilled through the concrete slab at each injection point.
   • Polyurethane foam was systematically injected to fill voids beneath the slab.

3. Lift and Stabilization

   • After initial void filling, additional injections were performed to lift the sunken areas gradually.
   • An incremental lifting approach was used to prevent concrete cracking.
   • Areas requiring significant lift (up to 3 inches) received multiple injection passes.
   • Levels were continuously monitored to ensure even lifting across the floor surface.

Results

The project successfully stabilized the Outpost Harley-Davidson floor and restored it to its proper level. The comprehensive void-filling addressed the underlying instability caused by the water pipe rupture, providing a solid foundation for the concrete slab. Success was evident in the restored functionality of the dealership floor and the elimination of safety hazards posed by the uneven surface.

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