Alchatek Blog

A critical downtown Houston pedestrian tunnel had persistent water infiltration affecting the ceiling, walls, and floor throughout the structure. The tunnel serves as vital underground infrastructure in Houston's urban core, where any significant disruption would impact pedestrian traffic and building access. Initial observations revealed widespread moisture intrusion, but the full extent of the problem remained unclear until interior finishes could be removed for proper assessment. The facility required a rapid, effective solution that would minimize downtime and restore the tunnel's watertight integrity.

Initial Assessment

Once sheetrock was removed from affected areas, engineers discovered extensive water infiltration through multiple pathways in the concrete structure. Moisture intrusion was occurring through joints, cracks, and penetrations, creating a complex leak pattern that compromised the tunnel's structural integrity and usability. Traditional repair methods would have required extensive excavation from above or complete tunnel closure for membrane installation - both prohibitively disruptive options in Houston's dense downtown corridor. The assessment revealed that targeted injection could address the root cause of infiltration without major structural modifications.

Proposed Solution

Alchatek recommended using Spetec PUR GT350, a hydrophilic polyurethane grout specifically designed for active leak sealing in underground structures. This single-component material was selected for its ability to react with water to form an expanding, flexible foam that creates a permanent, waterproof barrier. The injection approach would allow precise targeting of leak sources while maintaining tunnel accessibility throughout the repair process. The polyurethane's expansion properties would ensure complete void filling and crack sealing, even in areas with irregular geometries or active water flow.

Procedures

1. Mapped all visible leak points and moisture intrusion areas throughout the tunnel structure.
2. Drilled strategic injection ports at locations determined to intercept water infiltration pathways.
3. Injected polyurethane grout through ports using positive displacement pumps, monitoring for material refusal and leak cessation.
4. Conducted systematic injections across all identified problem areas, adjusting techniques based on local conditions.
5. Verified complete sealing through visual inspection and moisture monitoring following cure completion.

Results

The polyurethane injection process successfully eliminated water infiltration throughout the tunnel structure, restoring its watertight integrity without requiring facility closure or major structural modifications. Post-treatment inspections confirmed the complete cessation of leaks, with the tunnel remaining dry even during subsequent heavy rain events. The minimally invasive approach allowed the tunnel to remain operational throughout the repair process, avoiding costly service interruptions. For a typical tunnel section, this represents over 95% cost savings compared to traditional methods. Additionally, avoiding tunnel closure prevented an estimated $10,000 to $ 25,000 in daily economic losses due to disrupted pedestrian traffic and building access, further amplifying the financial benefits of this innovative approach.

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At a state college construction site, the ground posed a karst risk (soil dissolution where limestone rock met other layers), with potential for creating underground voids and caves. Subsurface exploration confirmed void potential and loose soils needing treatment before foundations. Geotech professionals from Helicon were called in for this project.

Initial Assessment

Investigations indicated problematic overburden and voiding at depth. Adding helical piers as a deep foundation solution would extend the schedule by months and inflate costs versus grouting.

Proposed Solution

The contractor selected AP Fill 720 for hydro‑insensitivity, fast adjustable set, and NSF certification to permeate, seal, and lock soils with minimal disruption.

Procedures

• Install 141 grout injection points to depths of 23–100 ft via rotary wash drilling (rotating bit with flushing fluid to clear boreholes).
• Inject AP Fill 720 at maximum depth, raising the pipe in 5-foot increments.
• Complete stabilization using 800 cubic yards of specialized grout mixture.
• Verify soil densification and void elimination throughout the building footprint.

Results

1. Zero delays; footprint stabilized pre‑build.
2. Approximately 80–95% savings vs adding helical piers.
3. Completion in weeks, not months.

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Completion in weeks, not months. 

A tunnel structure in the Mobile, Alabama area had persistent water infiltration at the interface between concrete and metal components. The leak was traced to a tight crack at the joint, allowing water to migrate into the tunnel and cause visible staining, as well as potential long-term deterioration. The client sought a solution that would seal the leak without requiring major demolition or extended tunnel closure.

Initial Assessment

Visual inspection and on-site review identified the leak path at the interface between the concrete and metal. The crack width was measured between 0.2 and 0.3 mm, indicating that traditional cementitious grouts or surface sealants would not be effective. The challenge was to deliver a material that could penetrate deep into the joint and expand to form a watertight seal, even in confined spaces and around embedded metal.

Proposed Solution

Alchatek recommended Spetec PUR F400, a low-viscosity, hydrophobic polyurethane grout. Its ability to penetrate narrow cracks and react with water creates a durable, flexible seal. The product’s flow characteristics made it ideal for tight joints, and its expansive properties ensured comprehensive coverage within the voids and cracks. The injection plan called for drilling at the locations marked on the provided site photos, angling back toward the metal at approximately 18 inches deep to intersect the leak path.

Procedures

1. Identified injection points along the crack, using red-dot markings on the structure as a guide.
2. Drilled holes at 45° angle 12-inches apart, reaching approximately 18 inches deep to intersect the metal interface.
3. Injected Spetec PUR F400 polyurethane grout through the drilled ports, using a pump setup suitable for low-viscosity materials.
4. Monitored for material refusal and evidence of grout migration to ensure the joint was fully saturated and sealed.
5. Continued injection until the crack would not accept additional material, confirming a complete watertight barrier.

Results

The injection process successfully sealed the tunnel leak at the concrete-to-metal interface. The approach allowed for precise targeting of the leak path, with minimal disturbance to the tunnel structure and no need for extended closure or demolition. The client was able to resolve the water infiltration efficiently, reducing the risk of future deterioration and avoiding the significantly higher costs and downtime associated with traditional excavation or membrane replacement. This project demonstrates the effectiveness of modern polyurethane injection in addressing challenging below-grade leak scenarios, particularly where access is limited and the leak path is confined.

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In the realm of leak seal solutions, selecting the right equipment is crucial for the effective application of grouts. The SealMaster gun, developed by Alchatek, is designed specifically for crack injection and curtain grouting tasks. This tool facilitates controlled delivery of materials into cracks and voids, ensuring thorough penetration and sealing in concrete structures. Ideal for professionals in advanced leak seal operations, the SealMaster gun combines functionality with user-friendly features to support an efficient workflow on-site.

Features

• Built-in pressure gauge.
• Extended whip hose.
• Simple design.

Benefits

• Monitor back pressure.
• Low maintenance.
• Easy port connection and disconnection.

The SealMaster adjustable flow gun stands out as a reliable choice for contractors focused on leak seal applications, offering simplicity and precision that minimize downtime and enhance project outcomes.

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After the removal of a wooden deck, dangerous voids under the brick pavers were revealed in a luxury apartment pool deck, threatening its integrity and safety. The property owner contacted Helicon, a trusted foundation repair company.

Initial Assessment

Subsurface investigation confirmed extensive voiding with no practical access for excavation during occupancy. Demolition/replacement would take weeks, cost tens of thousands, and the pool would need to be closed during peak season.

Proposed Solution

The contractor selected AP Lift 440 for its hydro‑insensitivity, ~15‑minute cure, and ~80 psi compressive strength. This material was ideal for increasing the soil's bearing capacity and restoring the pool to its correct state.

Procedures

1. Map the void locations using ground-penetrating radar and probing.
2. Establish an injection grid targeting the largest voids first.
3. Drill strategic injection ports through pavers to void spaces.
4. Inject AP Lift 440 to refusal using calibrated pressure monitoring.
5. Allow 15-minute cure
6. Seal injection ports and restore surface aesthetics.

Results

• Structural integrity fully restored with 1,200 lbs of AP Lift 440, filling all voids.
• Zero operational downtime; pool deck remained accessible throughout repair.
• Approximately 70-90% cost savings compared to demolition/replacement alternatives.

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A Tennessee state correctional facility had a significant infrastructure failure when newly installed plumbing beneath a concrete slab malfunctioned. In an attempt to address the issue, the original contractor backfilled the entire plumbing system with concrete. When this approach proved unsuccessful, a second contractor was brought in to demolish the concrete and properly repair the plumbing systems. This process left a substantial void beneath the slab that required immediate filling to restore structural integrity and minimize facility downtime.

Initial Assessment

Following the plumbing repairs, engineers assessed a void measuring approximately 200 square feet in area and 4-5 feet in depth, totaling roughly 800-1,000 cubic feet of empty space beneath the concrete slab. The prison's security restrictions severely limited access to equipment, making traditional concrete replacement a challenging and time-consuming process. The facility required a solution that would minimize disruption to operations while providing structural support equivalent to the original concrete base.

Proposed Solution

Working with Alchatek, Mid-South Concrete Lifting recommended using  AP Fill 420, a two-component structural polyurethane foam, to fill the substantial void. This approach offered several critical advantages for the correctional facility environment. The material could be applied through a simple hose system, eliminating the need for heavy concrete trucks and mixing equipment that would be difficult to maneuver through security checkpoints. The foam's rapid curing time would significantly reduce the project timeline, and its structural properties would provide adequate load-bearing capacity for the slab above.

Procedures

1. Security clearance and equipment inspection were completed to bring polyurethane application equipment into the facility.
2. The void was accessed through existing openings created during the concrete removal process.
3. AP Fill 420 was applied using a free-shooting technique.
4. Material application was monitored to ensure complete filling and proper expansion throughout the space.

Results

The void filling was completed in 3 hours versus an estimated week for concrete replacement. AP Fill 420 polyurethane foam successfully filled the entire void space and provided adequate structural support. Prison officials expressed satisfaction with the efficiency and minimal operational disruption, leading the contractor to look at another similar project at a different state facility.

The polyurethane approach delivered 65-75% cost savings compared to traditional concrete replacement when accounting for materials, equipment, labor, and reduced facility disruption. The accelerated timeline also eliminated the extended security coordination costs typically associated with longer construction projects.

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Alchatek has streamlined its two-component production system according to lean manufacturing guidelines. These investments will ensure timely delivery of the high-quality products our customers depend on for their geotechnical projects.

• Material Handling System Automation: Our improved system speeds up material production while keeping quality levels high, ensuring a consistent supply of finished products to meet growing customer demand.
• Streamlined Filling Process: By redesigning workflows to minimize non-value-added activities, we’ve simplified operations, reducing cycle time and boosting team productivity. This translates to faster delivery and greater reliability for customers.
• Real-Time Process Monitoring: Advanced sensors provide continuous feedback on bulk tank material levels, enabling just-in-time inventory management. This keeps our production agile, ensuring customers get the products they need without delays.

These lean-driven investments reflect Alchatek’s dedication to customer satisfaction. By focusing on value stream optimization, we’re better equipped to deliver reliable, high-quality solutions to support your geotechnical projects efficiently and effectively.

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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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In the fast-paced world of geotechnical contracting, having a team member who truly understands the grind of the field can make all the difference. That's why we're thrilled to introduce Antwon Butts, our newest Tech Support Technician on the Technical Services team. With a career built on the front lines, Antwon steps into this role ready to bridge the gap between product innovation and real-world application, helping contractors like you tackle everything from soil stabilization to complex grouting challenges with confidence.

Antwon's journey in the industry is a testament to his dedication and versatility. He most recently served as Production Manager here at Alchatek, where he honed his skills in manufacturing and quality control for polyurethane-based solutions—ensuring every batch meets the high standards demanded by demanding jobsites. Prior to that, as Lead Technician at Ground Consolidation Services, he led on-site operations for soil consolidation and injection projects, managing teams through high-stakes scenarios that required quick thinking and precise execution. Over more than a decade, these roles have equipped him with a deep well of practical knowledge, from equipment troubleshooting to optimizing workflows under pressure.

What sets Antwon apart is his ability to translate that hard-earned experience into actionable support for you. Whether you're dealing with void filling, concrete lifting, or emergency repairs, his expertise in a broad spectrum of tools, products, and techniques means faster resolutions and fewer headaches. As any seasoned contractor will tell you, field proficiency isn't just valuable—it's irreplaceable. With Antwon on board, our Technical Services team is even better positioned to be your go-to partner, turning potential pitfalls into seamless successes.

Antwon can be reached via phone at 470-925-1303.

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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.

Want more information on lifting slabs with polyurethane?