Alchatek Blog

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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A broadband provider in Alpharetta, Georgia, contacted a local leak seal contractor after discovering water infiltration through a crawl space wall during heavy rainstorms. Over time, cracks had developed, allowing not only water but also sediment to enter, creating substantial voids outside the fissures upon inspection. Given the sensitivity and high value of the equipment housed within the facility, eliminating all potential leaks in the crawl space became a top priority.

Powerful Polymers

The technicians chose Alchatek’s Spetec PUR HighFoamer to address this leak. This highly expansive polyurethane grout creates a robust, waterproof barrier, effectively sealing a wide variety of leaks without extensive excavation. Spetec PUR HighFoamer’s remarkable expansion capacity (40x-50x) ensures comprehensive coverage and a tight seal, making it ideal for projects requiring minimal downtime. Its NSF 61 certification guarantees safety for potable water applications, positioning this product as a versatile and cost-effective choice for leak sealing projects across various industries.

Painless Procedures

The repair process consisted of three efficient steps. First, the crew drilled through the concrete wall, installing zerk fittings into each hole for subsequent injections. Next, they used an electric airless sprayer to inject water into each fitting, ensuring proper activation of the foam. Finally, they injected Spetec PUR HighFoamer through these fittings. This created a curtain wall of polyurethane foam that effectively sealed the cracks, prevented further water ingress, and filled voids in the soil substrate.

Rapid Results

Within 24 hours, the technicians successfully sealed all leaks in the underlying crawl space. This injection process was completed in a fraction of the time required for a full membrane replacement. Months after the repair, following several heavy rainstorms, the facility manager confirmed that the crawl space has remained completely dry, with no recurrence of leaks.

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