TERRA-LOK® Single Component Polyurethane Used for Foundation Stabilization of AT&T Data Center

Summary: AT&T’s general contractor, Duffey Southeast Construction, brought in NEC Keystone, Inc. for foundation stabilization and void fill using permeation chemical grout. NEC Keystone is a Tampa-based geotechnical contractor specializing in soil stabilization and has a patented injection process for permeation grout applications.

We’ve certainly learned over the past year that cloud computing has become a vital tool that has helped keep our economy going. With the ability to work, attend classes, keep connections via video conferencing, collaborate on working documents, online shopping, etc. All in the comfort of our home, we were able to sustain our economy and stay working.  Data centers have helped feed the revolution of the mobile workforce, allowing us to have fast and reliable networks.

As you can imagine, the integrity of a data center is a high priority.  Many physical factors can compromise a data center’s operational efficiency, such as network speed, temperature, server speeds, and power. However, an atypical problem was happening at a data center in Kings Mountain, NC, the building foundation’s stability concerns.

At the AT&T Kings Mountain Data Center, a 1 million sqft facility, the maintenance staff was noticing cracking along its foundation slab and a joint that had been exposed along with one of its server rooms. The cracking appeared to be progressively worsening, and the staff suspected the presence of voids.  After its engineer and subsequent GPR scans confirmed the staff’s suspicions, AT&T began to look into stability options.

AT&T’s general contractor, Duffey Southeast Construction, brought in NEC Keystone, Inc. to address the issues using permeation chemical grout. NEC Keystone is a Tampa-based geotechnical contractor specializing in soil stabilization and has a patented injection process for permeation grout applications.

The knee wall was built above the server room’s recessed foundation slab, joining the battery room’s foundation slab above.  The server room had a floating floor that was built to meet the grade of the battery room’s foundation slab. The problem was the joint, where the knee wall and battery room foundation met, was not adequately sealed and soil loss was occurring.  Because of the soil loss, cracks were forming along the joint and in the knee wall itself and led to voids underneath the battery room’s foundation, which could lead to future foundation issues.

“After a look at the plans and several conversations with AT&T’s engineering team, we determined that two issues needed to be resolved, the sealing of the joint and cracks and re-establishing the foundation’s load back into a stabilized soil media,” stated Karla Christmann, President of NEC Keystone.

To seal the cracks and joints, NEC Keystone used a two-component epoxy system called Vertapoxy. The use of Vertapoxy was to accomplish two purposes. The first was to seal the cracks, and the second was to help restrict the permeation grout to the areas underneath the slab.

After sealing the joints, NEC Keystone injected the NCFI TERRA-LOK® 24-015 polyurethane system. The TERRA-LOK® system is a low-viscosity, single component polyurethane, specially formulated for filling voids and permeate and densify loose soils.

The polymer was injected at 32 locations were through ¾” pipes at 4’ to 6’ depths (due to soil density) along a knee wall that separated the battery room and UPS room from a computer server room.

Once injected, the TERRA-LOK® 24-015 permeated the soil and filled any void areas, including the knee wall joint and cracks.  The permeation grout penetrates various soil types, including fines. After approximately 24 hours, the polyurethane fully cures and the soil below the slabs is highly dense, and the foundation load is re-established back into the soil.

“Permeation grouting is a relatively well-known and exceptional application for soil densification and void-filling,” stated Christmann, “the difference in our patented injection approach versus the rest of the industry, is the amount of control we have in ensuring the success of the project, from the reliability of the polyurethane’s performance, to the reporting and specificity of injection and densification goals. Working with reputable companies, such as NCFI, helps us ensure that the reliability and quality of our projects will continue to be top-tier.”

The AT&T Data center project was a complete success. The knee wall and the data and UPS room foundation slabs were stabilized against future soil loss and all voids were filled. The project took a total of 2 days with 1,125 lbs of the TERRA-LOK® 24-015 injected. There were no interruptions to the data center’s operations, and the customer was completely satisfied.