Spray-Applied Waterproofing

Tennessee Tunnel Turns to Spray-Lock Concrete Protection for Rehab

Water infiltration into tunnels through the wall is a common concern for designers, constructors and owners of these facilities. A good waterproofing barrier can not only keep water out of the tunnel, but also help prolong the life of the concrete and consequently the finished facility, allowing the tunnel to perform its intended function for years to come.

One company is making it its mission to extend the life of concrete, in the tunneling industry and beyond. Spray-Lock Concrete Protection (SCP), based in Chattanooga, Tennessee, offers a range of products that can help protect and restore concrete. The company got its start in the flooring market, but is expanding its offerings to other industries. The company began in 2007, but the technology it uses dates back to the 1970s.

Brent Rollins has spent his career in the concrete industry, serving as the director of the Civil Engineering Materials Research Laboratory at the University of Tennessee at Chattanooga, before joining Spray-Lock in 2017, where he is now vice president of business development. “Our concrete is not lasting as long as it should, and as a result, our infrastructure is not standing the test of time,” he says. “It is our mission to help concrete last longer.”

The challenge, he says, is getting designers and end-users to be aware of the product and its capabilities. “Anytime you’re introducing a new technology that’s different than what has been used on previous projects, there’s a certain amount of tire-kicking that occurs,” he says. “There has to be testing and review of the data in order to get the product approved. That is a natural process that we’re going through right now. We’re confident in the ability of the product to perform as intended, so it’s just a matter of getting people to start specifying it.”

SCP uses a nano colloidal silica product which is spray-applied and gets pulled into concrete through naturally occurring capillaries where it reacts with calcium hydroxide to form calcium silica hydrate. “This equates to a more complete packing of the mix, creating a less permeable concrete that then becomes more durable,” says Bob Banka, president of Omega Concrete Solutions, a nationwide network of concrete professional franchises trained in the proper techniques to use SCP technology.

Most Spray-Lock products are spray-applied after the concrete is placed, but they also have a product, Amorfa, that can be added to the concrete as it is being added to a concrete mixer. It can be applied to shotcrete or conventionally formed concrete structures. Spray-Lock officials recommend using a low-pressure, high-volume spray system to apply the product, and removing any excess. “Typically, we see at least an inch-and-a-half penetration on a 4-in.-slab, or as much as a third to a half of the total thickness,” Rollins said.

Another benefit from using the SCP line of products to cure and/or seal concrete is that all jobs come with written warranties that guarantee that once concrete is sprayed with their products, it does not have to be done again according to Mike Foote, the Northeast Ohio, Omega Concrete Solutions franchisee.

Wilcox Tunnel

SCP recently completed its first foray into the tunneling market with the restoration of the Wilcox Tunnel in Chattanooga. Built in the 1930s and owned by the City of Chattanooga, the Wilcox Tunnel is the oldest tunnel in the area. It is a two-lane vehicular tunnel on the city’s east side that carries traffic under Missionary Ridge.

For more than eight decades, the tunnel performed its duties with minimal maintenance, but eventually water intrusion – and the subsequent cleaning and maintenance – began to take its toll. Eventually, the city explored options to rehab the tunnel and opted to line the interior with SPC technology.

“A lot of leaking was happening in the tunnel, and with those leaks would come calcium-based salts that would leave their marks on cars,” Rollins said. “The city was getting a lot of complaints, so they made the decision to rehab the tunnel. Initially they tried injection grouting, but when progress was slow, they tried treating the tunnel walls with SCP products, which stopped the water intrusion, allowing the epoxy injection to be completed successfully.

Before liner improvements, maintenance cost the city one week of labor and traffic management. Now, the city can clean the tunnel and reopen to traffic in just one day. Savings on maintenance with the liner upgrade are estimated to be $100,000 a year.

SCP also completed two other tunnel projects. When needing to stop the moisture movement through subterranean pedestrian tunnels, a leading defense contractor turned to SCP products to treat the shotcrete tunnel. The work was completed in 2017 and performed beyond the customer’s expectations. Officials at the Perth Mandurah railway tunnel turned to SCP in 2017 to help solve water migration problems into the tunnel. By treating the tunnel walls with SCP products first, the project reduced the amount of projected crack injection by approximately 80%.

SCP says another benefit of the product is that because of its ability to prevent water infiltration, it has the ability to help protect against concrete corrosion, including steel reinforcement, particularly in saltwater environments. “By shutting off saltwater migration, you can extend the life of concrete significantly by keeping the salts away from the reinforcing steel,” Rollins said. “That is true for basements and foundations in addition to tunnels.”

For further information contact:

Brent Rollins | Vice President of Business Development
Spray-Lock Concrete Protection, LLC

Bob Banka | President
Omega Concrete Solutions

Mike Foote | Franchise Owner

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