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Cobiax: An innovative and sustainable addition to concrete construction

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The approach to pouring concrete foundations has, traditionally, been solidly set in stone. Not anymore – now its air. At the new Schneck Medical Office Building (Schneck MOB) in Seymour, IN, F.A. Wilhelm Construction (Wilhelm) is using the Cobiax system, a revolutionary way to mold concrete around void former modules cast from recyclable material and filled with air. The result is an eco-friendly, budget-friendly foundation with the same stability and stiffness gleaned from traditional methods, all while using less material and time to construct.

Cobiax is a brand that offers plastic formers to insert into concrete in varying shapes and sizes dependent on the end goal of the structure, the spans, and the slab thickness. Although relatively new in the United States (Schneck MOB is only the 10th building in the nation and the first in Indiana to use this technology), the system is widely used throughout Europe. According to Mike Russillo, President of Cobiax USA, the idea has been around for a long time, we just redefined the concept.

“They call it a voided slab system. Adding voids in concrete slabs is something that’s been going on for years, but this is a newer way, an innovative way of doing it. By putting voids in, we eliminate concrete which eliminates weight. By eliminating weight, we can have spans, significantly large spans, without beams,” says Mike Russillo, President of Cobiax USA.

Employing the technique

According to Wilhelm’s Quality Assurance Manager Larry Arthur, project owners are presented with many early design and construction considerations when opting to build a new facility. Engineering firms are tasked with evaluating each building based on sustainability, preference, and ingenuity, and with offering insight and solutions for best value delivery. They did just that with the Cobiax system for the Schneck MOB.

“The engineering firm considers all the information from the manufacturer and creates a model based on – what they need, how many voids, where they need to be placed, how they need to be placed – so it’s a detailed process,” Arthur said.

Schneck MOB is set to be a five-floor structure requiring open space within the completed building. The use of the Cobiax technique enabled engineers to create a platform that utilizes fewer columns, yet still provides the amount of support needed to construct a sustainable building with more open space and larger spans between columns.

As the first building in Indiana to use this technology, a few challenges were anticipated but Wilhelm counteracted with solutions.

“Find out the ins and outs. It’s not a complicated system but because it’s new, the fear of the unknown can make people shy away from, or not try to do things. [Wilhelm was] not afraid of it and wanted to learn more about it.” Russillo remarked in regard to Wilhelm’s usage of the Cobiax system.

Prior to the Schneck MOB project, Wilhelm team members traveled to the Kennedy Center in Washington D.C. where Lane Construction employed the technology. The initial research on Wilhelm’s end led to seamless delivery at the Schneck MOB project.

The difference is in the pour

The Cobiax system differs from flat concrete, post-tensioned, and waffle slab decks and/or other deck variety pours in a multitude of ways.

When pouring for this method, a mat of rebar is laid down followed by a cage of the voids, topped with another mat of rebar. Concrete is filled to just above the bottom wires of the cages that contain the voids and begins to harden around the bottom of the cages before the rest of the concrete, covering the Cobiax and the top layer of rebar, is poured.

The first layer of concrete serves the purpose of holding the cages, preventing them from floating to the top while the remainder of the concrete is applied. The second layer forms around the voids without penetrating, breaking, or filling them.

Benefits and savings

The main benefit of this system is the smaller carbon footprint. The process of making cement emits carbon dioxide. With Cobiax technology, less cement and concrete (fewer concrete trucks) are used generating less CO2. Furthermore, the slabs are typically thinner than those structures that use alternate methods making the entire slab lighter. This allows for a decreased amount of support beams and more floor spaces.

Cobiax is comparatively thinner than structures utilizing steel beams or beam and slab decks. These alternate methods result in greater depth due to the steel within the concrete. Where you might have a 10-inch slab with Cobiax, other methods could have a 14- or 16-inch depth, resulting in a taller building. The shorter building enables owners to save on heating and cooling costs over the lifespan of the building.

Further savings can be realized as there are no long-term maintenance issues with this system, Russillo explained.

“The voids are in the concrete, and they’re there forever, or until you take the building down. Then it’s just like anything else. There’s nothing different after the concrete is poured. There’s no maintenance issue, it’s a concrete slab. One of the benefits of concrete – it’s not going to rust on you. It’s pretty long lasting, or in today’s terminology, sustainable” Russillo said.

While the Schneck MOB is the first structure to use Cobiax technology in Indiana, according to Russillo, it’s the 10th in the United States. As the method gains in popularity, Cobiax USA anticipates three to four new projects adopting the technique in the very near future.

For more information contact Wilhelm at and/or Cobiax Technology at

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