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When upgrading a building floor, structural integrity can be compromised. As various stresses are applied, shear cracking can occur. These cracks occur due to the development of a displacement discontinuity surface within the solid. If the displacement develops tangential to the surface of displacement, it is called a shear crack. Cracking can be a problem in many materials, specifically concrete slabs. The result, cracking in the slab, is a very expensive problem to fix. Concrete slab reinforcement can be used to prevent shear cracking as well as save time and money dealing with the problem. Because concrete is typically used for most structural applications, it is very important to ensure that there will be no damage as a result of cracking, or better yet, prevent the cracking all together.
HJ3 Carbon Fiber Reinforcement Slab Core Holes
120 Core holes drilled into the concrete flooring slabs of Terminal 4 in Sky Harbor International Airport before installation of HJ3’s custom carbon fiber reinforcement system.


The concrete slabs of Sky Harbor International Airport were very functional and well enforced until expansion required 120 core holes to be drilled through the slab and underlying rebar. As the holes were drilled, concern grew for the potential of shear cracking to occur over time. Since the core holes were cut into the concrete flooring slabs and rebar, there was concern over the potential shear cracking to occur over time. Replacement of the floor would been a long and costly job, so supplementary reinforcement by HJ3’s carbon fiber reinforcement system was used to provide additional reinforcement to both sides of the slab.
Concrete Slab Reinforcement
Installation of HJ3’s carbon fiber reinforcement system around a core hole, 9 inches in diameter, on the underside of the concrete slab.


To prepare the concrete slab for installation, specific requirements were required. The surface was cleaned and primed with HJ’s primer. A high modulus paste was then applied to the area surrounding the holes that required the reinforcement. It was determined that a crisscross patter would provide the most support for the holes. The carbon fiber reinforcement system was applied to both the top and underside of the suspended concrete slab. This is very important to the project because of the suspension of the slab. If the slab was grounded application on both sides may not be necessary. Additional flame resistance was required by the building codes so a saturant was applied to the system for protection.
Carbon Fiber Reinforcement
Professional installation of the carbon fiber reinforcement system.


Installation process for Sky Harbor International Airport slab reinforcement project.
Completed installation of HJ3’s custom carbon fiber reinforcement system for Sky Harbor International Airport.


HJ’3s carbon fiber reinforcement system is currently aiding in the strengthening of the concrete slabs in the international airport floor. Potential and future structural failure and shear cracking have been successfully prevented. Currently, the 120 holes in Terminal 4 are supported and Sky Harbor Airport has saved $800,000!!!! As the airport continues their expansion, HJ3 will be right there helping them support their suspended concrete slabs! If you have concrete slabs and a concern about shear cracking and would like to learn more about HJ3’s carbon fiber reinforcement systems, contact our project managers today at hj3pm@hj3.com.