Strengthening Concrete with CFRP

Concrete is durable, affordable and easy to use. That’s why it’s such a common building material. But like all building materials, it’s not perfect. Sometimes, concrete degrades over time. It gets weaker, and the ability of structural elements to bear the load comes into question. When the integrity of a building is at stake, there’s no room to doubt whether the building’s concrete is up to the task.

That’s why concrete strengthening is such an important service. It’s a service we provide at Tendon Systems, but we do it in a variety of ways, depending on the unique circumstances of the project. One of those ways is called FRP, or fiber-reinforced polymers. 

You may not be aware when you see FRP strengthening concrete structures, but you probably see it all the time. In this post, we will dive into FRP and carbon fiber-reinforced polymers (CFRP), how they work and how they compare to other methods of strengthening concrete. Read on to learn more.

FRP and CFRP are key offerings among our suite of concrete services. If you’re ready to make your concrete stronger, we have the solution for you. Reach out to the team at Tendon Systems.

Definitions: FRP and CFRP

Applied to structural strengthening, FRP is simply high-strength fibers woven together to create a sheet of extremely strong material. FRP reinforcement is the task of applying these FRP sheets to existing concrete with a strong adhesive. 

The fibers used in FRP can be made of a number of materials. Steel wires, fiberglass and carbon are the most common fiber materials, but carbon is the strongest in terms of durability, stiffness and tensile strength. Using carbon fibers for FRP reinforcement is called CFRP. This method is becoming increasingly popular in concrete reinforcement because of its superior strengthening properties.

How CFRP Strengthens Concrete Structures

Concrete construction professionals can point to plenty of examples of CFRP strengthening concrete structures, but how, exactly, does CFRP get that job done? How can it actually help a concrete slab support a heavier load?

We’ll try to avoid too much engineer lingo as we walk through this concept. The interlaced fibers of a CFRP sheet provide a lot more load-bearing and impact-resisting value than their small profile would suggest. These stiff sheets of carbon fibers bind concrete slabs, columns and beams together, giving the overall structure a greater resistance to external stresses. 

Additionally, the strong adhesive used to bind the CFRP sheets to the concrete helps to hold the structure together when it would otherwise crack. Correctly applied CFRP adhesive essentially merges the CFRP and concrete, adding a strong, new layer. Because the fibers are in perfect contact with the concrete due to the adhesive, loads are transferred to the carbon fibers instead of remaining solely on the aging or degraded concrete.

The Rise of CFRP

The rise in CFRP is due to the many benefits it brings to concrete restoration projects. Some of those benefits include the following:

• CFRP sheets can be applied to the outside of existing concrete, which means you don’t have to do expensive, invasive renovations to make the concrete stronger.
• CFRP is thin, so it doesn’t expand the profile of the concrete by much or make it less visually appealing.
• CFRP sheeting is resistant to corrosion from chemicals and the elements.
• CFRP can be cut and fitted to the exact specifications of nearly any straight or slightly curved concrete structure.

What About Post Tensioning?

Post Tensioning is generally used as the primary reinforcing system in a newly constructed building. It’s a method we use often at Tendon Systems.

Post-tensioning involves the placement of pre-stressed steel cables in forms before concrete is poured. It adds considerable strength to any concrete slab. It’s the gold standard for concrete reinforcement. While post-tensioning is done at the time of construction, a trained concrete restoration professional can repair corroded or compromised post-tensioning tendons to strengthen existing concrete.

The following are some of the key benefits of post-tensioning:

• Post-tensioning strengthens slabs, which allows them to be thinner. This reduces costs and allows for greater design flexibility.
• Post-tensioning is highly effective at preventing cracks from concrete shrinkage.
• Post-tensioning done with high-quality materials is highly resistant to corrosion and has a long lifespan.

CFRP and Post-Tensioning

In many cases, CFRP is used to supplement concrete structures that are also benefiting from the reinforcement of post-tensioning or conventional rebar. 

Of course, the exact methods used to strengthen the concrete in your building are going to depend on the unique details of your situation. The unique benefits provided by CFRP come with a high price point, and therefore would only be used as a repair material or to support the main system. That’s why it’s best to speak with a concrete restoration expert who will know which strategy is best. 

Tendon: 30 Years of Experience Strengthening Concrete Structures

Concrete used in homes, commercial buildings, parking decks and the like has to be strong. Otherwise, people’s lives and livelihoods are at risk. That’s the business we’re in — making concrete strong again.

Depending on the details of the project, that will sometimes look like post-tensioning repair and sometimes look like CFRP. The team at Tendon Systems has expert knowledge of both methods. In fact, we bring more than 30 years of experience strengthening concrete with CFRP and post-tensioning repairs to the table for our customers.

If you’re ready to take advantage of that experience, we’re ready to hear from you. Give us a call at 678-835-1100 or contact us online today.