Common problems with concrete pools

Cracks in pool shells or decks are often neglected by contractors since they don’t have a long-term repair and strengthening solution. Concrete can crack for a variety of reasons depending on its usage and the way the structure has been constructed.

Why does a pool crack?

Reasons for cracks in concrete pools (not limited to the following items):

1. Poor concrete mix
2. Insufficient thickness
3. Settlement
4. Hydrostatic pressure or ground movement
5. Freeze-thaw damage: the freeze-thaw phenomenon occurs when concrete is saturated with water, the temperature drops and water freezes inside the concrete. Since frozen water expands 9% of its original volume, it causes distress to the concrete structure and cracks can form
6. Deicing salts 
7. Lack of control joints
8. Lack of reinforcement 
9. Weak concrete

A pool’s cracks can allow moisture to work its way down from the surface and into the concrete, resulting in further crack expansion and deterioration around the area. Around 50% of crack repairs will crack again after 2 years.

Repair methods and solutions

Often cracks in pools and decks are repaired by injecting epoxy into the cracks. This kind of repair for deep cracks, which extends through the concrete, is a temporary solution and cracks will appear again. Some contractors fill the cracks with concrete, but it is just a temporary fix and does not add any tensile strength to the damaged sections; it provides only the bond strength which is not strong enough to prevent future re-cracking.

Repairing pools using carbon fiber is the best long-term solution. Using carbon fiber for the repair not only strengthens the crack itself, but also the affected area around the crack. Locking the crack in-place with a high-strength, non-corrosive carbon fiber reinforcement product will ensure the cracks will no longer pull apart after the pool is filled with water (Figure 1).

Advantages of using carbon fiber for pool repair

The most important advantages of using carbon fiber for concrete pool or slab repair are quality and cost savings. By installing a high-quality carbon fiber reinforcement product that is strong enough to support cracks and lock the pool wall or deck together on both sides of the crack, cracks are controlled and prevented from failing or opening again. The ultra-thin profile of the Rhino Carbon Fiber™ Concrete Crack Lock® stitch is fast, efficient and non-invasive to install. The stitches do not compromise the structural integrity of the concrete around cracks and provide a long-term solution for pool crack control.

In the past, contractors bent rebar in the shape of staples and had to drill and grind the concrete surface until the giant and thick staples could be installed flat across the surface. Rhino Carbon Fiber™ now has an ultra-thin dumbbell-shaped carbon fiber staple/stitch which is faster and cleaner to install than rebar, and provides a stronger, non-corrosive repair. Rhino Carbon Fiber™ Concrete Crack Lock® stitches directly lock into the concrete and will prevent future movement (Figure 2).

Rhino Carbon Fiber™ Concrete Crack Lock® stitches are a concrete crack bridging/stitching solution that repair and reinforce concrete cracks in pools, pool decks and more! The Rhino Carbon Fiber™ Concrete Crack Lock® stitch is an evolution of rebar/the concrete staple, developed to take full advantage of the carbon fiber’s tensile strength, decrease labor time and cost while providing a more aesthetic finished look (can easily be painted over or covered with a finishing product)! Carbon fiber is lightweight, easy-to-install, durable (10x stronger than steel*) and non-corrosive, which eliminates the need for maintenance. When installed and finished with a protective coating, there is no evidence of the installation.

Rhino Carbon Fiber™ Concrete Crack Lock® stitches benefits can be summarized as below:

• Repairs and reinforces concrete cracks, increasing structural integrity and seismic strength
• Less concrete is removed than other applications
• Less epoxy is needed to complete the repair
• Less time and labor is needed to complete the repair (cost savings)
• Takes full advantage of the carbon fiber’s tensile strength (other systems rely on the epoxy strength)
• Minimal aesthetic impact; can easily be painted over or covered with a finishing product
• Easy-to-install
• 10x stronger than steel*
• Non-corrosive; eliminates the need for maintenance

Authors
Parastoo Azad and Dr. Mehrtash Soltani (April 23, 2021)
*Note: the ‘10x stronger than steel’ claim is based on the comparison between dry fiber properties and grade 60 steel