The last thing any concrete pool owner wants to hear is the dreaded phrase “concrete cancer.” Concrete cancer or Alkali-Silica reaction is a term used to describe the chemical reaction that occurs when the steel used to reinforce concrete starts to rust, corrode, and expand. While concrete cancer can occur in any concrete structure that uses steel walls or beams it is especially common in concrete pools. In this blog post we’ll be diving into what concrete cancer is, how to spot it, and how to prevent it.
What is concrete cancer?
As stated above, concrete cancer is the reaction that occurs when moisture comes in constant contact with the steel walls and beams used to reinforce the concrete. That’s the cliff notes version now let’s dive in a little deeper. Concrete is porous meaning that it is constantly soaking up moisture in the air and water. Not only that but concrete cracks, even hairline cracks can allow moisture to seep into the concrete and come in contact with the beams. Over time the exposure to moisture and air will cause the steel to corrode, rust and expand. This causes concrete to shift and crack; this reaction spreads rapidly hence the name: concrete cancer. Concrete cancer left unchecked can be dangerous as it will compromise the integrity of the structure. While any concrete structure is susceptible to concrete cancer, concrete pools are more prone to it.
What causes concrete cancer in pools?
Concrete is not naturally waterproof, in fact it naturally is constantly soaking up moisture. The only thing keeping the water in the pool and not in the ground is a thin waterproof coating. Spoiler alert this coating has to be refinished every few years due to it wearing off from age, poor maintenance, and natural wear and tear. Not only is concrete porous it also cracks. Older concrete pools, pools that haven’t been cared for properly, and pools that were installed poorly are all extremely prone to cracks. But age and poor maintenance aren’t the only factors that play into the development of concrete cancer. There are also many geographical factors that play into it. Concrete pools built near a body of water or salt air can accelerate the chemical reaction that causes concrete cancer. And as mentioned in a our blog post: Why Pools Can Pop: Concrete and Fiberglass improper drainage can cause concrete pools to crack. These cracks can play a major role in concrete cancer.
How to prevent concrete cancer?
The first step in being able to prevent concrete cancer is first knowing how to spot it and tell if your pool already has it. A good sign that your pool is developing concrete cancer is the appearance of rust on the outer walls of the pool. Eggshell-like cracks and parts of the pool caving in are also signs that your pool has concrete cancer. Now as horrifying as that all sounds it can be prevented with proper maintenance and regularly retouching your waterproof coating. If your pool already has concrete cancer then it can normally be repaired but you’ll have to hire a professional.
A common misconception around concrete and fiberglass pools is that concrete pools are just the easier option. That’s extremely false. It’s important to note that all pools require maintenance, and looking for an easy way around that will only lead to major problems down the road. With all that aside, concrete pools are drastically harder and more expensive to maintain. As mentioned before concrete pools are porous literally meaning they have pores. These pores are constantly soaking up moisture no matter how strong your waterproof coating is. Fiberglass pools on the other hand are naturally waterproof. With a smooth air tight surface they are not naturally soaking up water. Here at Pettit Pools our pools are made with the same resin gelcoat used on boats. If you go to any marina you’ll see fifty year old boats made with the same stuff our pools use. The rough surface of concrete pools not only cuts up your feet but is also the perfect habitat for algae and bacteria. So concrete pool owners be prepared to scrub your pool weekly. If you’re in the market for a pool save yourself the headache and choose the option that’s naturally waterproof.
Citations:
“What Is Concrete Cancer & What Causes It?” Latham Pool, 22 Oct. 2024,