By Marcelle Dibrell
Pool builders in central Texas have got a really big problem.
It’s called concrete cancer, and it has afflicted potentially thousands of swimming pools that were built in the region between 2016 and 2022.
Now, hundreds of pool owners are suing their builders because their newly built pools won’t hold water and are riddled with major cracks.
The problem is destroying people’s reputations, and it is bankrupting pool construction companies. Some reputable builders face losing their homes and their ability to provide for their families.
It is making a bad name for the pool industry, and it’s not really fair.
Through little fault of their own, in recent years, central Texas pool builders have been dealing with a bad concrete mix. And because of that, their pools have succumbed to something called an Alkali Silica Reaction (ASR), otherwise known as “concrete cancer.”
It shows up as cracking throughout the pool shell. It begins with random, eggshell cracks that appear all over the pool. It leads to deep fractures within the concrete. It’s not just unsightly — it totally undermines the
Alkali Silica Reaction or Concrete Cancer destroyed A.J Miller’s pool and spa in Austin Texas. Photo Credit: A. J. Miller, Pool Owner and victim of concrete cancer. Cancer
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pool’s ability to hold water.
And there is no way to fix it. According to cement experts, the Alkali Silica Reaction is caused by a reaction between the alkali components of cement and reactive aggregates containing amorphous silica. Specifically, certain types of silica aggregates will react with alkali hydroxide to form a gel. This gel swells as it adsorbs water from either the cement paste or the surrounding environments (pool water). The gel can create enough force and pressure that it will break through the concrete.
The cracking reactions are irreversible. Builders have attempted to make repairs to the cracks only to have a shattered pool surface reappear within a couple of months.
Bo Barnett, owner of KB Custom Pools, is an award-winning pool builder in Austin who is currently facing nearly two dozen lawsuits from customers whose pools have all been afflicted. He’s been building pools for more than 20 years, and until five years ago, he’d never even heard of ASR.
Now, he has pictures of his awardwinning pools that have been ruined by it.
Barnett said he has lost the confidence of numerous clients after attempting repairs on their pools. None of his repairs could save the pools.
With no help from his insurance company, he has been forced to declare bankruptcy.
“The fear of losing my ability to provide for my family has been the biggest problem,” Barnett said. “That, and seeing the heartache that this phenomenon has caused my clients. It’s been almost equally devastating.”
Barnett says that the ASR epidemic of central Texas was compounded by the boom in pool construction that the industry experienced shortly after the start of the COVID pandemic.
They say that everything is bigger in Texas. And in central Texas alone, pool growth was up 185 percent after 2019, Barnett says. He said there was a huge explosion of income and tech money coming into the area from people who had recently moved there.
“They’ve never been in Texas; it’s hot; they want a swimming pool,” Barnett said.
Barnett estimates there are probably thousands of ASR-afflicted pools in the area — he personally knows of two builders alone with 250 cases each. And from his own experience, he doesn’t believe it started happening because pool builders were cutting corners. Rather, he believes it happened through their ignorance about a recent change that concrete suppliers made to their cement mix.
He says that for a variety of reasons, there has been a limited supply of a substance called fly ash, which is a pozzolan — a substance commonly added to the cement mix to improve the strength of the final product.
Fly ash is a powdery material composed mostly of silica made from the burning of finely ground coal. It has a low pH, and when it is added to the mix, the silicates react with the lime in the cement — calcium hydroxide — to form calcium silicate hydrate. Fly ash and other pozzolans consume the excess lime, making a denser, less permeable product that is less susceptible to water intrusion. Experts say pozzolans significantly reduce or even eliminate the Alkali Silica Reaction.
Paulo Benedetti, one such expert, writes that in recent years, concrete suppliers have found it difficult to find fly ash and other pozzolans. So, they simply eliminated it from their mix. It is possible that contractors noticed that their mix designs showed zero fly ash, but most didn’t give it any more thought than that.
Now, those contractors are paying the price.
Barnett says to prevent ASR, contractors must ensure that the concrete provider is selling “engineered aquatic concrete.” That, he says, will ensure that it contains fly ash. Second, he says contractors need to obtain the batch sheet from the delivery truck so they know exactly what is in the concrete mix. This can be difficult, because some concrete suppliers don’t want to supply this information.
www.Kbcustompools.com.
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“What you need is 25 percent Grade T fly ash in a shotcrete application,” Barnett said. “And you will need 10 percent Grade T fly ash in a gunite application.” He explained the reason you need so much more in shotcrete is that the aggregate size is much larger than the sand used in gunite.
But there’s another component to ASR, and it has to do with the aggregate used to make the concrete. Where it comes from matters. That’s why this problem seems to be concentrated in central Texas, rather than all over the country.
“Know your aggregates,” Benedetti writes. Because transportation costs are high, most aggregates are sourced and used locally. This explains why ASR tends to be a regional phenomenon, where different areas of the country may source their aggregates from rock quarries, lake or river bottoms, or surface mines that may contain more or less of this reactive silica (usually found in quartz, quartzite, siliceous dolomite, siliceous limestone, siliceous shales, opals, chert, and andesite rhyolites). Barnett says most of the aggregate material used in central Texas is mined out of the Colorado River. Unless builders are going to significant expense to find alternate aggregate, they are probably using something local, which is definitely reactive aggregate, he says.
Austin resident AJ Miller had his pool built in 2020, and his pool was destroyed by ASR. He’s worried about foundation issues reaching his house. He said he feels bad for his pool builder, who built a lot of afflicted pools and is now out of business. He estimates that there are perhaps 10 other pools in his neighborhood that also have ASR. Miller is among hundreds of pool owners who are in litigation with the companies involved in building ASR-afflicted pools.
Benedetti writes that between the aggregate and concrete suppliers and the pool builders, there is simply not enough money to go around to the number of customers whose pools must be removed.
Some contractors are now facing devastating financial ruin with loss of personal assets. Some business owners have gotten ahead of potentially devastating settlements by dissolving their businesses and declaring bankruptcy. Either way, companies are losing the good reputations that they have spent decades building. Ultimately, ASR will leave hundreds of customers out hundreds of thousands of dollars with homes that are difficult if not impossible to sell.
