Alkali-Silica Reaction (ASR) has been a long-standing issue in the concrete industry (think highways, bridges, buildings) dating back to the 1940s. Because swimming pools are subject to water 24/7, special care needs to be taken in laying concrete for pools, including following important codes and standards from the Pool and Hot Tub Alliance (PHTA) and the American Concrete Institute (ACI). ASR damage in concrete pools can be substantial, leaving homeowners with little to no choice but to replace the pool.
ASR — also known as “concrete cancer” — 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 pool’s ability to hold water. And there is no way to fix it The impact on pool builders can be substantial because there is often a delay in the signs of ASR, sometimes taking more than two years to appear. If pool builders are unaware of mix changes, many pools can be built without knowledge that the concrete does not meet the requirements for building pools.
Currently, there are several locations in the United States experiencing “outbreaks” of ASR, most notably Austin, TX. However, this situation can happen anywhere that there is a breakdown in communication between the concrete providers and the pool builders. The situation in Austin, for example, was due to a shortage in fly ash and concrete providers not informing the pool builders that they were not including it in the mix when it was hard to source.
Class F fly ash is not the holy grail for pool builders, but it is a safeguard that helps eliminate or severely reduce the impact of ASR. Adhering to ACI Code 318 is the best start, followed by mandating Class F fly ash in shotcrete mixes. Another way to reduce the risk of ASR is to make sure builders get a copy of the mix ticket at time of delivery. If the subcontractor cannot provide it, builders should turn the order away. Finally, the impact of the central Texas situation has resulted in insurance companies requiring pool builders use a master agreement with their concrete subcontractors. An example of a master agreement is available on PHTA’s members-only website.
The PHTA is monitoring the ASR situation and will continue adding resources to its webpage. The association also has a ASR Task Force made up of professionals from the pool industry, including builders, ACI representatives, National Plasterers Council (NPC) representatives, insurance agents, and expert engineers.
To reach the ASR Task Force, contact Jeff Henriksen, PHTA’s Chief Strategy Officer, at jhenriksen@phta. org.
ASR Sample Contract
If pool builders want to reduce their risk of ASR happening in their pools, they need to establish a more formal relationship with their concrete subcontractor. This includes having a written and executed subcontractor agreement. Pool builders should also have these types of agreements with any other subcontractors or parties providing materials or performing work on job sites.
The subcontract should clearly specify the work to be done; quality of materials to be used; require subcontractors carry adequate insurance policies; and include an indemnification clause, to name a few of the items to include. Making sure builders have mix tickets is also a safeguard. In terms of insurance, many carriers are trying to exclude silica. A solution offered by an insurance broker is to carry a pollution policy that does cover silica in the pool and air.
Note: While PHTA endeavors to provide useful information for its members, it cannot provide legal or insurance advice. Pool builders and service professionals should consult with their own legal counsel and insurance professionals to tailor an approach best suited for their business and circumstances.
