Pyrrhotite and Crumbling Foundations

Pyrrhotite and Crumbling Foundations

Last July, hundreds of Connecticut homeowners were horrified to find that their home foundations had begun crumbling beneath their feet. The cause? Large amounts of an iron sulfide mineral within the concrete aggregate. If you’re concerned about the structural integrity of your builds, here’s what you should know.

What Happened?

In the summer of 2016, the Connecticut Attorney General’s office received hundreds of complaints about crumbling foundations. After investigating the reports, state authorities determined that the source of the problem likely originated in the mineral content of a stone aggregate mined in an eastern Connecticut quarry. According to reports, this content included an iron sulfide mineral called pyrrhotite, which allegedly led to rapid deterioration of the aggregate.

Essentially crushed gravel, sand and stone, concrete aggregate is combined with water, cement and sometimes other additives to produce concrete. In this case, the presence of pyrrhotite appears to have hastened deterioration, leading to irreparable damage on at least 400 Connecticut homes.

In a written statement, Connecticut Attorney General George Jepsen said his office believes there is sufficient evidence to conclude that pyrrhotite was a substantial contributing factor to the crumbling foundations experienced by many local residents. That said, he also stated that more research will be needed to determine if other contributing factors were at play.

According to some industry experts, it’s not clear why pyrrhotite would foster deterioration in concrete aggregate, especially since the mineral is commonly found in varying concentrations in igneous rock. Some have suggested the problems actually stem from installation issues; however, the Connecticut Attorney General’s office continues to stand by its assertion that pyrrhotite concentrations played a key role.

Whatever the ultimate cause, widespread foundation problems have affected at least 400 homes, and some experts believe that number could ultimately rise to 10,000 in time. To repair their properties, Connecticut homeowners are expected to pay a total of $1 billion collectively. What’s worse, neither home insurance providers nor the state or federal government appear to be willing to help with these expenses.

What Builders Should Know

Currently, the two companies at the heart of the matter – Becker Construction, in Willington and J.J. Mottes Company, in Stafford Springs – contend that the mere presence of pyrrhotite is not enough to cause such rapid foundation deterioration. In turn, they believe other elements are at play. Despite these assertions, both companies have signed agreements with the state AG to stop selling materials for residential foundations containing aggregate from Becker’s Quarry in Willington.

If you’re concerned about the foundations on your projects, talk to your supplier to determine how and where the company gathers its materials. You should also always follow best practice guidelines for your foundation builds. Finally, if a buyer has expressed concern about the long-term integrity of a property’s foundation, consider offering a ten-year structural warranty, which provides full coverage for any potential issues that could arise in the future.

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