University of Connecticut

Amount Appropriated?

$4.0M

FFID tracks stages 1–2 — stages 3–5 vary by agency, assistance type, and earmark structure.

Project Description

For more than 30 years, a regional concrete supplier in Connecticut and Massachusetts unknowingly used an aggregate from a nearby quarry that contained unusually high levels of an iron sulfide mineral called pyrrhotite. Over time, in the presence of water and oxygen, the pyrrhotite will oxidize and form iron oxides and sulfuric acid. Both the iron oxides and sulfuric acid damage the concrete over time by expanding within the concrete. This expansion causes the concrete to crack, lose strength and eventually deteriorate to the point of no longer being structurally sound.\r\n \r\nThere is presently no established method or risk-rating system to estimate how many will need to be replaced or how many can be saved with mitigation methods before they reach the status of damage that replacement becomes the only option.\r\n \r\nTo remedy this problem, a risk rating scale is currently under development at UConn utilizing a combination of field-based forensic data and laboratory-based tests, to anticipate the potential damage on a house depending on the pyrrhotite content and other conditions that affect structural deterioration. This rating scale will ultimately be used to prioritize houses requiring remediation as well as providing guidance to assist with the real estate market. To date, progress has been made towards the development and implementation of a test method that allows for the acquisition of consistent data. The expansion of data collection is critically needed to obtain an adequate base for the development and validation of the risk-rating system, as well as moving the test method towards an accepted standard that can be adopted by commercial and research laboratories nationally and internationally. From a mitigation standpoint, there is also a need to expand testing chemically treating, drying and sealing concrete containing pyrrhotite-laced aggregate to try and slow or stop the oxidization process.\r\n \r\n