Assessment of sealants for the mitigation of PFAS leaching from contaminated concrete.

There has been limited research on the presence, distribution and management of per- and poly-fluoroalkyl substances (PFAS) in concrete infrastructure exposed to historical use of aqueous film-forming foams (AFFF). Concrete sealants may constitute a rapid, effective in-situ mitigation option for leaching from PFAS contaminated concrete pavements and ex-situ for PFAS contaminated concrete waste piles. This laboratory study, using leaching and imbibition investigations, revealed six commercially available sealants as possible options to mitigate PFAS leachability from contaminated concrete. An epoxy polymer was the best sealant in preventing the leachability from and penetration into concrete. Two bitumen-based sealants performed well, however, their widespread use may be restricted due to their flammability, low reflectivity and heating susceptibility, thus eliminating indoor or hangar applications. Two additional polymer-based sealants (acrylic, polyaspartic) also demonstrated low PFAS leachability from and penetration into concrete. Polymer-based sealants (epoxy, acrylic, polyaspartic) meet a greater range of functional requirements for concrete, including high chemical and weathering resistance, UV resistance, wearability, and water repellence. Epoxy and polyaspartic sealants also acting as effective PFAS adsorbents may also prevent off-site transport of PFAS leaching from concrete. A combination of surface and penetrative sealants is likely to best meet operational and management requirements at sites with respect to new and aged PFAS contaminated concrete.