The goal of this project is to gain in-depth, spatially-resolved knowledge on accumulation of per- and polyfluoroalkyl substances (PFAS) in asphalt and concrete due to the use of aqueous film-forming foam (AFFF). The overall objective is to systematically evaluate available methods for preventing continued emissions of PFAS from both in-place pavements and aggregates formed from recycled, crushed construction materials. The specific objectives are to: 1) systematically investigate the spatial distribution and extent of PFAS-impacted concrete and asphalt associated with fire training areas, fire stations, crash sites, aircraft hangars, and equipment testing areas; 2) evaluate existing strategies for surface treatment of pavements including commercially available sealants, cleaning agents and surface renewal strategies; and 3) investigate strategies for beneficial reuse of excavated construction materials using commercially available sealants, cleaning agents and incorporation of aggregates into new concrete, to manage the risk of PFAS release.

The technical objectives of this project will be achieved through field sampling, bench-scale laboratory experiments, and advanced analytical techniques. AFFF-impacted concrete and asphalt, including subsurface aggregate support and soils, will be sampled from fire training areas, fire stations, hangars, and crash sites to represent different surface features and conditions. Materials will be sectioned and spatially-resolved samples will be drilled or crushed to fine particle sizes, followed by multiple solvent extractions. Environmental Protection Agency (EPA) Method 1633 will be used to analyze target PFAS, and sample extracts will also be analyzed by nontarget high-resolution mass spectrometry for suspect screening of additional PFAS. Surface samples corresponding to sites with high PFAS concentrations will be evaluated via a suite of advanced techniques including ion beam analysis, imaging, and direct mass spectrometry. Materials will be evaluated for the potential to serve as long-term PFAS sources via stormwater runoff using both equilibrium batch testing and under flow conditions. Impacted surfaces will be subjected to a number of commercially available treatments and sealants to test the ability of these treatments to remove or bind PFAS and prevent future environmental release. Leaching tests and surface microstructure analyses will be used to evaluate the efficacy of additives to bind PFAS during recycling of aggregate material into new concrete for beneficial reuse.

Successful completion of this project will provide important new data on the spatial distribution and potential for re-emissions of PFAS in impacted asphalt and concrete pavements. A variety of surface and aggregate treatments will be tested to prevent further emissions of PFAS from in-place and recycled materials. These data will be of critical value to the many locations where long-term AFFF-impacted use on pavements has occurred. (Anticipated Project Completion - 2027)