PFAS contaminated asphalt and concrete-Knowledge gaps for future research and management

Per- and polyfluoroalkyl substances (PFAS) are now widespread in the environment. Globally, airfields and paved firefighting training surfaces are particularly affected due to extensive use of aqueous film forming foams (AFFF). This PFAS contamination in exposed concrete and asphalt has not been widely addressed. This review focusses on PFAS interaction with concrete and asphalt, traversing extraction, analytical identification/ quantification, PFAS fractionation via differential adsorption on organic and inorganic substrates, and reuse options for contaminated concrete and asphalt. A total of 24 knowledge gaps and management challenges for concrete and asphalt characterisation and management have been identified: center dot Identification and quantification: Six gaps: extraction/analysis of PFAS from concrete and asphalt (laboratory- and field-based); measure of total precursors; distribution in concrete and asphalt constituents; bitumen, aggregate and concrete compositions; enhanced PFAS transport. center dot Leachability: Eight gaps: distribution/incursion of PFAS into concrete and asphalt; sorption/desorption of PFAS from constituents; PFAS fractionation in asphalt and concrete; PFAS transformation; leaching from contaminated concrete and asphalt; co-contaminants; linking PFAS leachability with bioavailability; total load and leachability in PFAS management. center dot Reuse and repurposing: Six gaps: role of processing (surface area, new constituents) on PFAS mobility; temperature; sorbents/binders and degree of coverage, penetration and water repellency; coating/encapsulation; sealants; management of PFAS contaminated concrete and asphalt waste materials. center dot Aviation specific management of concrete and asphalt: Four gaps: understanding current and historic PFAS sources and hotspots; tracking of fate of potentially PFAS-contaminated concrete and asphalt materials; runway millings/ regrooving debris sampling and analysis to assess near surface PFAS-contamination; environmental trigger values for management.