Characterization of per- and polyfluoroalkyl substances in crushed concrete from a source with known AFFF exposure: Outlooks for recycling.

Portland Cement Concrete (PCC) pavement is a highly recycled material globally. Recently, it has been discovered that some PCC pavement at military installations, firefighting training sites, and aviation facilities was vulnerable to per- and polyfluoroalkyl substances (PFAS) exposure via use of aqueous film forming foams (AFFF). However, little is known about the distribution of PFAS within intact PCC pavements, nor the implications of recycling AFFF-impacted PCC pavements. In this study, approximately 4,500 kg of PFAS-impacted concrete slabs collected from a former defense installation (in the United States) were processed in a full-scale recycling operation. Surface powder samples (< 0.25 cm depth) and pavement cores were collected from select slabs to screen surficial PFAS concentrations and characterize PFAS as a function of pavement depth. Additional clean PCC was processed, after the impacted load, to monitor potential PFAS transfer to subsequent material prepared by the same recycling equipment. Samples were analyzed for 40 PFAS via ultra-high pressure liquid chromatography - tandem mass spectrometry (UHPLC-MS/MS). Weighted averages from PCC depth profile analysis were more effective in estimating the boundaries (1,300 – 4,300 µg/kg) of expected sum of PFAS concentrations (ΣPFAS) in the homogenized final product (HFP) of crushed concrete (average 2,320 µg/kg) than surface screening concentrations alone (504 – 60,400 µg/kg). PFAS transfer to clean concrete crushed immediately following the PFAS-laden load was minimal, where the ƩPFAS decreased from 27 µg/kg to 9 µg/kg within 4,500 kg of clean PCC processed, and to below limits of quantification within 5,400 kg of clean PCC processed. • AFFF-impacted portland cement concrete slabs collected from former US defense site • Maximum PFAS concentrations were observed 0.25 – 3 cm from concrete surface • 4,500 kg of slabs were processed in a full-scale concrete crushing/recycling plant • Depth profile averages effectively estimated PFAS concentrations in crushed product • Low PFAS transfer to subsequent concrete; cleared within 5,400 kg clean material