Project Description:

The mobility and subsequent release of PFAS within concrete structures has been identified as an immediate concern by air and maritime transportation industrial entities, however, very little is known about the rates of ingress and egress of PFAS. Identifying the rates of sorption/desorption from concrete will allow for a more thorough assessment of site remedial needs and help better understand the pathways of PFAS transport from release to concrete, soil, groundwater, etc. Regulation of several PFAS has occurred in many states, including states with production facilities and military sites. There are over 9,000 compounds in the PFAS family, of which many bioaccumulate and persist in the environment. Although the distribution of AFFF in concrete is dependent on the specific composition of the AFFF and the concrete, the overall controlling factors of vertical and lateral PFAS distribution are application rates, co-contaminants such as hydrocarbon fuels, and durability of the concrete. Even though there has been a transition away from PFOS and PFOA based AFFFs, application areas have already been contaminated, along with other perfluoroalkyl carboxylic acids (PFCAs), perfluoroalkyl sulfonic acids (PFSAs), and fluorotelomer sulfonates (FTSs). Extensive studies have been undergone to determine the fate and transport of PFAS in soil and water, however, extraordinarily little is known about PFAS in construction building materials, particularly with respect to concrete itself. This project will analyze the leaching potential in surrogate AFFF-impacted concrete samples and assess the continued leaching of PFAS undergoing carbonation, freeze-thaw cycling, salt penetration, and a combination thereof.

US DOT Priorities:

Investigating the rates of PFAS (per- and polyfluoroalkyl substances) sorption/desorption within concrete, particularly under various conditions like carbonation and freeze-thaw cycling, addresses concerns within transportation industries regarding PFAS mobility and release in concrete structures. This research fills a critical knowledge gap as little is known about PFAS in construction materials. By understanding PFAS transport in concrete and potential leaching, the project contributes to environmental protection and informs strategies for managing PFAS contamination in transportation infrastructure.

Outputs:

A successful project will correlate PFAS leaching potential to concrete durability under various environmental conditions and lead to future testing of PFAS leaching potential of aged concrete cores from sites with a variety of environmental conditions. Additional future work could include the determination if coating of concrete samples in specific sealants will slow or stop the leaching of PFAS from concrete. Specific project objectives include the following:

• Provide multiple lines of evidence of PFAS leaching potential and their relationship to concrete durability.
• Determine the PFAS leaching potential of concrete samples under simulated rainfall events.
• Assess if PFAS impacts the durability of concrete over time.

Outcomes/Impacts:

Health advisories for PFAS are being shaped prior to thorough understanding of relative location, spatial distribution, and transport through medium. Our understanding of PFAS movement in the environment, especially with respect to air and water-based transportation systems, is extremely limited and the ability to make sound decisions to protect the user from harm is hindered by our lack of understanding This study will address the leaching potential of PFAS under a variety of weather conditions that directly correlate with concrete durability. The determination of PFAS ingress as well as egress and their related kinetics will aid in projecting the magnitude of PFAS loading into the environment from concrete, and support assessments of PFAS related limitations on concrete structures. As a secondary objective, the study will seek to determine if specific sealants slow or prevent the leaching potential of PFAS in concrete. Cost savings may be realized as a structure’s life is extended or limited, workable sealants are found, and/or other alternatives are discovered.

_{Figure 1: Schematic of the proposed system: 1) Arrays of PV/T System, 2) Header tank with a closed loop system and 3) RHS loop.}