With many DoD platforms having their lifetimes extended, structural repair is essential to maintaining aging fleets. Sructural materials on weapons systems generally must possess unique properties in order to function in demanding operational environments. Manufacturing and maintaining structural materials with unique properties has often required the use of toxic or hazardous chemical substances. SERDP and ESTCP are developing and demonstrating the science, tools, and techniques needed to meet critical defense performance criteria while also reducing the impact on the environment and protecting the health of DoD workers and military personnel.