Limited field data are available from reinforced concrete specimens exposed to environmental conditions and subjected to severe deterioration by Alkali Silica Reaction (ASR) and/or Delayed Ettringite Formation (DEF). A large-scale reinforced concrete specimen is subject to ASR/DEF deterioration for five years. Strain measurements indicate that both transverse and longitudinal reinforcement yield within six to twelve months of field exposure. Recorded surface strains compare well with the internal steel and concrete strains. Transverse expansion strains markedly exceed longitudinal expansion strains. Although ASR/DEF deterioration may cause severe surface cracking and possible reinforcement corrosion in the long-term, its effect on the structure's load carrying capacity remains unknown at this time. © 2016 Elsevier Ltd