Comprehensive state-of-the-art report for long-term behaviour of concrete structures in repository environment

Reinforced concrete is widely used in nuclear disposal facilities, especially those for low and intermediate level wastes (LILW). The design service life of modern concrete is however no longer than about 100 years. During this time, it has been noticed that the material gives a good performance in many environments, however several chemical aggressive species in water, soil or the atmosphere may react with the cement mineralogical phases and weaken its integrity. The challenge of concrete in LILW nuclear disposal repositories is therefore its long-term stability. The reinforced concrete in disposal repository has a design life of at least 500 years and therefore, these structures should remain durable until this target service life is fulfilled and no sudden failure should occur after this period. The aim of this state-of-the art report is to study the following topics related to the performance of reinforced concrete structures in the final disposal repository condition: (i) the factors affecting the long-term behaviour of concrete structure in underground waste repositories, (ii) the transport process of chemical ions in cementitious materials, (iii) the deterioration mechanisms of concrete structures at final LILW disposal condition and (iv) the interaction between of concrete structure deformation, cracking and external stresses and the behaviour of concrete structure and their service life under disposal conditions.