Experimental study on the structural behaviour of calcium-leaching damaged concrete members

Degradation due to calcium leaching from concrete progresses very slowly compared to other types of concrete degradation. However, in the design of special concrete structures with service lifetimes of more than 100 years such as radioactive waste repositories, it is important to consider the effect of calcium leaching from the viewpoint of durability. For this reason, a considerable amount of research associated with calcium-leaching degradation has been published, with most of these studies mainly focused on changes in the intrinsic properties of cement-based materials due to leaching attacks. In contrast, the relationship between the calcium-leaching degradation of concrete materials and the structural behaviour of concrete members has yet to be thoroughly established. In this research, to understand the structural behaviour of calcium-leaching concrete, we investigate not only the compressive behaviour of calcium-leached concrete specimens but also the flexural behaviour of the reinforced-concrete (RC) member damaged by leaching attack. Also, the results from experiments were compared with those obtained from non-linear finite-element modelling analysis. The results indicate that calcium-leaching degradation decreases the compressive strength and that compressive behaviour evolves from a brittle to a ductile failure pattern during the calcium-leaching degradation process. The residual strength ranges from 10 to 24% when the leaching/degradation ratio exceeds 90%. The load capacity and flexible rigidity of a degraded RC member decrease when the degradation level increases, in the compressive zone. And the curvature of a leached member increases compared to that of a sound RC member. Additionally, it was found that the values from non-linear finite-element modelling analysis, following the Concrete Damaged Plasticity model in Abaqus, coincided well with the experimental results.