Residual capacity and permeability-based damage assessment of concrete in damaged RC columns

An experimental investigation was conducted to evaluate both residual capacity and the damage of the concrete material in previously damaged RC columns. Three circular columns, each caged to provide low, medium, and high level of confinement, were axially loaded to failure. All damaged columns were then cut into three pieces, and two cored cylinders were taken from each piece. The first core was prepared and instrumented for compression, whereas the second was sliced into a number of 25-mm disks for permeability testing. For each column, a comparison was made between the stress-strain relationships of concrete cores, intact concrete cylinders, and confined concrete associated with columns. Results showed an average loss of 68, 42, 33, and 30% in the lateral strain, axial strain, strength, and stiffness of the damaged concrete, respectively. A permeability-based damage profile was established that showed the intensity and extent of damage in the concrete. The study showed a 33% loss in axial strain capacity and a 17% reduction in compressive strength, resulting in a 46% increase in the permeability of the concrete.