Load capacity and chloride resistance of circular concrete columns with repair mortars

Abstract

An experimental investigation was conducted to evaluate the structural behavior and chloride penetration characteristic of reinforced concrete columns to which patch repair was applied. A total of 24 reinforced concrete columns were fabricated. Four repair materials, with different types and contents of admixtures, were selected. The contents of the three admixtures (silica fume, zeolite, and polymer dispersion) were 0%, 10%, and 15%, based on the weights of the admixture and cement. For the experimental methods, a chloride penetration test and an axial compression test were used. As a result of the experiments, compression failure occurred in the control column. For the repaired columns, however, interfacial failure was observed, as the concrete core and repair material were debonded. The repair material that showed the greatest effect was mortar, for which polymer dispersion was used as the admixture. The ultimate strength and the strain at ultimate strength of the column that was repaired with this mortar increased by 40% and 80%, respectively, compared to the control column. Furthermore, the repair mortars that were mixed with the admixture showed much lower chloride concentrations than the control column. In particular, the chloride concentration of the mortar that was mixed with 15% polymer dispersion decreased by 95%, in the section with a depth of 20–30 mm from the column surface.