This paper describes an experimental study on patch-repaired reinforced concrete columns subjected to axial loads until failure. The behaviour of four series of columns repaired with Class R3 and R4 cement-based mortar was analysed both with and without a bonding agent. The results obtained were compared with control series of undamaged and damaged but unrepaired columns to determine the effectiveness of the repairs and the subsequent improvement in the behaviour of the columns. The results of this study were compared with those of previous work by the authors on the analysis of all-four-side repairs and one-side repairs. The conclusion reached was that patch repairs are highly effective as compared to the other techniques studied and that using Class R3 mortar achieves better results on damaged columns made with low-quality concrete. It was also concluded that applying a bonding agent does not improve the results, although this element was found to be necessary to prevent the premature detachment of the repair when there is a substantial difference between the stiffness of the column concrete and that of the mortar used in the repairs.

This paper describes and analyses the results of an experimental programme carried out at the Universitat Politècnica de València on 18 reinforced concrete (RC) columns, 12 of which had been repaired on one side with cement-based mortar before being subjected to axial loading until failure. The objective of the research was to determine the performance of the columns that had been repaired using different mortars, evaluate the influence of Class R3 and R4 mortar used and of the application of a binder or bonding agent. The results obtained were compared with those of the undamaged control columns and those of the unrepaired damaged columns to obtain values for the efficiency of the repairs and for the improvement in the load-bearing capacity of the columns. The results obtained indicate that the columns repaired with Class R3 mortar, with a lower elasticity modulus, function in better way than the Class R4 repaired ones. The presence or absence of a binder was not found to be a determining factor in improving the behaviour of the repaired elements. The chief novelty of the study lies in the fact that it is the first experimental study on RC columns totally repaired on one side only, using different types of mortar with and without the application of a binder.

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