Monotonic behavior of reinforced concrete columns confined with high-performance ferrocement

In this study, a method of strengthening circular columns using high-performance ferrocement (HPF) is proposed. This is achieved by replacing the concrete cover by HPF (i.e., comprising rendering material and wire mesh). Direct tensile tests were carried out on HPF specimens. For rendering material with high tensile strength, it is necessary to incorporate its tensile strength in the estimation of the tensile strength of HPF. Nineteen full-scale circular plain or RC columns were tested under monotonic compression. Eleven were detailed with a volumetric ratio of transverse reinforcement ρs at 0.230%. HPF, having three different rendering materials and with one or three layers of wire mesh, was used to confine eight of these columns. Test variables included volume fraction of wire mesh and tensile strength of rendering material. Plain-concrete columns strengthened with HPF have peak strengths at 30-59% higher than control specimens. RC columns having a low ρs at 0.230% and strengthened with HPF can achieve peak strengths comparable with columns having a high ρs at 0.918%. A set of empirical equations for predicting the peak strength of plain-concrete or RC columns strengthened with HPF is derived, showing good agreement with the test data. Lastly, a design procedure for strengthening a RC column by replacing the concrete cover using HPF is proposed.