Behaviour of Ferrocement Encased RC columns under concentric Loading

Abstract

In recent years, composite materials have gained significant attention for upgrading and rehabilitating concrete structures. Among the various strengthening methods, ferrocement jacketing has emerged as an effective solution for improving the performance of reinforced concrete columns. Since columns are the primary load-carrying elements in framed structures, any failure in these members can seriously affect the overall stability of the building and may even result in structural collapse. The present research examines the effectiveness of ferrocement jacketing in enhancing the strength of both square and circular reinforced concrete columns. For square columns, two strengthening strategies were investigated. The first method involved providing reinforcement at all column corners, while the second focused on minimizing stress concentration by converting sharp edges into rounded corners. These approaches were further studied using two different jacketing configurations: (i) ferrocement jackets consisting of three wire mesh layers and (ii) jackets with a single mesh layer supplemented by two additional mesh layers at the corners. For circular columns, the study evaluated the influence of varying confinement levels through the use of different numbers of galvanized iron wire mesh layers. The specimens were wrapped with single-layer, double-layer, and triple-layer ferrocement jackets to assess their effect on compressive strength enhancement. A total of 27 specimens were prepared for the experimental program, including 15 square columns and 12 circular columns. After an initial curing period of seven days, the columns were retrofitted with ferrocement jackets and then cured for an additional 28 days. Once curing was completed, all specimens were subjected to concentric axial compression testing to determine their load-carrying capacities. The experimental findings demonstrated a considerable improvement in structural performance due to ferrocement confinement. Square columns with rounded corners and three-layer ferrocement jacketing exhibited the highest enhancement, achieving an increase in load capacity of up to 82.29%. Likewise, the strengthened specimens identified as RFCS, RFCSC, and RFCRCC showed increases in capacity of 68.01%, 53.13%, and 58.20%, respectively. In the case of circular columns, the specimens CC1, CC2, and CC3 recorded improvements of 46.50%, 73.66%, and 132.51%, respectively, indicating that greater confinement through additional mesh layers significantly enhanced compressive strength.