Axial performance of RC columns strengthened using SHCC and UHPC jackets reinforced with glass fibre and welded steel mesh

The axial performance of reinforced concrete (RC) columns strengthened using strain-hardening cementitious composite (SHCC) and ultra-high-performance concrete (UHPC) jackets reinforced with glass fibre mesh (GFM) and welded steel mesh (WSM) was investigated. Five groups of RC columns were tested – control columns, deflective columns and columns strengthened with different jacket types (SHCC and UHPC) and mesh reinforcements (glass fibre, welded steel) in one or two layers. Unlike existing studies focusing on fibre-reinforced polymer confinement or single-material jacketing, this work provides the first systematic experimental comparison of SHCC and UHPC jacketing systems. The results showed that defective columns retrofitted with SHCC or UHPC jackets exhibited improvements in ultimate load capacity and ductility compared with unstrengthened defective columns. The WSM provided more effective confinement than the GFM. The use of two mesh reinforcement layers led to higher strength, deformation capacity and energy absorption. The highest increase in ultimate load was observed in the columns with UHPC concrete jacketing with WSM. An empirical model was developed to calculate the ultimate axial load of the strengthened columns.