Compressive Behaviour of Confined Concrete Using Greener High-Tensile-Strength SHCC Jackets

The implementation of jacketing stands out as a widely adopted approach to strengthen existing concrete structures. The performance of jacketed reinforced concrete columns is significantly influenced by the mechanical properties of the jacketing materials and the interfacial bond between the jacket and the core column. Strain-Hardening Cementitious Composite (SHCC), which is compatible with substrate concrete, can notably improve the performance of concrete structures due to its advantageous tensile characteristics. This study experimentally investigated the uniaxial compressive performance of concrete columns confined with a novel and sustainable jacket made of High-Tensile-Strength SHCC (HTS-SHCC). These innovative jackets were prepared by replacing 40% of Portland cement with limestone calcined clay (LC2). A total of 27 specimens with circular and prismatic geometry were prepared, including 9 control and 18 confined with two different mixes of HTS-SHCC. Each mix featured different fibre phases: 2 vol.% polyethylene (PE) fibres in the first mix, and a combination of 1.5 vol.% PE fibres and 0.5 vol.% steel fibres in the second mix. The peak strength, axial strain, and lateral strain increased by up to 55%, 129%, and 80%, respectively. However, these increases were higher in circular specimens and lower in prismatic specimens. The incorporation of rounded corners for prismatic specimens effectively altered the failure mode, subsequently improving both compressive strength and axial/lateral strain.