Ultra-High Performance - Fiber Reinforced Cementitious Composites (UHP-FRCC) show excellent mechanical performances, and therefore can be effectively used to retrofit concrete structures. Similarly to the traditional Reinforced Concrete (RC) jacketing, also when a layer of UHP-FRCC is applied on an existing column a sort of confinement can be obtained. Accordingly, the purpose of this study is to investigate the performances of plain concrete cylinders, confined by UHP-FRCC and subjected to uniaxial compression. In some of the layers, high volume fly ash has also been used to replace part of the cement and reduce the environmental impact. As a result, the compressive strength of the concrete core can be enhanced by the presence of UHP-FRCC layer, but when partially using fly-ash, the confinement effect of the jacket reduced. To determine the best solution among the different proposed options, the eco-mechanical analysis was also carried out.