Portland cement is the primary binding ingredient used in the creation of concrete, which is one of the factors thought to be one of the main causes of global warming. Several alternatives have been proposed to reduce the environmental impact of concrete manufacturing as it has been found that the cement industry is responsible for about 8% of global CO2 emission. In recent years, alkali-activated binder, a new environmentally friendly inorganic binder made by activating alumino-silicate source material with an alkaline solution, has gained a lot of attention as a viable alternative to Portland cement. Despite the fact that a good assessment of the mechanical properties of geopolymer concrete (GPC) is required for the appropriate design of concrete structural members and the retrofitting of ordinary Portland concrete structures, there are few test results available in the literature. The current study aimed to provide essential information for future development and understanding of the mechanical properties and behavior of GPC as a retrofitting material for reinforced concrete deteriorated structures. The fresh and hardened state properties of both Portland cement concrete and GPC include slump loss, compressive strength (fc), flexural strength (fr), tensile strength (ft), modulus of elasticity (E), stress-strain relationship, bond strength with RFT bars, drying shrinkage, coefficient of thermal expansion tests were performed. The microstructure was also examined. The mechanical results achieved for GPC validated its potential as a high-performance repair material suitable for damaged concrete structures.