The rehabilitation and strengthening of reinforced concrete structures have been attracting increasing attention due to various factors including increase in traffic volume and weight, structural aging and environmental impact. Various techniques such as grouting, guniting and external post-tensioning are being used to retrofit or strengthen deteriorated members. With recent developments in the application of fiber composites in structural engineering, externally bonded Fiber Reinforced Polymer (FRP) system has become one widely used repair techniques because of its durability and long-term cost-effectiveness. In the FRP bonded retrofit technique, epoxy is often used as the bonding material. Because of environmental impact and health issues, construction sector is always looking for sustainable alternative bonding materials for FRP retrofit. A new trend on using Mineral Based Composites (MBC) has garnered the attention for a possible alternative to replace the use of harmful epoxy in FRP retrofit. MBC is formed by mixing the cement with some other minerals together and some concrete admixtures. As a part of a project to investigate optimum mix for the MBC, a series of tests were carried out to study the effect of fly ash content in the MBC mix as a partial replacement of cement. This paper discusses the results from this experimental program and evaluates the optimum fly ash content for the MBC and its associated properties.