Physico-mechanical properties of geopolymer mortars for repair applications: Impact of binder to sand ratio.

Deterioration of concrete structures made with ordinary portland cement (OPC) as a binder is inevitable, and this requires repair or rehabilitation using appropriate repair materials. A strong and highly adhesive repair material is very important in order to ascertain the safety of damaged concrete structures. The existing repair materials, especially those that utilized conventional OPC-based materials, appear to require a certain curing condition, which prior studies have revealed to result in a weak link between the repair material and the repaired structures. Hence, an alternative material which is geopolymer mortar was utilized in this study as a repair material, and the impact of geopolymer mortars with various binder-to-sand ratios was evaluated. The physical and mechanical properties of the geopolymer mortars were assessed in addition to their performance as a repair material in terms of their bonding characteristics to conventional concrete. Findings from this study revealed that geopolymer mortar with a binder-to-sand ratio of 1:2 exhibited the highest bonding strength. In addition, geopolymer mortars with a binder-to-sand ratio of 1:3 to 4:1 exhibited better bonding strength compared to when geopolymer paste was used. • The bonding performance of damaged concrete repaired with FA-based geopolymer mortar is still limited. • Binder to sand ratio has been identified to have significant effects on the repaired concrete. • The bonding mechanism of geopolymer repair mortar for damaged concrete is rarely discussed, despite its importance in concrete repair. [ABSTRACT FROM AUTHOR]