Pacheco-Torgal et al. [17] determined the bond strength between concrete substrate and geopolymer mortar produced from tungsten mine waste containing calcium hydroxide and found that the geopolymeric binders had very high bond strength even at early ages compared with that of commercial repair products.
In addition, Songpiriyakij et al. [18] also tested the bond strength between rebar and concrete substrate by using geopolymer
paste as the bonding agent, and reported that the bond strengths of rice husk ash and silica fume geopolymer pastes were
approximately 1.5 times higher than those of comparable repair epoxies. Therefore, the bond strengths of geopolymer materials are sufficiently high and should be used as an alternative bonding material for repair works.