Investigation of the Bond Behaviour Between Geopolymer TRM and Concrete

Aiming towards sustainability in the construction sector, various alternatives to cement-based materials have been proposed, with geopolymers being an excellent candidate due to their reduced carbon footprint as well as their exceptional mechanical and durability properties. With an increase in the need for external strengthening of structures, the use of textile-reinforced mortars (TRM) has been in the spotlight lately. This study aims to investigate such a strengthening system which uses alternative materials to cement-based matrices. The study focuses on the bond behaviour between textile-reinforced mortar using a binary geopolymer mortar as a matrix and a concrete substrate. A conventional TRM system employing a cement-based matrix was also investigated and used as a reference. The investigative parameters include the type of matrix (geopolymer or cement-based) and the bond length (50, 75, 100, 150 mm). For this purpose, a total of 8 twin specimens were prepared and tested by modified beam test. The results showed that specimens employing the geopolymer mortar achieved higher peak load than their cement-based counterparts regardless of the bond length by 25–94%, while also achieving higher vertical displacement by at least 14%. When geopolymer matrix was used the effective bond length was lower than the cement-based TRM although both systems exhibited the same failure mode.