Fabrication and characterization of metakaolin-based geopolymer composites reinforced with cellulose nanofibrils

Abstract In this work, nanocellulose/geopolymer composites were successfully fabricated through mixing an ultrasonically dispersed suspension of cellulose nanofibrils (CNF) with a metakaolin-based geopolymer (GP) binder. Fresh and hardened state properties of geopolymer composites containing 0.025, 0.05, 0.1, and 0.25 wt% CNF were investigated. The results showed that cellulose nanofibrils can be effectively used as a reinforcing phase of geopolymers, providing a significant increase in the tensile strength. With an increase in the content of cellulose nanofibrils, the consistency of the mixture changes dramatically, becoming viscous, impairing its workability and limiting the incorporation of larger CNF dosages. Therefore, in order to realize the full cellulose nanofibrils reinforcing potential, it is necessary to provide further optimization of the composition of CNF/GP composites, in particular through the addition of plasticizers and/or regulation of water-to-solids ratios.