Effects of alkali-treated kenaf fiber on environmentally friendly geopolymer-kenaf composites: Black liquid as the regenerated activator of the geopolymer

Abstract

Interfacial compatibility enhanced by alkali-treated fiber is the key to the geopolymer-fiber composites (GFCs). However, applications of natural fibers in the GFCs are greatly limited by the black liquid pollution and weak compatibility between geopolymer and natural fibers after alkali-treatment. In this study, the improved compatibility, flexural strength (increased by 69.1%), toughness (increased by 473%), and ductile failure mode of the GFCs were obtained by CaCl2 solution (1 mol/L) immerged into the alkali-treated kenaf fiber and black liquid recycled as a regenerated activator. This outcome could be served as a basis for the low-cost and eco-friendly preparations of the GFCs.