Fig .4. Effect of fiber content on the compressive strength of
geopolymer (a) little; and (b) much[42]. Reproduced from [42],
with permission from [Publisher]
In short, the strong bond between geopolymer and fiber may be related to
the following aspects: (a) different reaction mechanism and reaction
products of geopolymer and cement-based materials; (b) strong adhesion
of N-A-S-H to matrix; (c) the formation of an improved interface
transition zone (ITZ) in the geopolymer, which is partially attributed
to the fact that cement-based materials tend to form low strength
silicates at the ITZ, and partially that the fiber matrix interface is
affected by higher pH values.
4.2 Flexural strength
Considering the brittleness caused by the internal structure of
geopolymer cross-linked each other, adding fiber can significantly
enhance the flexural properties of geopolymer, while considering the
crack bridging mechanism of fibers, the bending strength of fiber
reinforced geopolymer is significantly higher than that of unreinforced
geopolymer.