Fig. 11. Corrosion resistance of polyvinyl alcohol fibers (a) erosion by
Cl-;(b) erosion by
SO42-; (c) coordination of polyvinyl
alcohol fiber and Nano-sio2[18]
Reproduced from [18], with permission from [Publisher]
The mixture of mineral particles and fibers can effectively improve the
resistance of geopolymers to chemical erosion. Wang et al.[18]
proved that geopolymer mortars with a polyvinyl alcohol fiber content of
0.6 ~ 0.8 v% and a nano-sio2 content of
1.0 ~ 2.0wt % present better chemical resistance, as
shown in Fig. 11. The incorporation of nano-sio2 and
polyvinyl alcohol fiber has a synergistic effect on the durability of
geopolymer mortar. The bridging effect of polyvinyl alcohol fibers
limits the crack propagation, and nano-sio2 is found conducive to
filling the micropores and improving the microstructure. The addition of
wollastonite, tremolite and basalt fibers to metakaolin base polymers
can also improve sulfate and chloride ion erosion. The mixture with a
ratio of 5% wollastonite, 5% tremolite and 2% basalt fiber sample
possesses the highest compressive strength and the strongest erosion
resistance[72]. If the polymer is prepared using 0.2% polypropylene
fiber and 3% nanoparticles, the durability of the polymer can be
increased by 67%[73]. The addition of basalt fiber to geopolymer
can reduce weight loss after acid erosion and maintain the compressive
strength as much as possible, which indicates the good durability of
basalt fiber reinforced geopolymer[74]. The combination of cellulose
fiber and fly ash can improve the durability of composite materials
under the sulfate dry-wet cycle. In the late cycle, the pore volume
increases obviously, the proportion of small holes decreases, and the
mesopores increase. In this case, the durability of concrete can be
consequently improved by optimizing the ratio to increase the proportion
of harmless holes such as micro holes and small holes[75].