Effect of mixing procedure on the fluidity and mechanical strength of the fly-ash based fiber reinforced cementitious materials.

The ternary cementitious materials of fly ash, cement, and silica fume, mixed with PVA fiber, modified PP fiber and calcium carbonate whisker as the fiber toughening medium, were used to prepare the fly ash-based fiber-reinforced composites, and the effects of the mixing process. including the feeding order and mixing time, on the fluidity and mechanical properties of the composites were investigated. Compared with "wet mix+fiber after mixing". "dry mix+fiber first mixing" is more conducive to the uniform dispersion of cementitious material powders and fibers, and the low resistance during the mixing and high fluidity of the matrix is realized, then the early flexural strength (7d) improved by up to 28.5%. Sufficient dry mixing time provides a good dispersion environment for the composite matrix, which can significantly improve the early flexural strength of the fly ash-based fiber - reinforced materials, but excessive mixing time will weaken the fiber in the matrix, in terms of the dense filling effect and bridging effect, resulting in the reduction of the early flexural strength of the specimens. The best mixing time is 5min of dry mixing, 5min of wet mixing, and finally 6min of full mixing. [ABSTRACT FROM AUTHOR]