Abstract
The uniaxial tensile properties of multi-scale fiber-reinforced cementitious material (MSFRCM) with steel and polyvinyl alcohol (PVA) fibers and calcium carbonate whisker (CW) were studied. The results showed that CW improved the uniaxial tensile stiffness, strength, peak strain, and toughness of the steel-PVA hybrid fiber-reinforced cementitious material. The CW not only played a role in the small deformation stage but also improved the load holding capacity and toughness of the hybrid fiber-reinforced cementitious material during the large deformation stage. Computational models to assess the uniaxial tensile strength and toughness of the MSFRCM were established. Microstructure observations showed that the steel and PVA fibers formed a weak interfacial transition zone (ITZ) due to the “wall effect.” The CW effectively optimized the structure of the ITZ of the steel and PVA fibers through physical and chemical effects, such as filling, bridging, improving Ca(OH)2 orientation, and chemical effects. The steel fibers, PVA fibers, and CW in the MSFRCM bridged cracks at the macro, mesoscopic, and microscopic levels, respectively. As a result, we observed a fiber chain effect that improved the positive hybrid effect between the multi-scale fibers.
Highlights
The uniaxial tensile properties of multi-scale fiber-reinforced cementitious material (MSFRCM) with steel and polyvinyl alcohol (PVA) fibers and calcium carbonate whisker (CW) were studied
Based on computational formulas found in the literature [9], a computational formula was employed to calculate the uniaxial tensile behavior (TB) of the hybrid fiber-reinforced cementitious material according to Equation [1]:
The CW played a role during the small deformation stage and improved the load holding capacity and toughness of the hybrid fiber-reinforced cementitious materials during the large deformation stage
Summary
The main binder materials consisted of 70 wt.% of ordinary Portland cement and 30 wt.% of fly ash. The fine aggregate consisted of quartz sand, and a polycarboxylic acid superplasticizer (water reducing ratio of 32%) was employed to control the workability of the fresh mixture. Fresh MSFRCM mortars were cast into dog-bone steel molds and vibrated for 60s. The samples were stored in a 20±3 ̊C water tank for 28 days of curing
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