Abstract
AbstractIn this study, the effects of polyvinyl alcohol (PVA) fiber content and nano-SiO2 (NS) on bending resistance of cementitious composites were investigated including bending strength and toughness. PVA fiber contents from 0.6% to 1.5% were added in the composites. The NS contents was 0% and 2% by mass. The water to binder ratio (w/b) was 0.38 for all composites. The specimens were cured for 28 days under 20∘C and relative humidity of 95% before bending test. The results show that the bending strength was improved with PVA fiber content increasing and the maximum bending strength was obtained at PVA fiber content of 1.5%. Although PVA fiber increased bending resistance regardless of NS addition, the optimal content was 1.2%. When the fiber content was less than 1.2%, the bending resistance of cementitious composites increased with fiber content. However, the toughness began to decrease as PVA fiber content increased from 1.2 % to 1.5%.2% NS addition decreased both bending strength and toughness due to the fact that NS was prone to self-desiccation and flock together, resulting in micro crack and strength loss.
Highlights
The biggest challenges of traditional cementitious compositesare low ductility and high fracture risk which have brought many limitations in their structural applica-a large number of studies have pointed that polyvinyl alcohol (PVA) fibers can be pulled out under bending due to low bond strength between matrix and fibers which weakens its bridging effect
The results show that the bending strength was improved with PVA fiber content increasing and the maximum bending strength was obtained at PVA fiber content of 1.5%
When the fiber content was less than 1.2%, the bending resistance of cementitious composites increased with fiber content
Summary
The biggest challenges of traditional cementitious compositesare low ductility and high fracture risk which have brought many limitations in their structural applica-. A large number of studies have pointed that PVA fibers can be pulled out under bending due to low bond strength between matrix and fibers which weakens its bridging effect. For the cementitious composites containing fly ash, low reaction rate of fly ash hurt the interfacial bond strength between cementitious matrix and PVA fibers [21]. The failure mode of fibers under bending load consists of pullout with slight abrasion, surface abrasion and a partially peeled end [22]. Composition (%) Cement Fly ash SiO2 21.05 52.12 Al2O3 5.28 17.86 Fe2O3 2.57 6.57 Na2O 0.17 2.38 K2O 0.58 2.05 SO3 2.39 0.23 Specific gravity
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