Pultruded GFRP Reinforcing Bars Using Nanomodified Vinyl Ester

Glass fiber-reinforced polymer (GFRP) reinforcing bars have relatively low shear strength, which limits their possible use in civil infrastructure applications with high shear demand, such as concrete reinforcing dowels. We suggest that the horizontal shear strength of GFRP bars can be significantly...

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Bibliographic Details
Published in:Materials 2020-12, Vol.13 (24), p.5710
Main Authors: Vemuganti, Shreya, Chennareddy, Rahulreddy, Riad, Amr, Taha, Mahmoud M Reda
Format: Article
Language:English
Subjects:
Bars
Carbon
Chemical bonds
Composite materials
Concrete
Corrosion
Electron micrographs
Fiber reinforced polymers
Fiber volume fraction
Fourier transforms
Glass fiber reinforced plastics
Impact strength
Infrastructure
Mechanical properties
Multi wall carbon nanotubes
Nanocomposites
Nanomaterials
Polymers
Pultrusion
Rebar
Resins
Shear strength
Shear tests
Tensile strength
Vinyl ester resins
Viscosity
Viscosity measurement
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Summary:Glass fiber-reinforced polymer (GFRP) reinforcing bars have relatively low shear strength, which limits their possible use in civil infrastructure applications with high shear demand, such as concrete reinforcing dowels. We suggest that the horizontal shear strength of GFRP bars can be significantly improved by nanomodification of the vinyl ester resin prior to pultrusion. The optimal content of functionalized multiwalled carbon nanotubes (MWCNTs) well dispersed into the vinyl ester resin was determined using viscosity measurements and scanning electron micrographs. Longitudinal tension and short beam shear tests were conducted to determine the horizontal shear strength of the nanomodified GFRP reinforcing bars. While the tensile strength of the GFRP reinforcing bars was improved by 20%, the horizontal shear strength of the bars was improved by 111% compared with the shear strength of neat GFRP bars pultruded using the same settings. Of special interest is the absence of the typical broom failure observed in GFRP when MWCNTs were used. Differential scanning calorimetry measurements and fiber volume fraction confirmed the quality of the new pultruded GFRP bars. Fourier-transform infrared (FTIR) measurements demonstrated the formation of carboxyl stretching in nanomodified GFRP bars, indicating the formation of a new chemical bond. The new pultrusion process using nanomodified vinyl ester enables expanding the use of GFRP reinforcing bars in civil infrastructure applications.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma13245710