Date of Award

5-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Civil Engineering

Advisor

Ross, Brandon

Committee Member

Nielson , Bryant

Committee Member

Pang , Weichiang

Abstract

Kenaf (Hibiscus cannabinus L.) is an annual fiber plant that is kin to cotton and okra and native to east-central Africa, though it is currently grown in numerous locations around the globe. The plant's apparent high strength and light weight along with its environmental and sustainability advantages makes it a good candidate for use in structural materials. The goal of this study was to design a kenaf product that resembled parallel strand lumber and required minimal processing of the kenaf. The mechanical properties of the two main components of kenaf, the bast fibers and the core, were evaluated using experimental techniques. To supplement components testing, nine 1.2 in. x 2.3 in. x 12 in. kenaf beams were fabricated using strands of Whitten kenaf and a urea formaldehyde resin. The beams were loaded to failure in 3-point bending to characterize strength and stiffness. The kenaf beams had an average bending strength and average horizontal shear strength that were 26.3% and 6.8% respectively of the same properties of southern yellow pine lumber. The average elastic modulus was 7.8% of that of southern yellow pine. A limiting factor of the beams was the fact that the adhesive formed cracks throughout the beams while curing. A linear-elastic analytical model was produced in the form of a calculations spreadsheet to describe the initial load-displacement behavior of the kenaf beams. This model validated the experimental observation that the adhesive did not carry flexural stresses. It also showed that the lower bound strength values found in the component testing correlated with the properties of the materials in the beam. This preliminary study laid the groundwork for future development of whole-stalk kenaf as a structural material. Suggestions for future investigation are discussed at the conclusion of this thesis.

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