Effect of Treatment of Sisal Fiber on Morphology, Mechanical Properties and Fiber-Cement Bond Strength

Abstract:

The dimensional instability of vegetable fibers due to hygroscopicity results in a gradual loss of adherence in cement based composites which, when in service, are submitted to a natural variation of humidity. Such an effect reduces the contribution of the fiber as a reinforcement and can cause the early rupture of the material. In this work, a treatment of the sisal fibers is performed with the applying of wetting-drying cycles in order to alter their crystalline structure and improve the dimensional stability of the fiber to withstand the variation of humidity: 6, 10, 20, 30 and 34 cycles were applied in order to evaluate the effect on the properties of fiber; a tensile test, the morphological characterization (MEV) and the evaluation of the chemical structure of fiber were carried out. The effect of the treatment on fiber-matrix behavior was evaluated using the pull-out test. Embedded lengths of 16, 20, 30, 40 and 44 mm were defined through a factorial design and used in the test. It is verified that the use of 10 wetting-drying cycles causes less damage to the tensile strength and the elastic modulus of the fiber and contributes to a better adherence with the matrix, with an increase of up to 23 % compared with the untreated fiber. The statistical analysis of the interaction effect between the studied factors, using 2^K factorial design with central composite design, indicates that the number of cycles can be decreased when using a longer length of the embedded fiber.Keywords: wetting-drying cycles, pull out test, tensile strength..

• Periodical: Key Engineering Materials (Volume 634)
• Pages: 410-420
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.634.410
• Online since: December 2014
• Authors: Rogério de Jesus Santos, Paulo Roberto Lopes Lima
• Keywords: Pull out Test, Tensile Strength, Wetting-Drying Cycles

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