Godwin Dilibe Offiah, M.S

Engineered Cementitious Composites (ECC) are a class of strain-hardening infrastructural materials that exhibit a tensile strain capacity that is non-existent inconventional concrete. This ductility provides advantages over normal brittle concrete such as improved durability and safety. However, ECC relies upon discontinuous, randomly oriented polymer fibers to generate its characteristic distributed microcracking. These petroleum-based fibers require a large amount of energy to be produced and… Show more

Engineered Cementitious Composites (ECC) are a class of strain-hardening infrastructural materials that exhibit a tensile strain capacity that is non-existent inconventional concrete. This ductility provides advantages over normal brittle concrete such as improved durability and safety. However, ECC relies upon discontinuous, randomly oriented polymer fibers to generate its characteristic distributed microcracking. These petroleum-based fibers require a large amount of energy to be produced and are based on a nonrenewable source. The goal of this project is to be able to use natural Curaua vegetable fiber as a substitute for the polymer fibers, while still maintaining the same strain hardening behavior as polymer fiber ECC. This is difficult due to the larger diameter, the lower strength, and the extreme hydrophilicity of the natural fiber as compared to the polymer fiber. This investigation focuses on compositional changes to the cementitious matrix to accommodate these physical property differences of the natural fibers. Experimentally, discontinuous Curaua fiber composites were cast using water content, recycled tire rubber content, and fiber fibrillation as variables to manipulate matrix strength to match the natural fiber properties. The performance was evaluated using uniaxial tensile testing. The addition of recycled rubber and increase water content (from 25% to 28.9% of cementitious material, by weight) lowered matrix strength as intended. However, theses compositional changes did not promote strain-hardening behavior as desired. Fiber fibrillation was expected to improve fiber dispersion and increase the number of crack bridging, however, performance improvements were not seen. This is perhaps due to damage introduced by the fibrillation technique, though further investigation is needed to confirm these speculations. Show less