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Abstract
The thesis presents an experimental study on the combined effect of using nano silica as cement substitution of concrete and steel fibers on mechanical properties and water permeability of concrete to perform concrete with the best characteristics. A total of twenty mixes were tested in the current study, Nano silica is used as partial cement replacement by 0, 1, 1.5, 2, and 4 wt%, and steel fiber is used as volume substitution by 0, 0.45, 0.9, and 1.35%. Workability test (slump), compressive, splitting, flexural, permeability, modulus of elasticity, and pre and post fire bond strength are investigated in the current study. Microstructures of optimum concrete mixtures were also investigated through scanning electron microscopy (SEM), X- ray diffraction (XRD) and thermo gravimetric analysis (TGA) are provided for detecting changes in hydration material due to the addition of NS and SP. A full factorial design was introduced, and the effects of studied parameters were characterized and analyzed