This research aims to shed light on the effect of steel fiber shape, length, diameter, and aspect ratio on the mechanical properties of slurry infiltration fiber reinforced concrete (SIFCON). This study comprised of casting and testing three groups of SIFCON specimens with 6% fiber volume fraction. The first group was reinforced with micro steel fiber, other reinforced by hook end steel fibers, while the last group of specimens reinforced by mixing two shape of steel fiber as hybrid fiber (3% micro steel fiber +3% hook end steel fiber). Silica fume was used as a partial replacement (10%) by weight of cement. 3.7% super plasticizer was used to make the slurry liquid enough to penetrate through the fiber network, while the w/c ratio kept constant at 0.33. It was found from the results achieved that the compressive strength, static modulus of elasticity, splitting tensile strength and toughness are extremely affected by the geometry of fibers because the network of fibers formed and their density depends on the size and shape of fibers. Where the values of micro steel fibers are far outweighing the values of hooked end fibers. It was also deduced from empiricism results that combining long and short fibers gives excellent results.

This study includes detailed information on the mechanical characteristics of the hardened concrete mix for normal concrete (NSC) and reactive powder concrete (RPC) after exposure to crude oil products. Two types of crude oil products (kerosene and gas oil) were investigated after exposure for a period of 180 days. The experimental program consisted of three sets of NSC and RPC specimens; after curing all concrete specimens for 28 days and 2 days to dry in the air, the first set of specimens was immersed in kerosene for 180 days and the second set was immersed in gas oil for the same age, while the third set was left in the air as a reference set (cured normally for 28 days and tested at the age of 180 days). The results showed that the mechanical characteristics of the RPC mix were not highly affected after exposure to each type of crude oil products, where it lost about (3.41–6.32 %) compared with reference RPC mix. While the NSC mix lost about (13.82–21.95 %) of its mechanical characteristics compared with reference NSC mix after exposure to crude oil products for the same period.

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An experimental study was conducted to evaluate the efficiency of patch repair to rehabilitate corrosion-defected reinforced concrete (RC) beam-column members when exposed to bending moments and axial forces. Ten RC beam-column members were tested under combined constant axial force and four-point transverse load up to failure. Two levels of the constant axial force were applied at either 15 kN or 30 kN (i.e., 25% or 50% of the ultimate design load of the control specimen). The accelerated corrosion process was used to get steel reinforcement corrosion inside the concrete of three levels, 0% and approximately 5% and 20%, according to Faraday’s law. The patch repair technique of cleaning or replacing corroded steel bars and replacing the damaged concrete cover with new mortar was used in this study. The experimental results of the corrosion-defected specimens showed a significant deterioration in the structural performance and the integrity by reducing ultimate capacity, stiffness, serviceability, and ductility. Additionally, the effect of increasing axial force was recorded clearly by reducing the adverse effect of corrosion, especially for defected specimens with high corrosion level. The deterioration of corrosion reinforcement could be overcome when using a patch repair technique, which restored the undamaged state and was shown clearly by using a patch repair technique with replacing corroded steel bars.