The ingress of chloride ions in a harsh chloride environment leads to the corrosion of reinforcing steel bars and reduction in the service life of concrete structures. Prediction of the service life of chloride-exposed concrete structures is strongly dependent on chloride diffusion coefficient, which in turn is influenced by several factors including materials and environmental parameters, binding of chloride ions to the solid phase of concrete, and the stresses caused by external load acting on the structure. The diffusion of chloride in concrete is increased significantly by damage associated with load-induced stress, which, if not taken into account, can lead to erroneous prediction of the service life. This paper investigates the impact of compressive stress-induced damage on chloride transport in concrete. An experimental investigation involving non-steady-state migration test as per NT BUILD 492 was carried out on unloaded concrete specimens damaged under axial compressive load. Numerical si...

In the present study, the economic feasibility of development of 15 MW wind power plant (wind farm) at Taif, Western Province of the Kingdom of Saudi Arabia (K.S.A) has been investigated by analyzing long-term wind speed data. Western province has relatively better wind energy resources. Data analysis indicates that monthly average wind speeds of Taif (21 29’ N, 40 32’ E) range from 3.1 to 4.8 m/s at 10 m height. The wind farms simulated consist of different combinations of 600kW commercial wind machines (50 m hub-height). NREL's (HOMER Energy's) HOMER software has been employed to perform the techno-economic assessment.The study presents monthly variations of wind speed, cumulative frequency distribution (CFD) profiles of wind speed, monthly and yearly amount of energy generated from the 15 MW wind farm (50 m hub-height), cost of generating energy (COE, $/kWh), capacity factor (%), etc. The CFD indicates that the wind speeds are less than 3 m/s for 46% of the time during the year. This implies that wind electric conversion systems (WECS) will not produce energy for about 46% of the time during the year. The annual energy produced by 15 MW wind farm (50 m hub-height) has been found to be 19939 MWh. The cost of wind-based electricity by using 600kW (50m hub-height) commercial WECS has been found to be 0.0576 US$/kWh. With the development of 15 MW wind farm, about 453 tons/year of carbon emissions can be avoided entering into the local atmospheric. The paper also attempts to address various aspects (such as: effect of hub-height, etc.) of wind farm establishmen

Ultra-high performance concrete (UHPC) is a new generation concrete with extremely high tensile and compressive strength, high durability, and ductility. UHPC offers tremendous opportunities for use in new thin and slender structural concrete elements and repair of existing concrete structures and has an excellent potential to replace conventional steel reinforcement in normal concrete (NC) members. This paper investigated the potential application of a hybrid NC-UHPC beam using a thin UHPC layer on the tension face to cater to tensile stresses, eliminating the need for passive steel reinforcement. Four-point flexural load tests were performed on 24 composite beams with a thin UHPC layer overlaid with NC. The parameters considered include the thickness of the UHPC layer, depth, and span of the beam. A linear behavior categorizes the flexural behavior of the hybrid NC-UHPC beam up to the ultimate load, after which the hybrid beam shows a non-brittle failure, and softening ensues associated with cracking, increased deflection, and loss of load resisting capacity. The unfinished top surface of the UHPC layer and the overlying NC developed a full composite action without any slip. It was found that a two-day self-curing of the UHPC layer was found to be essential for the development of a strong bond between the layers. The random dispersion and orientation of steel fibers in the UHPC can lead to a decreased tensile response for larger hybrid NC-UHPC beams. The experimental results validate the potential of hybrid NC-UHPC beams as an attractive, structurally feasible, and alternative sound form of construction in terms of their high flexural strength and corrosion-free service life. The proposed unreinforced hybrid system could be used in the construction of precast beams and slabs for residential as well as industrial buildings. Further research, including full-scale load testing of the hybrid beam, is needed prior to practical applications.