الفهرس 
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Abstract
Opening in existing reinforced concrete structures is a common practical problem that is always encountered for various purposes as service ducts, plumbing, air conditioning ducts and sometimes elevators or chimneys.The presence of an opening reduces the overall stiffness of the slab and may lead to decrease in ability of the structure to withstand the imposed loads and the structure needs.
This thesis presents an experimental study on strengthening the reinforced concrete slabs with opening using ferrocement laminates as external overlays, which may be considered a suitable technique to use in developing countries. Twenty one slabs weretested; two specimens were kept as control specimens one of them without opening and the other with central opening, the other nineteen specimens were strengthened with ferrocement laminates. Different parameters were taken into consideration during this study;size, number and location of opening, compressive strength for the mortar matrix, thickness of the ferrocement layer, percentage of wire meshes reinforcement in the ferrocement cover layer, types of wire mesh, strengthening type, strengthening length, and fixation method.
The experimental resultsindicated that R.C. slab with opening gave a reduction of 56% in capacity compared to R.C. slab without opening, the strengthening of slab with central opening using ferrocement resulted in about 126% enhancement in the slab failure load compared to non-strengthened slab with central opening.All the strengthened specimens had higher ultimate loads than the control specimen.It was found increasing number of opening resulted in decreasing ultimateload, ductility, strain energy, and stiffness, the ferrocement thickness has a great influence on the amount of gain in ultimate strength, stiffness, and energy absorption. Using square wire mesh as reinforcement for the ferrocement laminates instead of expanded wire mesh exhibited better performance in ultimate load, ductility, strain energy, and stiffness.
Generally, the results of the strengthened slabs demonstrated that,ferrocement laminates can be successfully used for increasing the ultimate carrying capacity, strength, energy absorption, and stiffness of slab with opening.