Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Civil Engineering

Use of structural lightweight concrete is preferred to reduce the dead load of concrete structures. The lower density of the lightweight concrete decreases the weight of the building. It decreases the earthquake loads, minimizes the sizes of the load bearing structural member and contributes into economical solution of the foundation members. The strength of concrete cubes, cylinder and prisms cast target M30 grade concrete and reinforced with steel and polypropylene fibers were used in concrete matrix to study the shear behavior. Fibers improved the mechanical properties of concrete. The benefits in terms of concrete toughness and shrinkage cracking of a combination of polypropylene and steel fibers are presented. The parameters considered in this research were ratio of lightweight aggregate, ratio of fibers, type of fibers, and type of aggregate.To investigate the effect of there parameters on shear behavior of lightweight concrete beams, a total of 14 beams were tested under four-point loads. The results demonstrated that the effect of addition of steel and polypropylene fiber was more pronounced on the tensile strength of lightweight concrete than the compressive strength of such concrete

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