FLEXURAL BEHAVIOR OF STRUCTURAL LIGHTWEIGHT CONCRETE BEAMS

Compressive strength is the most effective mechanical property to produce structural lightweight aggregate concrete, by increasing compressive strength the other mechanical properties such as tensile strength, modulus of elasticity, and flexural strength also increase, it was indicated that the type of lightweight concrete, and the type of lightweight aggregate are the most effective factors on the value of compressive strength, so that structural lightweight aggregate concrete was produced using expanded polystyrene having size less than 4.75 mm as 60% replacement ratio of normal weight fine aggregate (sand)by, cement content 360 Kg/m3, 90 Kg/m3 silica fume was added with 20% replacement ratio of cement by weight, and high range water reducer was used with 2% of cement by weight, and 45% water to cement ratio was used, the experimental work was to determine the compressive strength, tensile strength, and flexural strength of that mix, reinforced concrete beams made from the previous mix were cast and compared with reinforced normal weight concrete beams, lightweight aggregate beams were cast with different shear span to depth ratios (a/d), different reinforcement steel to concrete ratio (µ), different shear einforcement, different cases of loading, once three points of loading, another time four points of loading, the load deflection curve of concrete was drawn using LVDT, and strain gauges were put on the surface of bottom steel bar in order to measure strain in it subsequently draw load-strain curve for steel