Flexural Behavior of Reinforced Cement Concrete Beams Using Superplasticizer

In the present investigation, the effects of superplaticizer on deflection and cracking of reinforced cement concrete beams were observed. Two variables, namely, grade of concrete and percentage of reinforcement were considered. Conplast-P211 was employed as superplaticizing admixture. Two grades of concrete (M20 and M50) were considered. M20 was considered as normal strength concrete, whereas M50 was considered as high strength concrete. Three different percentages of reinforcements (1.38, 2.47 and 3.89) were adopted. The behaviors of specimens cast with normal strength concrete and high strength concrete were compared with respect to ultimate strength, deflection and cracking. It is noted that the experimentally observed ultimate moments were nearly 1.5 times more than the theoretical ultimate moments. This indicates the degree of safety incorporated in IS code. For high strength concrete beams, deflection reduces, when compared to normal strength concrete beams, at the same load level. Beams having lower percentages of reinforcement were found to deflect more, compared to those having higher percentages of steel at the same load level. There is no significant variation in the number of cracks, crack heights and crack spacing for normal strength concrete beams and high strength concrete beams