Effects of Concrete Grades on Strength Characteristics of Reinforced Concrete Slender Beams

This paper presents the results of experimental study on the effects of concrete grades on strength characteristics of reinforced concrete slender beams. The materials used for the concrete were sand, crushed granite, stone dust, cement and water. Concrete mix ratios of 1:2:4 and 1:3:6 by weight with water-cement ratio of 0.6 was used. Four (4) reinforced concrete slender beams were cast, which were loaded with a point load at the beam centre. The results of the work show that, with decrease in concrete grade, there was corresponding decrease in ultimate load and shear capacity. For a drop of 16.67%, 38.67% and 62% in concrete grade there were corresponding decrease in the strength characteristics of beams by about 10.5%, 21.79% and 32.75% respectively. Therefore, decrease in concrete grade does not have the same percentage decrease in the strength characteristics of beams. Also, the mode of failure of reinforced concrete beams, depends not only on the ratio of the span to height of beam and the percentage area of reinforcement provided, but also on the concrete grade.

Keywords
Concrete grades; slender beam; compressive strength; ultimate load; shear capacity