Comparative Structural Response of Self Consolidating and Traditional Vibrated Concrete Beams

Abstract

Concrete is a very popular artificial material on earth and it is one of the most used construction material in building technology. It is a mixture of three basic elements: water, aggregate and a binder such as cement in various proportions. Modern day concrete is expected to be cost effective while having an acceptable compressive strength, high durability, and high workability. Concrete structural components exist in different forms such as beams, slabs, columns; and the understanding of the response of these components during loading is important for the construction of an overall efficient and safe structure. The aim of this research was to investigate and compare the structural behavior of self-consolidating reinforced concrete beams and traditional vibrated reinforced concrete beams; and to make recommendations to design engineers as to when it will be preferable to use either of the two based on an expected mode of failure. Initially, self-consolidating concrete (SCC) and traditional vibrated concrete mixes of normal strength (30 MPa) were designed. Self-compatibility tests were carried out on the self-consolidating concrete (SCC) mix and workability tests on the traditional vibrated concrete (TVC) mix. Compressive and tensile strength tests were also carried out on cubes and cylinders made from the mixes. When comparability was achieved between both mixes, twenty four steel reinforced beams of variable lengths were cast using both mixes. The load-deformation characteristics of reinforced concrete beams made from the two concrete types were then determined by testing for failure under bending and shear loading and the responses of the two categories of beams were compared with each other and with theoretical expectations. ix The most significant differences between the two mixes were based on workability and slump. Slump test results for the TVC were at an average of 90mm while slump flow test results for SCC were at an average of 700mm. The SCC was more workable and required lesser amount of work to achieve full compaction. Compressive and tensile strength results support the expectation that different mixture proportions can be used to attain comparable strengths. The results of the experimental work revealed comparable strengths of beam specimens made with SCC and TVC. The strengths in SCC were found to be higher though the variations in the experimental values between the SCC and the TVC beams were minor, leading to the conclusion that the high flowability of SCC has little effect on the flexural and shear strengths of concrete members. SCC therefore performs just as well as or may even be better than TVC.