Experimental modelling of segregation on reinforced concrete beam using a graded concrete approach

Abstract

Segregation is a phenomenon that commonly arises in concrete because concrete is a multiphasic material. The segregation causes the concrete to create non-uniformly distributed along with the height of structural members so that it affects the material characteristics such as strength, stiffness, creep, durability, and structural performance resulting in a higher impact on maintenance costs and shorter structure life. To understand the effect of segregation on the RC beams as flexural elements on experimental works, researchers aim to model the beam underwent segregation using a graded concrete approach. To model this segregated element, a high strength concrete mix will be cast at lower fibre, while a mix of lower concrete strength is positioned at the upper fibre. In rupture stage, the segregated element gained its benefit in load performance due to the greater of the material strength at the bottom fibre. At yield and the ultimate stage, the beam exhibited a decrease in load performance due to the lower concrete strength in the area of neutral axis to the compressive fibre; creating a low resistance in load and stress transfer during the loading. After the yield of tensile rebars, the segregated beam fluctuates in the reading of load and deflection increments towards the ultimate point. With the accumulation of concrete density in the middle to the base of the beam element, interlocking action between the aggregates in the compression fibre has absent. When the beam performs a large curvature, the interlocking force of the material in charge of providing resistance to external forces is drastically reduced.