Development of lightweight concrete for median barrier applications

Abstract

This study presents the development of a lightweight concrete for median barrier applications as the first step of a three-step project to develop a lightweight concrete median barrier. The present works consists of two stages. In the first stage, bottom ash, one of the by-products of thermoelectric power plants, was used as a lightweight aggregate. The flow characteristics of cement mortar with bottom ash and the effects of aggregate type and size on concrete density and compressive strength were investigated. The effects of incorporating steel and polypropylene fibers were also investigated. According to the results obtained in the first stage, bottom ash for coarse aggregate is not appropriate. However, using bottom ash as a fine aggregate could improve the mechanical properties of the concrete. Thus, in the second stage of the development of lightweight concrete, an artificial lightweight aggregate was used for coarse and fine aggregates and bottom ash was used only as a fine aggregate. In this stage, metakaolin was used to improve the mechanical properties of the developed lightweight concrete. In relation to this, the effects of metakaolin on the workability, density, compressive strength, and modulus of elasticity of concrete were investigated. Finally, two mix proportions were selected for application to a concrete median barrier. The compressive strength and density of the developed concrete are approximately 30MPa and $1700 kg/m^3$, respectively. In further research, a mock-up test will be conducted as the second step in the development of a lightweight concrete median barrier, and in the third step, a computational simulation of a vehicle crash test using LS-DYNA will be performed.