Numerical simulations study of concrete mix proportion based on fluidity

Abstract

Fresh concrete particle packing varies with the composition ratio of the raw materials, and the fluidity changes as a result. The variation in fluidity enhances the complexity of the mix proportion quantitative design, thereby affecting the workability of the concrete. In order to establish the relationship between the mix proportion design parameters and the fluidity, fresh concrete is regarded as a four-level particle size packing consisting of coarse aggregate, fine aggregate, cement and water. Therefore, the dry particle packing theory was extended to the wet particle packing theory, and a physical model for the particle packing of fresh concrete was established. By introducing parameters such as the surplus water consumption, the surplus cement paste and the surplus mortar, a mathematical model for the particle packing of fresh concrete was established. On this basis, the effects of water-cement ratio and water consumption on slump and fluidity were tested under conditions with and without the addition of water-reducing agents, and a functional relationship between slump and water-cement ratio and water consumption was established, which enables the prediction of water consumption at different water-cement ratios and slumps. Furthermore, by establishing the functional relationship between the surplus mortar and the surplus cement paste and the sand to aggregate ratio, the optimal sand to aggregate ratio was functionally predicted. The above research results have enhanced the theory of concrete mix proportion design and assisted in the quantitative design of concrete mix proportion.