Simulating the workability of fresh self-compacting concrete with random polyhedron aggregate based on DEM

Coarse aggregate, as a vital filling material of concrete mixture, plays a role of the skeleton. Both the shape and size of coarse aggregate have a great influence on the workability of fresh concrete. Customarily, aggregates are represented by spherical particles with different sizes in discrete element method. However, the shape of real coarse aggregate is quite random and irregular, because it is produced in different ways, crushing, blasting or naturally rounded. Therefore, spherical particles cannot cover the characteristics of the complex geometrical shape of real coarse aggregate precisely and lead to the limited calculation accuracy. Especially for the simulation of passing ability, the influence of coarse aggregate shape is significant. In order to evaluate the fresh concrete workability comprehensively, a fast and efficient approach to establish irregular shape polyhedron particles used to simulate the real shape coarse aggregate is presented in this paper. To approximate the real state of coarse aggregate, the size and number of coarse aggregate elements are also in accordance with the real gradation in the rheological simulation. A slump-flow test for fresh self-compacting concrete (SCC) is performed to verify the feasibility and validity of the method. And L-box test is taken to assess the passing ability of SCC with this method. The simulation results show good agreement with experimental tests.