Simulation of the Flowability of Fresh Concrete by Discrete Element Method

Abstract

The discrete element method (DEM) was used to establish the slump model and J-Ring model of concrete to describe the flow behavior in the slump test and J-Ring test. Then, the contact parameters of particle-particle and particle-geometry for the concrete DEM model, including restitution coefficient, rolling friction coefficient, static friction coefficient, and surface energy, were measured. In order to avoid the influence of the shape and size of the aggregate, this paper used high-precision glass spheres as the aggregate of the concrete for meso-calibration test, slump test, and J-Ring test. Comparing the simulation results of DEM model with slump test result, a very high agreement between the initial stage, the rapid flow stage, and the slow flow stage of the slump flow–time curve can be found as well as the final slump and slump flow. Moreover, similar to the slump DEM model, the DEM models of J-Ring test, V-funnel test, and U-channel test were established to study the passing ability and filling ability of concrete with outstanding accuracy. Therefore, the concrete DEM model with contact parameters and JKR model can be adopted to study the flow behavior of the fresh concrete.

Simulation of Motion Behavior of Concrete in Pump Pipe by DEM

“…e test results of critical rolling angle (θ cc ) of B1 concrete are shown in Figure 15. According to the test results of the inclined test in Figure 9, the average surface energy (c) of 9 kinds of concrete was calculated by the method in [43]. e surface energy (c) of A1, A2, A3, B1, B2, B3, C1, C2, and C3 is 0.368 J/m 2 , 0.368 J/m 2 , 0.369 J/m 2 , 0.374 J/m 2 , 0.374 J/m 2 , 0.373 J/m 2 , 0.383 J/m 2 , 0.384 J/m 2 , and 0.383 J/m 2 , respectively.…”

“…In this paper, MP-geometry restitution coefficient (e mg ) was measured with reference to Barrios' test [42]; see Figure 5. MP fell freely from a fixed height H and rebounded to the height of h after colliding with the geometry plate [43]. H and h values were recorded with the high-speed camera.…”

“…e rolling friction coefficient of concrete particle was measured by inclined test [43], as shown in Figure 6. In the CAP-geometry rolling friction coefficient (μ r-cg ) test and MP-geometry rolling friction coefficient (μ r-mg ) test, the same stainless steel plate as the slump plate was used as the inclined plate [44].…”

“…e static friction coefficient of concrete particle was measured by inclined test [43], same as rolling friction coefficient test. Bonding three glass aggregates of the same particle size together can prevent the aggregate from rolling before sliding on the inclined plate [45], as shown in Figure 8.…”

“…In this paper, the cohesion force (F pullout ) between fresh concrete particles was determined by inclined test; see Figure 9. For the calculation process, see [43].…”