Test Method of Segregation Resistance of High Fluidity Concrete Based on Numerical Simulation of Dynamic Segregation of Coarse Aggregate

The workability of high fluidity concrete (HFC) also depends on its segregation resistance besides fluidity, and gap-passing ability, etc. Currently, there is a lack of easy, quantitative method for evaluating segregation resistance. Efficient assessment is crucial for construction applications of HFC. This paper aims to propose a simple test method for the segregation resistance of HFC on basis of the J-ring test that has been generally used for evaluating the fluidity and passing ability of HFC. Experiment and numerical simulation of J-ring test were conducted for HFCs with different fluidity and segregation resistance. The fresh concretes were treated as two-phase granular fluids of matrix mortar and coarse aggregate in simulation by a newly developed particle meshless method, called DPMP-MPS. The flow and segregation behaviors of the HFCs during J-ring test under different lifting speeds of slump cone were investigated. The numerical results demonstrate a close correlation between the final flow value to slump value ratio (SF_-J/SL_-J ratio) and the segregation resistances of HFCs. Consequently, the J-ring test can assess the segregation resistance based on the SF_-J/SL_-J ratio. Notably, it emphasizes that, for precise evaluation of HFC workability using the J-ring test, the lifting speed of the slump cone should fall within the range of 10 to 15 cm/s.