Discrete element modelling of the uniaxial compression behavior of pervious concrete

Pervious concrete (PC) has been widely used in recent years. With increasing attention on PC, it promotes further understanding of its mechanism responsible for the resulted performance. The objective of this study is to propose a 3D discrete element method (DEM) model to simulate the uniaxial compression process and analyze the meso mechanical properties of PC. The user-defined ellipsoid composed of pebble discrete elements was used to simulate aggregate. In the DEM, the mechanical behaviors of materials were simulated with contact constitutive models of discrete elements. The linear contact model and parallel-bond model were employed to simulate the strength properties between two adjacent aggregates, and between cement paste and aggregate. The parallel-bond parameters were calibrated based on the stress-strain curve obtained from the laboratory test. The reliability of the method was verified by comparing the virtual results with the laboratory tests of PC with 6 groups of different aggregate sizes. It was proved that the DEM model established can be used to simulate the rising section of the stress-strain curve of PC accurately. The maximum absolute error of uniaxial compressive strength is 0.67 MPa, and the relative error is within 5%. By analyzing the number of contact points, the contribution rate of different sizes of aggregates to the contact force and the distribution of the force chain, it can be concluded that the coarse aggregate plays a major role in resisting compression load in PC, while fine aggregate mainly increases the number of contact points to achieve force transmission.