Meso-scale cracking behavior of Cement Treated Base material
Although much attention had been paid to the study of macroscopic performance of Cement Treated Base (CTB), the meso-scale study of this heterogeneous and quasi-brittle material is rather limited. In this paper, a two-dimensional (2D) meso-scale crack propagation model of CTB assumed as a three-phase material composed of aggregate, cement mortar and interface transitional zones (ITZ) was developed through Finite Element method (FEM) with cohesive elements. Digital image processing (DIP) methods and vectorization processing were utilized to create a 2D heterogeneous numerical fracture model using the digital image obtained through scanning. The zero-thickness cohesive elements with traction-separation laws were inserted into both the cement mortar and the aggregate–cement interfaces to simulate the potential micro-crack in the cohesive zone model (CZM). Nano-indentation tests and inverse analysis were employed to determine the material parameters of model. Different cohesive parameters were obtained for the crack propagation of FE models to study the meso-scale material properties. Analysis results showed that the load-displacement curves, crack geometry, and tensile strength based on the numerical simulation agreed with those obtained from laboratory tests.
Keywords: Cement Treated Base (CTB), Finite Element method (FEM), Meso-scale, Semi-Circular Bending (SCB), Nano-indentation, Interface transitional zones (ITZ)