Micro-scale characterization of the heterogeneous properties of in-service cement-treated base material

Abstract Compared with ordinary cement concrete, cement-treated base (CTB) material consumes much less cement and water, and its mechanical properties are also significantly different. The macroscopic properties of CTB are determined by microstructure. In order to understand the mechanical performance of in-service CTB, it is of great importance to investigate its microscopic structure and properties. In the study, the microscopic mechanical, structural, and chemical characteristics of the mortar and interfacial transition zone (ITZ) of in-service CTB were investigated through micro-scale characterizations. The results indicated the aggregate-mortar interface of in-service CTB is much weaker than that of concrete. A large number of micro-cracks and micro-pores were distributed in the ITZs and mortar. The micro-scale modulus of ITZ was approximately 85.6% of the modulus of the mortar and showed high variance. More compacted cement paste structure is beneficial to improve the mechanical properties of CTB.