Is scratch test proper to characterize microstructure and mechanical properties of cement-based materials? The effects of loading level and routine

Abstract

Microstructure and mechanical properties of cement-based materials (CBMs) are vitally important for their applications in engineering fields, while the characterizing methods remain to be advanced. Cube-corner scratches were performed to explore the hardness of a hardened cement paste (HCP) with the consideration of multi-scale microstructure. Specifically, we focused on the effects of loading level and routine on the scratch results. Results show that scratch profiles are sensitive to hardness of local phases but fail to detect pores because pore profiles belong to surface roughness. Low-level and slow loads can measure more phases of the HCP while high-level loads are more likely to get the homogenized properties over a large domain. Stress intensity factor by the cube-corner scratches converges rapidly to a narrow range close to the literature. This work improves the understandings in the methodology of scratch test for characterizing the microstructure and mechanical properties of CBMs.