Quantitative characterization of pore morphology in hardened cement paste via SEM-BSE image analysis

Pore structure is a significant microstructural characteristic in cement-based materials and dominates the mechanical and transport properties of the materials. In this study, sectional plane analysis based on backscattered electron scanning electron microscope (SEM-BSE) images was used to provide insights into the nature of the pore structure. The effects of the w/c ratio on the total porosity and heterogeneity of the local porosity were analyzed. By coupling using Digital Image Processing (DIP) method, each single pore displayed on SEM-BSE images was captured, and the equivalent circular diameter, hydraulic radius, and roundness of each single pore were calculated to describe its size and shape characteristics. The relationship between the pore size and pore shape was also established by comparing the pore size distribution and the shape parameter distributions. Results indicates that pores become less spherical with increasing pore sizes. Status oriented model was further introduced to simulate the hydration process and investigate the forming mechanisms of capillary pores. (C) 2019 Elsevier Ltd. All rights reserved.