Argon broad ion beam sectioning and high resolution scanning electron microscopy imaging of hydrated alite

Scanning electron microscopy (SEM) imaging is able to visualize micro- to nano-structures of cement and concrete. A prerequisite is that the sample preparation preserves the native structure of the specimen. In this study, argon broad ion beam (BIB) sectioning is compared to state-of-the-art sample preparation (resin embedding, polishing) for hydrated alite. Additionally, it is investigated if during BIB, sample cooling is beneficial to avoid deterioration of cement hydrates. The aim is to quantitatively measure pore size distributions in hardened alite pastes. Therefore, not only optimized sample preparation but also optimized imaging conditions are investigated. Finally, it is demonstrated that by image analysis pores down to a diameter of 5 nm in hydrated alite pastes can be quantitatively analysed.

Automated summary

This study compared argon broad ion beam (BIB) sectioning with state-of-the-art sample preparation methods for hydrated alite in order to quantify pore size distributions in hardened pastes. It investigated the benefits of sample cooling during BIB to avoid deterioration of cement hydrates, and demonstrated the quantitative analysis of pores as small as 5 nm in hydrated alite pastes through image analysis.