Argon Broad Ion beam sectioning and high resolution scanning electron microscopy imaging of hydrated alite

TL;DR

This study compares argon Broad Ion Beam sectioning with traditional methods for SEM imaging of hydrated alite, demonstrating improved preservation and the ability to analyze nanometer-scale pores.

Contribution

It introduces optimized BIB sample preparation and imaging conditions for high-resolution SEM analysis of hydrated alite, enabling quantitative pore size measurement down to 5 nm.

Findings

BIB preserves native microstructure better than traditional polishing.

Cooling during BIB prevents deterioration of cement hydrates.

Pores as small as 5 nm can be quantitatively analyzed.

Abstract

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 phase and 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.