A new method for the nuclear magnetic resonance (NMR) surface relaxivity calibration in hydrated cement samples is proposed. This method relies on a combined analysis of 28-d hydrated tricalcium silicate samples by scanning electron microscopy (SEM) image analysis and ¹H-time-domain (TD)-NMR relaxometry. Pore surface and volume data for interhydrate pores are obtained from high resolution SEM images on surfaces obtained by argon broad ion beam sectioning. These data are combined with T₂ relaxation times from ¹H-TD-NMR to calculate the systems surface relaxivity according to the fast exchange model of relaxation. This new method is compared to an alternative method that employs sequential drying to calibrate the systems surface relaxivity.

Burning of clinker is the most influencing step of cement quality during the production process. Appropriate characterization for quality control and decision making is therefore the critical point to maintain a stable production but also for the development of alternative cements. Scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDX) delivers spatially resolved phase and chemical information for cement clinker. This data can be used to quantify phase fractions and chemical composition of identified phases. The contribution aims to provide an overview of phase fraction quantification by semi-automatic phase segmentation using high-resolution backscattered electron (BSE) images and lower-resolved EDX element maps. Therefore, a tool for image analysis was developed that uses state-of-the-art algorithms for pixel-wise image segmentation and labeling in combination with a decision tree that allows searching for specific clinker phases. Results show that this tool can be applied to segment sub-micron scale clinker phases and to get a quantification of all phase fractions. In addition, statistical evaluation of the data is implemented within the tool to reveal whether the imaged area is representative for all clinker phases. This article is protected by copyright. All rights reserved

This study demonstrates the application and combination of multiple imaging techniques (Light Microscopy, Micro X-ray Computer Tomography (μ-CT), Scanning Electron Microscopy (SEM) and Focussed Ion Beam - Nano Tomography (FIB-nT)) to the analysis of the microstructure of hydrated alite across multiple scales. However, by comparing findings with mercury intrusion porosimetry (MIP) it becomes obvious, that the imaged 3D-volumes and 2D-images do not sufficiently overlap at certain scales to allow a continuous quantification of the pore size distribution (PSD). This can be overcome by improving the resolution and increasing the measured volume. Furthermore, results show that the fibrous morphology of Calcium-Silicate-Hydrates (C-S-H) phases is preserved during FIB-nT. This is a requirement for characterisation of nanoscale porosity. Finally, it was proven that the combination of FIB-nT with Energy-Dispersive X-ray Spectroscopy (EDX) data facilitates the phase segmentation of a 11×11×7.7 μm³ volume of hydrated alite. This article is protected by copyright. All rights reserved