Condition assessment of microstructure and moisture distribution in mineral building materials by micro X-ray computed tomography

The knowledge of microstructure and moisture condition in capillary porous building materials is essential for building climate control and building durability. The 3D X-ray computed tomography (3D-CT) opens up new vistas for the visualization of both parameters. In this article the performance of this innovative non-destructive testing method is demonstrated by means of two studies showing its feasibility. The first feasibility study was carried out with a drilling core taken from a fair-faced concrete cladding which was strongly damaged by freeze-thaw cycling. The 3D-CT investigations have shown that it is possible to visualize the crack and moisture distribution especially interesting besides the spatial distribution of aggregates and hardened cement paste. So the method opens up new vistas for the tracing of interactions between cracks due to frost and moisture distribution without any destructive interventions. This can help to clarify the damage mechanisms in concrete due to frost which are partly not sufficient known up to now Objective of the second feasibility study was to demonstrate not only the spatial but also the temporal distribution of the moisture in tuff during the capillary water absorption test The 3D-CT investigations have shown that the spatial motion of the capillary moisture front with delayed water absorption of pumice, a magmatic tuff component, can be visualized. Based on these studies this article finally shows the next steps which are necessary to improve the performance of the test method.