Transmission micro-focus X-ray radiographic measurements towards in-situ tracing capillary imbibition fronts and paths in ultra-thin concrete slices

In the present study, we attempted to trace the imbibition fronts and paths in concrete by controlling specimen dimensions and imbibition liquids in transmission microfocus X-ray radiographic tests. Ultra-thin concrete specimens were specifically prepared for 2D imbibitions. CsCl was used as the agent to enhance X-ray attenuation. SEM/BSE/EDS tests were used to measure the micro morphology and element distributions at local sites. Results show that the designed experiments enable the acquisition of X-ray attenuation images with the enhanced contrast, which helps identify the capillary imbibition paths and fronts in the concrete. Liquid is more likely to penetrate through the interfacial transition zone and highly porous cement paste. CsCl solution also increases the contrast gradient of BSE images. Cs and Cl gradually distribute across the imbibition fronts. The proposed measurements offer a way to instantly, continually and visually probe capillary imbibitions in concrete and other porous materials.

Automated summary

The study aimed to trace imbibition fronts and paths in concrete using transmission microfocus X-ray radiographic tests, with CsCl enhancing X-ray attenuation. Results showed designed experiments enable acquisition of X-ray attenuation images with enhanced contrast, aiding in identifying capillary imbibition paths. Liquid was found to penetrate through the interfacial transition zone and highly porous cement paste more easily.