Research progress on cement-based materials by X-ray computed tomography

X-ray computed tomography (CT), as an imaging technique, has played an important role in the area of material characterization in civil engineering during the past 40 years. It has promoted the investigation of materials from the macroscopic testing to the microscopic characterization. Though numerous researches have been done by using X-ray CT technique to investigate the microstructure, the mechanical behavior, and the durability of cement-based materials, there is no comprehensive review on the testing process and the results obtained. Based on the research progress in the past 40 years made on the cement-based materials, the relevant issues to the X-ray CT technique are reviewed in this study in terms of the equipment used, the sample preparation, the test methods, the data processing, and the results obtained. Particularly, this article focuses on assessing microstructure, mechanical behavior, damages from freeze-thaw cycles, carbonation, sulfate attack, alkali-silica reaction, and the quantification of permeability of cement-based materials by using X-ray CT. The results can serve as a guidance for future experimental design of the similar research and provide inspirations on improving equipment for broader applications to cement-based materials.