Use of iodine for improving phase quantification using x-ray tomography

Abstract

X-ray computed tomography (CT) has been used to quantify pore structure and crack characterization in cementitious materials. However, similar contrast (greyscale values) of the hydration products in the reconstructed image volume has limited the ability to quantify these phases, and this remains a significant need to further the impact of this experimental method. The goal of this research was to improve the ability to quantify synthesized hydration products by incorporating a contrast agent to improve segmentation between the four main hydration products in portland cement; C-S-H, calcium hydroxide (CH), monosulfate (AFm), and ettringite (AFt). Pure C-S-H, CH, and AFt, and a pure and modified AFm, with iodine as a contrast agent, were synthesized for investigation by x-ray CT. Multi-energy scans were used to isolate individual phases using a synchrotron radiation facility. Using iodine as a contrast agent resulted in accurate quantification of the four main hydration products.