Using dental X-ray imaging to measure the diffusion coefficient for concrete samples

The diffusion coefficient (D_ic) is an essential parameter that helps to understand various durability issues in concrete, like corrosion, alkali-silica reaction (ASR), and freeze-thaw damage. However, most research in this area has focused on homogeneous materials like paste and mortar, while concrete has proven to be challenging because of its inhomogeneous nature. This study used dental X-ray equipment adapted for transmission X-ray measurements to measure ion diffusion. This device is named CHIP (Checking Ion Penetration). This work applies the CHIP on 104 paste and 104 concrete samples with hydration times between 45 and 1100 days. This work improved the accuracy by combining measurements from multiple angles and correcting for X-ray beam hardening. This approach improved the accuracy of concrete D_ic measurements by 20% (as indicated by R square) while reducing variability (expressed as the coefficient of variation) by 63%.