Application of non-destructive integrated CT-XRD method to investigate alteration of cementitious materials subjected to high temperature and pure water

In order to analyze the alteration mechanism after the exposure to various maximum temperatures and immersion in pure water, non-destructive integrated CT-XRD method (the CT-XRD) was applied. Firstly, the verification of the CT-XRD was carried out to compare with conventional powder X-ray diffraction. It revealed that the CT-XRD could evaluate the crystals properly with a given limitation for low energy band. Besides, the CT-XRD indicated the advantage that can detect the presence of crystals which cannot be detected after grinding in preparing the powder sample for the conventional powder XRD. Then, the carbonated cement paste that was heated at 200, 400, 600, and 800 degrees C followed by immersion in pure water was evaluated by the CT-XRD. The results suggest that sample heated at 400 degrees C showed the resistance of leaching at most. In addition, rehydration of clinker minerals generated due to heating at 800 degrees C could be identified although the hydration product was easily dissolved into water. (C) 2019 Elsevier Ltd. All rights reserved.