Direct three dimensional observation of the microstructure and chemistry of C3S hydration

摘要

Although portland cement has been used for over a hundred years as the binder in concrete, the basic mechanism of hydration is still not well understood. Progress has been halted for the fact that it is challenging for most current experimental techniques to give direct observation of the hydration process in-situ and provide quantitative measurement on the microstructure and chemistry at the nano-length scale. Recent advances of nano scale X-ray imaging make nano-tomography and nano-X-ray fluorescence reality. The nano-scale X-ray beams in these techniques allow the sample to be imaged nondestructively and provide a high transmission of signal that penetrate through both sample materials and a possible solution environment, which could make themselves in-situ techniques. Moreover, these techniques can be combined to enrich both datasets to become a more powerful technique. In this dissertation, the applications of both techniques have been established from micron lab scale experiment to nano-synchrotron investigation for studying cementitious materials. The progresses have been shown from first application on 3D chemical characterization of fly ash particles at the nanoscale to later updated versions of in-situ experiments for studying cement hydration, which allow quantitative measurements on 3D structure, chemistry and mass density of hydration products at different hydration periods. These unprecedented discoveries could lead to a breakthrough for both nanoscale analysis of any material and cement hydration research.