Direct observation of C3S particles greater than 10 μm during early hydration

4D nanoimaging of early age cement hydration

“…Moreover, μCT is being widely used 23 and in particular to follow in situ 4D (3D + time) some specific features of cement hydration 24 – 33 . In the last three years, important advances have been reported including: i) the automated correction for the movement of suspended particles at very early ages 34 which allowed to follow in situ PC hydration after water mixing 35 ; ii) to follow the fast dissolution of plaster and the precipitation of gypsum 36 ; iii) the simultaneous use of neutron and laboratory X-ray tomographies for in situ studying the microstructural changes of PC mortars on moderate heating 37 ; and iv) the measurement of alite particle dissolution using fast synchrotron nano X-ray computed tomography 38 , 39 . However, none of these 4D imaging works combine the stringent four requirements needed for carrying out relevant contributions to the understanding of the mechanism(s) of Portland cement hydration at early ages: (i) water to cement mass ratio (w/c) close to 0.50, (ii) submicrometer spatial resolution, (iii) good contrast to be able to identify the different evolving components (more than eight), and (iv) relatively large scanned volume to allow hydration to progress with appropriate particle sampling, the particle sizes of commercial PCs have D v,50 ∈10-20 μm.…”

“…However, none of these 4D imaging works combine the stringent four requirements needed for carrying out relevant contributions to the understanding of the mechanism(s) of Portland cement hydration at early ages: (i) water to cement mass ratio (w/c) close to 0.50, (ii) submicrometer spatial resolution, (iii) good contrast to be able to identify the different evolving components (more than eight), and (iv) relatively large scanned volume to allow hydration to progress with appropriate particle sampling, the particle sizes of commercial PCs have D v,50 ∈10-20 μm. In particular, hard X-ray synchrotron microtomography has not the required submicrometer spatial resolution neither sufficient component contrast 35 , 40 , hard X-ray synchrotron nanotomography has not the required contrast between the components to be able to classify the hydrates 38 , 39 and soft X-ray synchrotron nanotomography has the contrast but it requires very large w/c ratios and very small fields of view which does not allow the hydrates to growth in relevant condition (i.e. confined space with low water-cement ratios) 32 .…”