Three-dimensional imaging of cement microstructure evolution during hydration

Abstract

Synchrotron radiation is used for X-ray computed tomography to characterise the hydration process of Portland cement. Quantitative determination of the three-dimensional absorption coefficient distribution due to the use of monochromatic radiation and the achieved high spatial resolution allows the study of the spatial microstructure of cement volume during hydration. The present study has demonstrated the potential of the method for real-time imaging of the evolution of cement structure after solidification. The method yields three-dimensional (3-D) images of the sample volume in a non-destructive manner. Thus, by reiterated imaging of the same sample region at different times, processes in the sample volume can be tracked. During cement hydration, effects such as the formation and further evolution of microcracks and pores - mainly related to autogeneous shrinkage - could be observed for the first time in the cement volume with up to 1 mu m resolution. Image analysis of the acquired 3-D data sets allows the determination of the temporal evolution of microporosity and of the fraction of contiguous pore volume for different water: cement ratios of the initial cement paste

Quantification of tortuosity in hardened cement pastes using synchrotron-based X-ray computed microtomography

“…Synchrotron-based microtomography have been used to porous building materials [4], as well as, to other cementitious materials [5][6][7][8][9] by various researchers in the US and Europe. At SPring-8, a third-generation synchrotron radiation facility in Japan, the pore structure of hardened cement pastes and mortar was also examined at a sub-micron resolution [10][11].…”

Application of X-Ray CT to Study Diffusivity in Cracked Concrete Through the Observation of Tracer Transport

“…There is, however, a trade-off, such that the maximum sample size for the higher-resolution systems is limited to less than a few millimeters, whereas specimens on the scale of a few centimeters may be used with lower resolution systems. For cement-based materials, X-ray CT has been applied to a variety of research areas including pore structure characterization and freeze-thaw damage (Bentz et al 2000;Burlion et al 2006;Gallucci et al 2007;Helfen et al 2005;Lu et al 2006;Hitomi et al 2004;Promentilla et al 2008Promentilla et al , 2009Promentilla et al , 2010Sugiyama et al 2010).…”

Microstructural Evolution within the Interphase between Hardening Overlay and Existing Concrete Substrates

“…Understanding the microstructural evolution in concrete and cement paste during hardening is a very challenging issue. Recently, He et al [46], Helfen et al [47], and Sun et al [48] used high resolution X-ray micro-computed tomography (micro-CT) for this purpose. This advanced technique has been proven to provide information on the real size and spatial distribution of the pores, which cannot be obtained by classical techniques [49][50][51][52][53][54].…”