Three-Dimensional Characterization of Hardened Paste of Hydrated Tricalcium Silicate by Serial Block-Face Scanning Electron Microscopy

Abstract

With the application of a three-dimensional (3D) characterization technique, serial block-face scanning electron microscopy (SBFSEM), the 3D microstructure of a hydrated cement monomineral, tricalcium silicate (C3S), was measured with nanoscale resolution. The 3D morphologies of anhydrous particles, hydrated products, and capillary pores were visualized. Closed and open pores were discovered inside an anhydrous particle. The size and distribution of both the anhydrous C3S particles and their capillary pores were analyzed quantitatively and the porosity was determined to be 9%. The distribution of pores was found to be in a good agreement with the inner and outer product model of Hu et. al., with an inner shell distance of 860 nm. Considering the spatial resolution of the instrument and the volume of sample measured, most pores in this experiment could be characterized as capillary pores.

Investigation of the Flow Properties of CBM Based on Stochastic Fracture Network Modeling

“…(1) The linear congruence method is used to generate uniformly distributed random numbers in [0,1] interval [22], i.e., {xi+1=(axi+c)mod(m)ξi+1=xi+1m where x i+1 is a random variable corresponding to a random number ξ i+1 ; a is a multiplier; c is the increment; m is a modulus; mod(m) represents the remainder of the modulus; the subscript i is an integer; and the initial value is zero.…”

“…However, due to the complexity of the stress environment, formation history, and lithotype, the distribution patterns of FGPs in various areas and buried depths are different and cannot be characterized by in situ observations or some conventional laboratory approaches including nuclear magnetic resonance and mercury intrusion porosimetry. Micron computed tomography scanning technology and scanning electron microscopy have limitations in the description of large-scale fracture systems and the determination of fractures’ connectivity features [2,22]. Seismological surveys may be able to assess and image large-scale structures but the current technology can hardly detect widely-spreading medium and small fractures due to the resolution limit [23].…”

Terahertz Time-Domain Spectroscopic Study of Tricalcium Silicate

“…Tricalcium silicate (C 3 S) is the most critical mineral phase of Portland cement clinker, accounting for approximately 60% of the cement mass. The structure of C 3 S significantly impacts cement hydration and, therefore, the properties of cement-based materials [ 6 ]. Dolado et al [ 7 ] studied ordinary Portland cement (OPC) and geopolymer (GEO) pastes using THz spectroscopy and conducted molecular simulations to calculate the dielectric response of C–S–H and N–A–S–H gels, which are the most crucial hydration products of OPC and GEO cement pastes.…”

Reconstruction of calcium silicate hydrates using multiple 2D and 3D imaging techniques: Light microscopy, μ‐CT, SEM, FIB‐nT combined with EDX

“…This can be overcome using the FIB-nT, which is already widely adopted in material science. [2][3][4][5]9,10 It utilises a gallium ion beam to cut layer by layer of a material volume and then using the various detectors available in a SEM to image and analyse the revealed surface. This allows to reconstruct a detailed 3D-volume of the specimen.…”

“…This allows to reconstruct a detailed 3D-volume of the specimen. While some approaches to image several cubic micrometre small volumes of hydrated alite already exist, 9 none of these approaches were able to provide a detailed 3D geometry of the C-S-H-needle structure due to the sensitivity of the material to the electron and ion beam. 11,12 By combining μ-CT with FIB-nT, not only the scale range is significantly extended but also more information becomes available.…”