Pair distribution function analysis of nanostructural deformation of calcium silicate hydrate under compressive stress

Abstract

Despite enormous interest in calcium silicate hydrate (C-S-H), its detailed atomic structure and intrinsic deformation under an external load are lacking. This study demonstrates the nanostructural deformation process of C-S-H in tricalcium silicate (C 3 S) paste as a function of applied stress by interpreting atomic pair distribution function (PDF) based on in situ X-ray scattering. Three different strains in C 3 S paste under compression were compared using a strain gauge, Bragg peak shift, and the real space PDF. PDF refinement revealed that the C-S-H phase mostly contributed to PDF from 0 to 20 A whereas crystalline phases dominated that beyond 20 A. The short-range atomic strains exhibited two regions for C-S-H: I) plastic deformation (0-10 MPa) and II) linear elastic deformation (>10 MPa), whereas the long-range deformation beyond 20 A was similar to that of Ca(OH) 2 . Below 10 MPa, the short-range strain was caused by the densification of C-S-H induced by the removal of interlayer or gel-pore water. The strain is likely to be recovered when the removed water returns to C-S-H. K E Y W O R D Scalcium silicate hydrate, deformation, portland cement, X-ray methods

Multiscale understanding of tricalcium silicate hydration reactions

“…7 . Hillebrandite has now been included as it has been very recently reported as a good model for the nanocrystalline component of C-S-H gel 50 but it gave a poor fit to our PDF data. Supplementary Table 1 gives the R W values for each PDF fit and the quantitative phase analysis results.…”

Determination of atomistic deformation of tricalcium silicate paste with high‐volume fly ash

“…The loading rate was maintained as 0.01 mm/ min, which was same as our previous study. 51 The loading axis was mostly parallel to the X-ray scattering vector. The uniaxial macroscopic strain of the sample was obtained using two-bonded foil strain gauges.…”

“…55,56 Nevertheless, Vempati et al 57 reported that the difference of interatomic elastic strain of metallic glass under uniaxial loading between the full isotropic analysis via the Fourier transformation and the full anisotropic analysis via the Bessel transformation was not significant. Therefore, the elastic strain was determined using isotropic assumption and identical analytical procedure with our previous PDF study of pure C 3 S paste 51 to elucidate the change of elastic strain due to FA incorporation into the pure C 3 S system.…”

Inorganic Polymers From CaO-FeOx-SiO2 Slag: The Start of Oxidation of Fe and the Formation of a Mixed Valence Binder

“…As this practically decelerates the reaction kinetics toward negligible speeds, it enables their ex-situ study (Krebs et al, 2005;Kamnev et al, 2014). In-situ kinetic studies have also been performed using synchrotron radiation techniques, e.g., X-ray/neutron total scattering on the alkali-activation of metakaolin (Bell et al, 2008;White et al, 2011White et al, , 2013a, blast furnace slag (White et al, 2013b;Garg and White, 2017) and on conventional cements (Grangeon et al, 2017;Bae et al, 2018;Cuesta et al, 2019). With these techniques, the short and intermediate range ordering can be investigated in great detail.…”