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

Jee, H.*; Im, S.*; Kanematsu, Manabu*; Suzuki, Hiroshi; Morooka, Satoshi; Koyama, Taku*; Machida, Akihiko*; Bae, S.*

Journal of the American Ceramic Society, 103(12), p.7188 - 7201, 2020/12

https://doi.org/10.1111/jace.17404

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

Bae, S.*; Jee, H.*; Kanematsu, Manabu*; Shiro, Ayumi*; Machida, Akihiko*; Watanuki, Tetsu*; Shobu, Takahisa; Suzuki, Hiroshi

Journal of the American Ceramic Society, 101(1), p.408 - 418, 2018/01

https://doi.org/10.1111/jace.15185

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 (CS) 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 CS paste under compression were compared using a strain gauge and the real and reciprocal space PDFs. PDF refinement revealed that the C-S-H phase mostly contributed to PDF from 0 to 20 whereas crystalline phases dominated that beyond 20. 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 was similar to that of Ca(OH). 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.

Models of Cement-Water Interaction and a Compilation of a Associated Thermodynamic Data

Savage, D.*; Lemke, K.*; Sasamoto, Hiroshi; Shibata, Masahiro; Arthur, R. C,*; Yui, Mikazu

JNC TN8400 2000-004, 30 Pages, 2000/01

JNC-TN8400-2000-004.pdf:1.26MB

Modeling approaches that have been proposed for cement-water system are reviewed in this report, and relevant supporting thsrmodynamic data are compiled. The thermodynamic data include standard molal thermodynamic properties of minerals and related compounds comprising cements, and equilibrium constants for associated hydrolysis reactions. Similar data for minerals that are stable in hyperalkaline geologic environments (e.g., zeolites) are also included because these minerals could be formed as hyperalkaline fluids emanating from cementitious matelials in a repository for radioactive wastes interact with the surrounding host rock. Standard molal properties (i.e., standard molal Gibbs free energies and enthalpies of formation and standard molal entropies), and/or equilibrium constants for associated hydrolysis reactions, are included for. (1)cement minerals and related compounds (Reardon, 1992; Glasser et al., 1999) (2)calcium-silicate hydrate minerals (Sarkar et al., 1982), and (3)zeolites (calorimetric and estimated values from various sources) All these data are accepted at face value, and it is therefore cautioned that the data, considered as a whole, may not be internally consistent. It is also important to note that the accuracy of these data have not been evaluated in the present study. Several models appropriate for cement-water systems have been proposed in recent years. Most are similar in the sense that they represent empirical fits to laboratory data for the CSH gel-water system, and therefore not thermodynamically defensible. An alternative modeling approach based on thermodynamic principles of solid-solution behavior appropriate for CSH gel has recently been proposed, however. It is reviewed in the present study, and evaluated in relation to experimental results obtained by JNC on cement-water interactions. The solid-solution model is based upon a thermodynamically- and structually-justifiable description of CSH gel in terms of a non-ideal ...