Hillebrandite

Formula : Ca2SiO3(OH)2:0.17H2O

Space group: 
Orthorhombic - Pyramidal H-M Symbol (mm2) Space Group: C mc21
Dana class: 
65.2.3.1 (65) Inosilicate Single-Width Unbranched Chains, W= (65.2) with chains P=3 (65.2.3) Dana Group
High temperature: 
Hydrothermally synthetized at 300C, hillebrandite is a natural analog of the calcium silicate hydrate (CSH) phase that forms a major part of Portland cement. Stability of Hillebrandite at low temperature cannot be dismissed.
Geological context: 
Contact zone between limestone and diorite.

Dernière mise à jour le 25.01.2021

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
 V°
cm3·mol-1
 ΔGºf
J·mol-1
 ΔHºf
J·mol-1
 Sº
J·mol-1·k-1
 CP
J·mol-1·K-1
193.317 72.580 (Ref.: 95dai/pos) Dai, Y., and Post, J. E,. 1995, Crystal structure of hillebrandite: a natural analogue of calcium silicate hydrate (CSH) phases in Portland cement: American Mineralogist, v. 80, p. 841-844. -2481411 (Ref.: 10abla/bou) Blanc, Ph.; Bourbon, X.; Lassin, A.; Gaucher, E.C. 2010 - Chemical model for cement-based materials: Temperature dependence of thermodynamic functions for nanocrystalline and crystalline C-S-H phases. Cement and Concrete Research, 40, p. 851-867 -2662480 (Ref.: 56new) Newman, E., 1956., Heats. of Formation of Xonotlite, Hillebrandite, and Foshagite: Journal of Research of the National Bureau of. Standards, v. 57, p. 27-30. 177.896 (Ref.: Internal calculation) 177.46 (Ref.: 10abla/bou) Blanc, Ph.; Bourbon, X.; Lassin, A.; Gaucher, E.C. 2010 - Chemical model for cement-based materials: Temperature dependence of thermodynamic functions for nanocrystalline and crystalline C-S-H phases. Cement and Concrete Research, 40, p. 851-867
CP(T) = a + b·T + ·c·T-2 (T in Kelvin)
a
J·mol-1·K-1
 b * 103
J·mol-1·K-2
 c * 10-5
J·K·mol-1
 Maier Kelley Ref.
177.46 0.00 0.00 (Ref.: 10abla/bou) Blanc, Ph.; Bourbon, X.; Lassin, A.; Gaucher, E.C. 2010 - Chemical model for cement-based materials: Temperature dependence of thermodynamic functions for nanocrystalline and crystalline C-S-H phases. Cement and Concrete Research, 40, p. 851-867
Reaction properties

Hillebrandite + 4H+ ⇌ 2Ca+2 + H4SiO4 + 1.17H2O

298.15 K, 1 bar log10K: 36.95 ΔH°r:-216802 J·mol-1 (Ref.: 56new) Newman, E., 1956., Heats. of Formation of Xonotlite, Hillebrandite, and Foshagite: Journal of Research of the National Bureau of. Standards, v. 57, p. 27-30.
T(°C) 0 25 60 100 150 200 250 300
log10K 40.40 36.95 32.95 29.30 25.72 22.89 20.54 18.46
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-907.356485 -0.127193 63081.088801 325.619642 -3117433.029498