Afwillite

Formula : Ca3Si2O4(OH)6

Space group: 
Monoclinic - Sphenoidal H-M Symbol (2) Space Group: P 21
Dana class: 
52.4.7.1 (52 )Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O (52.4) with cations in [6] and/or > [6] coordination (52.4.7) Afwillite and related species
High temperature: 
Probably related with the weathering. Also as artificial mineral found in the concrete
Geological context: 
A product of contact metamorphism of limestones.

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
342.447 129.530 (Ref.: 52meg) Megaw D., 1952, The structure of afwillite, Ca3(SiO3OH)2*2H2O, Locality: Scawt Hill, Northern Ireland, Act. Cryst.D60, v. 5, p. 477-495. -4469122 (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 -4853820 (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. 851-867 289.905 (Ref.: Internal calculation) 303.55 (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.
303.55 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

Afwillite + 6H+ ⇌ 3Ca+2 + 2H4SiO4 + 2H2O

298.15 K, 1 bar log10K: 49.42 ΔH°r:-264562 J·mol-1 (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
T(°C) 0 25 60 100 150 200 250 300
log10K 53.62 49.42 44.55 40.14 35.88 32.56 29.82 27.40
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1614.282156 -0.218340 107388.130079 578.887812 -5671338.992245