Ettringite

Formula : Ca6Al2(SO4)3(OH)12:26H2O

Family: 
Sulfates
Space group: 
Hexagonal - Dihexagonal Dipyramidal H-M Symbol (6/m 2/m 2/m) Space Group: P 63/mmc
Dana class: 
31.10.2.1 (31) Hydrated Sulfates Containing Hydroxyl or Halogen (31.10) miscellaneous (31.10.2)Dana Group
High temperature: 
The upper stability of this mineral is limited around 60C to 90C.
Geological context: 
Related to the leaching of contact metamorphism halos in marl or natural cements present in the rock at Maqarin in Jordan. Layers of bituminous marlstone burned at one point in time. Bitumen is a natural form of asphalt, and marlstone is a kind of clay-bearing limestone. Also found in concrete.

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
1255.110 710.320 (Ref.: 70moo/tay) Moore A.E., Taylor H.F.W., 1970. Acta Cryst., B26, 386-393 -15210275 (Ref.: 10bbla/bou) Blanc, Ph.; Bourbon, X.; Lassin, A.; Gaucher, E.C. 2010 - Chemical model for cement-based materials: Thermodynamic data assessment for phases other than C-S-H. Cement and Concrete Research, 40, p. 1360-1374. -17544526 (Ref.: 63ber/new) Berman H.A. and Newman E.S. 1963 - Heat of formation of calcium aluminate monosulfate at 25 C, Journal of Research of the National Bureau of Standards. A, Physics and Chemistry, 65, pp. 1-13 1883.750 (Ref.: Internal calculation) 2174.36 (Ref.: 79ede/sat) Ederova, J., and Satava, V., 1979, Heat capacities of C3AH6, C4ASH12 and C6AS3H32: Thermochimica Acta, v. 31, p. 126-128
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.
1939.12 789.00 0.00 (Ref.: 79ede/sat) Ederova, J., and Satava, V., 1979, Heat capacities of C3AH6, C4ASH12 and C6AS3H32: Thermochimica Acta, v. 31, p. 126-128
Reaction properties

Ettringite + 12H+ ⇌ 2Al+3 + 6Ca+2 + 3SO4-2 + 38H2O

298.15 K, 1 bar log10K: 57.01 ΔH°r:-379834 J·mol-1 (Ref.: 63ber/new) Berman H.A. and Newman E.S. 1963 - Heat of formation of calcium aluminate monosulfate at 25 C, Journal of Research of the National Bureau of Standards. A, Physics and Chemistry, 65, pp. 1-13
T(°C) 0 25 60 100 150 200 250 300
log10K 62.97 57.01 49.89 43.16 36.08 29.78 23.57 16.64
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-6674.571203 -1.047429 378706.292033 2426.618570 -20518894.725685