cement hydration

[sama.k]

Hello,
I am new to Phreeqc modelling, I would like to model the cement hydration. Water solution and cement are defined by the solution and solid solution keywords, respectively. Some dissolution reactions are defined by phases keyword. Finally, use keyword is applied for reaction between water and cement but I'm not sure this keyword is appropriate for hydration. 
Any help or advice will be greatly appreciated.
Here is the input data for my model.
SOLID_SOLUTIONS 1
    Minor
        -comp Na2O 0.0053
        -comp K2O 0.0006
        -comp MgO 0.0446
    cement
        -comp C2S 0.0598
        -comp C3S 0.2912
        -comp C3A 0.0277
        -comp C4AF 0.0174
    other
        -comp Gypsum 0.018
        -comp Calcite 0.0059
        -comp Na2SO4 0.0014
        -comp K2SO4 0.0076
        -comp CaO_Free 0.0165
PHASES
Anhydrite
    CaSO4 = Ca+2 + SO4-2
    log_k     -4.36
    delta_h   -1.71 kJ
Brucite
    Mg(OH)2 + 2H+ = 2H2O + Mg+2
    log_k     17.07
    delta_h   -115.66 kJ
C3AH6
    Ca3Al2(OH)12 + 12H+ = 2Al+3 + 3Ca+2 + 12H2O
    log_k     82.22
    delta_h   -595.76 kJ
C3FH6
    Ca3Fe2(OH)12 + 12H+ = 3Ca+2 + 2Fe+3 + 12H2O
    log_k     73.65
    delta_h   -516.96 kJ
Calcite
    CaCO3 = CO3-2 + Ca+2
    log_k     -8.48
    delta_h   -2.297 kJ
CASH_5CA
    (CaO)1.25(Al2O3)0.125(SiO2):1.625H2O + 3.25H+ = 0.25Al+3 + 1.25Ca+2 + 1.25H2O + H4SiO4
    log_k     22
    delta_h   -141.58 kJ
CASH_INFCA
    (CaO)(Al2O3)0.15625(SiO2)1.1875:1.65625H2O + 2.9375H+ = 0.3125Al+3 + Ca+2 + 0.75H2O + 1.1875H4SiO4
    log_k     16.6
    delta_h   -110.67 kJ
CSH_T2C
    (CaO)1.5(SiO2):2.5H2O + 3H+ = 1.5Ca+2 + 2H2O + H4SiO4
    log_k     25.88
    delta_h   -127.1 kJ
CSH_T5C
    (CaO)1.25(SiO2)1.25:2.5H2O + 2.5H+ = 1.25Ca+2 + 1.25H2O + 1.25H4SiO4
    log_k     18.74
    delta_h   -83.46 kJ
CSH_Jen
    (CaO)1.667(SiO2):2.1H2O + 3.334H+ = 1.667Ca+2 + 1.767H2O + H4SiO4
    log_k     29.6
    delta_h   -148.44 kJ
CSH_TobH
    (CaO)(SiO2)1.5:2.5H2O + 2H+ = Ca+2 + 0.5H2O + 1.5H4SiO4
    log_k     13.18
    delta_h   -47.83 kJ
Ettringite
    Ca6Al2(SO4)3(OH)12:26H2O + 12H+ = 2Al+3 + 6Ca+2 + 38H2O + 3SO4-2
    log_k     57.73
    delta_h   -389.36 kJ
Gypsum
    CaSO4:2H2O = Ca+2 + 2H2O + SO4-2
    log_k     -4.58
    delta_h   -0.109 kJ
Hemicarboaluminate
    Ca4Al2(CO3)0.5(OH)13:5.5H2O + 13H+ = 2Al+3 + 0.5CO3-2 + 4Ca+2 + 18.5H2O
    log_k     87.88
    delta_h   -604.27 kJ
Hydrotalcite
    Mg4Al2(OH)14:3H2O + 14H+ = 2Al+3 + 17H2O + 4Mg+2
    log_k     75.97
    delta_h   -607.91 kJ
Monocarboaluminate
    Ca4Al2(CO3)(OH)12:5H2O + 12H+ = 2Al+3 + CO3-2 + 4Ca+2 + 17H2O
    log_k     71.54
    delta_h   -533.14 kJ
Monosulfoaluminate
    Ca4Al2(SO4)(OH)12:6H2O + 12H+ = 2Al+3 + 4Ca+2 + 18H2O + SO4-2
    log_k     73.68
    delta_h   -553.08 kJ
Portlandite
    Ca(OH)2 + 2H+ = Ca+2 + 2H2O
    log_k     22.79
    delta_h   -129.66 kJ
Stratlingite
    Ca2Al2SiO2(OH)10:3H2O + 10H+ = 2Al+3 + 2Ca+2 + 11H2O + H4SiO4
    log_k     51.42
    delta_h   -408.12 kJ
Silicic_acid
    H4SiO4 = 2H2O + SiO2
    log_k     -3.96
    delta_h   323.37 kJ
EQUILIBRIUM_PHASES 1
    Anhydrite 0 0
    Brucite   0 0
    C3AH6     0 0
    C3FH6     0 0
    CASH_5CA  0 0
    CASH_INFCA 0 0
    CSH_Jen   0 0
    CSH_T2C   0 0
    CSH_T5C   0 0
    CSH_TobH  0 0
    Calcite   0 0
    Ettringite 0 0
    Gypsum    0 0
    Hemicarboaluminate 0 0
    Hydrotalcite 0 0
    Monocarboaluminate 0 0
    Monosulfoaluminate 0 0
    Portlandite 0 0
    Stratlingite 0 0
SOLUTION 1
    temp      20
    pH        7
    pe        4
    redox     pe
    units     mmol/kgw
    density   1
    -water    40 # kg

USE solid_solutions 1
USE solution 1

[dlparkhurst]

Let's start with the SOLID_SOLUTION definition. Multiple solid solutions may be defined, as you have with minor, cement, other; however, the components of each solid solution must be mineral names that have been defined in PHASES. The idea is not to define the elemental composition of the solid solutions to allow one or more solid solutions (mixtures of end-member minerals) to equilibrate with the solution.

Perhaps you want to add the solid composition as a REACTION, in which case you could define the elemental composition using charge balanced elements, like CaO, Na2O, CaSO4, etc. You should not use strictly Ca, Na, etc, because these are equivalent to adding pure metals, which will result in extreme redox reactions.

Then you would either include EQUILIBRIUM_PHASES as you have, or construct plausible SOLID_SOLUTION definitions. PHREEQC has been used for cement solid solutions many times in the literature, and even in this forum. You should probably do a little searching to see how other people have addressed the simulations.