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Table 3 Reactions considered in the HYDROGEOCHEM 5.0 model

From: Influences of specific ions in groundwater on concrete degradation in subsurface engineered barrier system

Aqueous complexation reactions (25 °C)
No. Reaction log K No. Reaction log K
1 H2O = OH + H+ −14 20 K+ + Cl = KCl −1.49
2 Al3+ + 4OH = AlO2  + 2H2O 33.12 21 K+ + OH = KOH −0.46
3 Al(OH)2+ = Al3+ + 2(OH) −3.41 22 K+ + SO4 2− = KSO4 0.85
4 Al(OH)2+ = Al3+ + (OH) −9.05 23 NaAlO2 + 2H2O = Al3+ + Na+ + 4OH −18.37
5 Al(SO4) 2  = Al3+ + 2SO4 2− −4.9 24 Na+ + Cl = NaCl −0.78
6 AlSO2 + = Al3+ + SO4 2− −3.01 25 NaHCO3 = HCO3  + Na+ −0.15
7 Ca+2 + HCO3  + OH = CaCO3 + H2O 6.895 26 Na+ + H4SiO4 + OH = NaH3SiO4(aq) + H2O 5.99
8 Ca2+ + Cl = CaCl+ −0.7 27 Na+ + HCO3  + OH = NaCO3  + H2O 4.19
9 CaCl2 = Ca2+ + 2Cl 0.64 28 Na+ + OH = NaOH −0.79
10 CaHCO3 + = Ca2+ + HCO3 −1.05 29 Na+ + SO4 2− = NaSO4 0.82
11 Ca2+ + OH = CaOH+ −1.15 30 HCO3  + 9 H+ + 8 e = CH4(aq) + 3 H2O 30.742
12 Ca2+ + SO4 2− = CaSO4 2.11 31 2 H2O = O2(aq) + 4 H+ + 4 e −86.08
13 HCO3  = CO2(aq) + OH 7.66 32 2 H+ + 2 e = H2(aq) −3.15
14 HCO3  + OH = CO3 2− + H2O −3.67 33 SO4 2− + 8 H+ + 8 e = S2− + 4 H2O 20.732
15 HAlO2(aq) + H2O = Al3+ + 3(OH) −25.57 34 SO4 2− + 9 H+ + 8 e = HS + 4 H2O 33.65
16 HCl +OH = Cl + H2O 13.33 35 SO4 2− + 10 H+ + 8 e = H2S + 4 H2O 40.644
17 H4SiO4 + 2OH = H2SiO4 2− + 2H2O 5 36 Fe+3 + e = Fe+2 13.02
18 H2SO4 + 2(OH) = SO4 2− + 2H2O 29.02 37 Fe+3 + 4 H2O = Fe(OH) 4  + 4 H+ −21.6
19 HSO4  + OH = H2O + SO4 2− 12.02    
Precipitation-dissolution reactions (25 °C)
No. Mineral Reaction log K Molar volume (dm3/mol)
1 Calcite HCO3  + Ca2+ + OH = CaCO3 + H2O 12.151 0.03693
2 Portlandite Ca2+ + 2OH = Ca(OH)2 5.20 0.03300
3 Ettringite 2Al3+ + 6Ca2+ + 26H2O + 3SO4 2− + 12OH = Ca6Al2(SO4)3(OH)12·26H2O 111.03 0.71032
4 Quartz H4SiO4 = SiO2 + 2H2O 3.98 0.02269
5 Gypsum Ca2+ + SO4 2− + 2H2O = CaSO4·2H2O 4.58 0.07470
6 Hydrogarnet 2Al3+ + 3Ca2+ + 12OH = Ca3Al2(OH)12 87.68 0.14952
7 Friedel’s salt 2Al3+ + 4Ca2+ + 2Cl + 4H2O + 12OH = 2Ca2Al(OH)6Cl·2H2O 93.07 0.27624
8 Thaumasite 3Ca2++H4SiO4 + SO4 2−+HCO3 +11H2O +3OH = CaSiO3·CaSO4·CaCO3·15H2O 31.70 0.32940
9 Monocarboaluminate 2Al2+ +HCO3  + 4Ca2+ + 3.68H2O + 13OH = 3CaO·Al2O3·CaCO3·10.68H2O 101.45 0.26196
10 Pyrite FeS2 + 2 H+ + 2 e = Fe+2 + 2 HS −18.479 0.02394