2. 2
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Learning Objectives
▪ Know the meaning and the way of presentation of
chemical and mineralogical composition of cement
specific materials
▪ Know the chemical moduli applied for cement specific
materials
▪ Know the Bogue-calculation for clinker mineral phases
and the relationship with chemical moduli
3. 3
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Basic Cement Chemistry
▪ Chemical Composition
▪ Chemical Formulae
▪ Mineralogical Composition
▪ Chemical Parameters for Cement-Specific Materials
▪ Contents of Clinker Minerals According to Bogue
▪ Relationship between Chemical Moduli and Clinker
Mineral Contents
▪ Exercise for Calculation
4. 4
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Elemental Composition (weight - %)
Raw Meal
O 48.4 K 0.52
Ca 30.0 Na 0.16
C 9.5 S 0.10
Si 6.7 Ti 0.10
Al 1.9 Mn 0.07
Fe 1.4 H 0.04
Mg 1.1 P 0.03
Cl 0.01
5. 5
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Chemical Composition
L.o.I. (Loss on ignition)
SiO2
Al2O3
Fe2O3
CaO
MgO
SO3
K2O
Na2O
TiO2
Mn2O3
P2O5
Cl
F
Raw Mix
35.1
14.3
3.6
2.0
42.0
1.8
0.25
0.63
0.22
0.17
0.10
0.06
0.01
Total 100.24
▪ Elemental composition in
weight percentage.
By convention, the
elements are expressed
in form of their oxides
(exception; Cl, F).
▪ Usual sequence of
elements in cement
chemistry
▪ L.o.I.: e.g. at 1050 °C,
mainly due to CO2 and
H2O
7. 7
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Chemical Formulae
▪ The chemical formula indicates the elements occurring in a
chemical compound:
For a molecular compound, type and absolute number of
elements are given
H2O O2 C6H6
Water Oxygen Benzene
For a mineralogical compound, type and relative number of
elements are given
SiO2 CaO CaCO3 Ca3SiO5
Quartz Lime Calcite Alite
Note: In mineralogical compounds, the elements need not
necessarily occur in simple numerical ratios (impurities,
solid solution)
8. 8
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
In the cement chemistry, shorthand's are often used:
CaO SiO2 Al2O3 Fe2O3 SO3 H2O
C S A F S H
Examples:
C3S for Ca3SiO5 (Alite)
C2S for Ca2SiO4 (Belite)
C3A for Ca3Al2O6 (Aluminate)
C4AF for Ca4Al2Fe2O10 (Ferrite)
Chemical Formulae
9. 9
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Mineralogical Composition
Composition of material, expressed in weight-percentage of the
occurring minerals
Examples:
Limestone Calcite CaCO3 90%
Dolomite CaMg(CO3)2 5%
Quartz SiO2 5%
Clinker Alite C3S 58%
Belite C2S 23%
Aluminate C3A 9%
Ferrite C4AF 7%
Periclase MgO 1%
Arcanite K2SO4 1%
Free lime CaO 1%
10. 10
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Mineralogical Composition
Note: Difference between chemical and mineralogical
composition
Pure dolomite rock
Mineralogical composition: Chemical composition:
Dolomite CaMg(CO3)2: 100% L.o.l. (CO2): 47.7%
CaO: 30.4%
MgO: 21.9%
11. 11
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Chemical Parameters for Cement-Specific Materials
Titration
Content of carbonates as determined by acid-base
titration, expressed as CaCO3
% Titration = 1.786 CaO + 2.48 MgO
Applied for: Limestone
Marl
Raw Meal
12. 12
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Lime Saturation
LS =
2.80 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3
or
LSF =
CaO x 100
CaO
2.80 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3
The LS is a measure to which extent the CaO-richest compounds
C3S, C3A and C4AF can be formed without the necessary presence of
free lime. At LS > 100, free lime will unavoidably be present after
burning.
13. 13
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Lime Saturation
Applied for: Raw meal
Clinker
Cement: neat OPC only
CaO = CaOtotal – 0.7 SO3
Usual range in clinker: 85 – 100
Note: The influence of MgO can be accounted for
LS =
Max. 2% MgO may be introduced in formula (not applied in cement
specifications)
(CaO + 0.75 MgO) x 100
2.80 SiO2 + 1.18 Al2O3 + 0.65 Fe2O3
19. 19
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Content of clinker Minerals according to Bogue
▪ Percentage content of clinker minerals, assuming that
chemical equilibrium is attained, and that no impurities
are present.
C3S = 4.07 CaO – 7.6 SiO2 – 6.72 Al2O3 – 1.43 Fe2O3
C2S = 8.6 SiO2 + 5.07 Al2O3 + 2.08 Fe2O3 - 3.07 CaO
or 2.87 SiO2 – 0.754 C3S
C3A = 2.65 Al2O3 – 1.69 Fe2O3
C4AF = 3.04 Fe2O3
In reality, the mineralogical composition of industrial
clinkers differs to some extent from that calculated
according to Bogue.
20. 20
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Contents of Clinker Minerals according to Bogue
Applied for Cement - OPC only (excl. blended cements)
- Correction for CaO in CaSO4:
CaO = CaOtot – 0.70 SO3
- For AASHTO: TiO2 and P2O5 to be
added to Al2O3 (no longer for ASTM)
Clinker - CaO can be corrected for free
lime; depending on objective of
calculation
CaO = CaOtot – CaOfree
21. 21
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Significance of Clinker Minerals for Cement Properties
▪ C3S Contributes to early and late strength (1 d - …)
Increases heat of hydration
▪ C2S Contributes to late strength (28 d - …)
▪ C3A Contributes to early strength (1 – 3 d) Increases
heat of hydration
Impairs resistance to sulphate attack
▪ C4AF Little effect
22. 22
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Significance of Clinker Minerals for ASTM Cement Types
▪ Type I Portland no restrictions regarding clinker
minerals
▪ Type II Portland with moderate sulphate resistance
(and moderate heat of hydration)
C3A max. 8 %
(C3S + C3A max. 58% for moderate
heat of hydration)
▪ Type III Portland with high early strength
C3A max. 15%
(C3A max. 8% for moderate sulphate resist.
C3A max. 5% for high sulphate resist.)
23. 23
13.01.2024/Pbi/ep
Cement Course-Chemistry.ppt
Holcim Group Support Basic Cement Chemistry
Significance of Clinker Minerals for ASTM Cement Types
▪ Type IV Portland with low heat of hydration
C3S max. 35%
C2S min. 40%
C3A max. 7%
▪ Type V Portland with high sulphate resistance
C3A max. 5.0 %
C4AF + 2 C3A max. 25%
or
C4AF + 2 C2F max. 25%
