Cement – Specification
and Performance
Hugh Wang
Eduardo Caballero
CEMEX USA
hugh.wang@cemex.com
Use of cement:
• Cement is ONLY one of the ingredients in any
applications – well cementing or construction
concreting.
• The specified quality parameters of cement are tested
without considering other ingredients.
• Lessons learned from concrete mixtures - interaction
of cement with other ingredients can be critical to
performance.
Production of quality well cement involves:
Grinding
Proportioning
Chemistry
Ca, Si, Al, Fe
Mineral
C3S, C2S,
C3A, C4AF
Physical
fineness,
strength, TT, FF
etc
Burning
Desired clinker characteristics for well cement:
Mineral
C3S, C2S,
C3A, C4AF
• Well crystallized alite;
• Optimize burning condition in order to minimize f-CaO
content;
• Generally very low in C3A content – a challenge for
kiln operation.
Physical properties requirements:
Physical
fineness,
strength, TT,
free fluid,
etc
• Fineness;
• Thickening time (TT);
• Free fluid (FF).
Potential conflicting response:
• Fineness vs TT;
• Fineness vs FF.
Specifications - ASTM vs API :
API
Ordinary
A
C
ASTM
MSR
B
C
D, E, F
HSR
G
H
B
C
SO3, max% 3.5 4.5 3.0 3.5 3.0 3.0 3.0 3.0 3.5
C3S%
48/58
min/max
C3A, max%
8
15
C4AF+2C3A
max%
Blaine, min
280 400 280 400
m2/kg
w/c %
46 56 46 56 38
D, E, F
3.0
III: high early strength V:
II:
H Ordinary MSR Ordinary MSR HSR HSR
I:
G
3.0 3.0 3.0/3.5D
D
D
3
4.5
8
15
3.5
D
3.5
D
3
8
5
260
38
5
25
280 400
56
D
48/65
24
44 38 46
2.3
260
44 38
260
48.5
• Fineness: ASTM lowered the limit from 280 to 260 m2/kg;
• SO3: ASTM adopted performance based specification;
D It
is permissible to exceed the values in the table for SO3 content, provided it
has been demonstrated by Test Method C1038 that the cement with the
increased SO3 will not develop expansion exceeding 0.020 % at 14 days.
• C3S: No requirement for MSR and HSR cements.
• C4AF+2C3A: 24 API vs 25 ASTM.
Mineral calculation – ASTM:
Mineral calculation – ASTM:
Mineral calculation – API 10A:
Mineral calculation – API vs ASTM:
When Al2O3/Fe2O3 is
C3S =
C2S =
API
ASTM
> 0.64
≥ 0.64
4.071CaO - 7.600SiO2 - 6.718Al2O3 -1.430Fe2O3 - 2.852SO3
C3A =
2.650Al2O3 - 1.692Fe2O3
3.043Fe2O3
C4AF =
When Al2O3/Fe2O3 is
C3S =
C2S =
≤ 0.64
< 0.64
4.071CaO - 7.600SiO2 -4.479Al2O3 -2.859Fe2O3 - 2.852SO3
2.867SiO2 - 0.7544C3S
No requirment
C3A =
C4AF =
2.867SiO2 - 0.7544C3S
No requirment
0
3.04Fe2O3
2.100Al2O3 - 1.702Fe2O3
Discussions – ASTM vs API
• Minimum blaine 400 m2/kg for API Class-C: if high blaine is intended
for early strength, its benefit may be potentially reduced due to the
higher water demand.
• Minimum blaine for other types of cements should be harmonized with
ASTM requirements from 280 to 260 m2/kg;. This will improve
thickening time performance.
• Why ASTM revised cement SO3 content?
– Critical in the mixtures containing supplementary cementitious
materials (SCM) and chemical admixtures. Construction industry
has gone through the learning process.
– Potential incompatibility problems in the mixtures shall be
considered when complex components are used in slurry.
Energy release rate mW/g
Cement hydration rate profile
I II
III
IV
V
Maximum heat
release rate
On-set of
acceleration
stage
Conversion of
ettringite to
mono-sulfate
Time in hours
Stage I: dissolution
Stage III: acceleration
Stage V: steady
Stage II: induction (dormant)
Stage IV: deceleration
Cement hydration heat release – strength indication
Incompatibility: uncontrolled early hydration
Power (mW/g)
4
3
2
1
0
0
Cmt
4
8
12
Time (h)
Cmt+24%C-FA
16
20
24
Cmt+24%C-FA+WR&Retarder
0
Energy (J/g)
44 88 132 176 220
Incompatibility: slow strength development
0
Cmt
4
8
Cmt+24%C-FA
12
16
Time (h)
20
24
Cmt+24%C-FA+WR&Retarder
Well cement examples:
SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O
TA00 20.53 4.08 6.63 65.45 0.81 0.94 0.12
TA01 20.30 4.04
6.59 65.39 0.80 1.41 0.14
TA03 19.95 3.95
6.51 65.00 0.78 2.35 0.13
TA05 19.62 3.84
6.42 64.68 0.77 3.31 0.13
C3S
TA00
TA01
TA03
TA05
70.51
70.94
70.00
69.23
K2O f-CaO
0.41
0.40
0.40
0.39
0.35
C2S C4AF+C2F
4.32
3.34
3.08
2.72
19.85
19.69
19.36
18.99
Hydration rate at 23˚C (73˚F)
5
Power (mW/g)
TA03
TA05
3
2
0
1
7
TA00
13
Time (h)
TA01
TA03
19
TA05
25
380
Hydration heat at 23˚C (73˚F)
60
Energy (J/g)
140
220
300
TA05
1
10
TA00
19
28
37
46
Time (h)
55
TA01
TA03
TA05
64
73
Hydration rate at 38˚C (100˚F)
TA03
Power (mW/g)
9
6
TA05
3
0
1
7
TA00
13
Time (h)
TA01
TA03
19
TA05
25
390
Hydration heat at 38˚C (100˚F)
40
Energy (J/g)
110 180 250 320
TA05
1
10
TA00
19
28
37
46
Time (h)
55
TA01
TA03
TA05
64
73
Example: cement and fly ash combination
6
100
5
80
4
60
3
40
2
20
1
0
0
0
Class-C
35
Consistency (Bc)
70
105
Pressure (kpsi)
Consistency (Bc)Temp (°F)
120
140
Time (min)
Temperature(F)
Pressure(kpsi)
Well cement with 50% Class-C fly ash (C-FA)
6
100
5
80
4
60
3
40
2
20
1
0
0
44
Consistency (Bc)
88
132
176
• Viscosity increase
220
Time (min)
Temperature(F)
Pressure(kpsi)
26
5
22
4
18
3
14
2
10
1
6
0
0
20
Class-C+50% FA
40
60
80
100
120
140
Time (min)
Consistency (Bc)
Pressure(kpsi)
160
Pressure (kpsi)
Consistency (Bc)
0
Class-C+50% FA
Pressure (kpsi)
Consistency (Bc)Temp (°F)
120
120
6
100
5
80
4
60
3
40
2
20
1
0
0
46
138
184
230
26
5
22
4
18
3
14
2
10
1
6
0
Time (min)
Temperature(F)
Pressure(kpsi)
0
20
Class-C+50% FA
40
60
80
100
120
140
Time (min)
Consistency (Bc)
Pressure(kpsi)
160
Pressure (kpsi)
Consistency (Bc)
92
Consistency (Bc)
0
Class-C+50% FA
+1.5% Gypsum
Pressure (kpsi)
Consistency (Bc)Temp (°F)
Well cement with 50% C-FA and 1.5% gypsum
Viscosity profile comparison
80
60
• Gypsum addition eliminates
high viscosity during early
stages
40
20
0
0
Class-C
46
230
26
Class-C+50%FA+1.5% gyp
22
138
92
Time (min)
Class-C+50%FA
184
Consistency (Bc)
Consistency (Bc)
100
18
14
10
6
0
20
40
60
80
100
120
140
160
Time (min)
Class-C
Class-C+50%FA
Class-C+50%FA+1.5% gyp
SO3: Supply - Demand Rule
SO3
supply
SO3
demand
If SO3 supply is greater than demand
If SO3 supply is greater than demand
If SO3 supply is less than demand
If SO3 supply is less than demand
Recommendations
• In order to make well cement more robust for slurry mixtures
containing SCM and chemical admixtures, the cement SO3 needs to
be optimized.
• The 280 m2/kg blaine requirement needs to be revised to 260 m2/kg,
this will help to improve thickening time.
• The minimum blaine 400 m2/kg for Class-C cement may be eliminated
by specifying the strength requirement.
• Harmonize cement mineral phase calculation to reflect lasted advance
in understanding cement chemistry.