Cement – Specification and Performance

Hugh WangEduardo Caballero

CEMEX USAhugh.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.

MineralC3S, C2S, C3A, C4AF

Burning

ChemistryCa, Si, Al, Fe

Proportioning

Physicalfineness,

strength, TT, FFetc

Grinding

Production of quality well cement involves:

Desired clinker characteristics for well cement:

MineralC3S, 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:

Physicalfineness,

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 :

• 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.

A C B C D, E, F G H B C D, E, F G H Ordinary MSR HSR

3.5 4.5 3.0 3.5 3.0 3.0 3.0 3.0 3.5 3.0 3.0 3.0 3.0/3.5D 3D 4.5D 3.5D 3.5D 2.3D

15 8 15 8 5 5

25

280 400 280 400 280 400 260 260 260

46 56 46 56 38 44 38 46 56 38 44 38

48/65

48.5

24

3

Ordinary MSR HSR

w/c %

Blaine, min

m2/kg

48/58

8

C3S% min/max

C3A, max%

V: HSR

C4AF+2C3A max%

SO3, max%

API ASTM

I: Ordinary

II: MSR

III: high early strength

Mineral calculation – ASTM:

Mineral calculation – ASTM:

Mineral calculation – API 10A:

Mineral calculation – API vs ASTM:

API ASTM When Al2O3/Fe2O3 is > 0.64 ≥ 0.64

C3S =

C2S = No requirment 2.867SiO2 - 0.7544C3S

C3A =

C4AF =

When Al2O3/Fe2O3 is ≤ 0.64 < 0.64

C3S =

C2S = No requirment 2.867SiO2 - 0.7544C3S

C3A =

C4AF = 3.04Fe2O3 2.100Al2O3 - 1.702Fe2O3

3.043Fe2O3

2.650Al2O3 - 1.692Fe2O3

4.071CaO - 7.600SiO2 - 6.718Al2O3 -1.430Fe2O3 - 2.852SO3

0

4.071CaO - 7.600SiO2 -4.479Al2O3 -2.859Fe2O3 - 2.852SO3

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.

Cement hydration rate profile

I II III IV V

Stage I: dissolution Stage II: induction (dormant)Stage III: acceleration Stage IV: decelerationStage V: steady

Time in hours

En

erg

y re

leas

e r

ate

mW

/g

Maximum heat release rate

On-set of acceleration stage

Conversion of ettringite to mono-sulfate

Cement hydration heat release – strength indication

0

1

2

3

4

0 4 8 12 16 20 24Time (h)

Pow

er (

mW

/g)

Cmt Cmt+24%C-FA Cmt+24%C-FA+WR&Retarder

Incompatibility: uncontrolled early hydration

04

48

81

32

17

62

20

0 4 8 12 16 20 24Time (h)

En

erg

y (J

/g)

Cmt Cmt+24%C-FA Cmt+24%C-FA+WR&Retarder

Incompatibility: slow strength development

Well cement examples:

SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O K2O f-CaO

TA00 20.53 4.08 6.63 65.45 0.81 0.94 0.12 0.41TA01 20.30 4.04 6.59 65.39 0.80 1.41 0.14 0.40

TA03 19.95 3.95 6.51 65.00 0.78 2.35 0.13 0.40

TA05 19.62 3.84 6.42 64.68 0.77 3.31 0.13 0.39

0.35

C3S C2S C4AF+C2F

TA00 70.51 4.32 19.85TA01 70.94 3.34 19.69TA03 70.00 3.08 19.36TA05 69.23 2.72 18.99

Hydration rate at 23˚C (73˚F)

0

2

3

5

1 7 13 19 25Time (h)

Pow

er (

mW

/g)

TA00 TA01 TA03 TA05

TA03

TA05

6014

022

030

038

0

1 10 19 28 37 46 55 64 73Time (h)

Ene

rgy

(J/g

)

TA00 TA01 TA03 TA05

Hydration heat at 23˚C (73˚F)

TA05

0

3

6

9

1 7 13 19 25Time (h)

Pow

er (

mW

/g)

TA00 TA01 TA03 TA05

Hydration rate at 38˚C (100˚F)

TA03

TA05

4011

018

025

032

039

0

1 10 19 28 37 46 55 64 73Time (h)

Ene

rgy

(J/g

)

TA00 TA01 TA03 TA05

Hydration heat at 38˚C (100˚F)

TA05

Example: cement and fly ash combination

Class-C

0

20

40

60

80

100

120

0 35 70 105 140Time (min)

Co

ns

iste

nc

y (

Bc

)-T

em

p (

°F)

0

1

2

3

4

5

6P

res

su

re (k

ps

i)

Consistency (Bc) Temperature(F) Pressure(kpsi)

Class-C+50% FA

6

10

14

18

22

26

0 20 40 60 80 100 120 140 160Time (min)

Co

ns

iste

nc

y (

Bc

)

0

1

2

3

4

5

Pre

ss

ure

(kp

si)

Consistency (Bc) Pressure(kpsi)

Well cement with 50% Class-C fly ash (C-FA)

Class-C+50% FA

0

20

40

60

80

100

120

0 44 88 132 176 220Time (min)

Co

ns

iste

nc

y (

Bc

)-T

em

p (

°F)

0

1

2

3

4

5

6

Pre

ss

ure

(kp

si)

Consistency (Bc) Temperature(F) Pressure(kpsi)

• Viscosity increase

Class-C+50% FA

6

10

14

18

22

26

0 20 40 60 80 100 120 140 160Time (min)

Co

ns

iste

nc

y (

Bc

)

0

1

2

3

4

5

Pre

ss

ure

(kp

si)

Consistency (Bc) Pressure(kpsi)

Well cement with 50% C-FA and 1.5% gypsum

Class-C+50% FA+1.5% Gypsum

0

20

40

60

80

100

120

0 46 92 138 184 230

Time (min)

Co

nsi

sten

cy (

Bc)

-T

emp

(°F

)

0

1

2

3

4

5

6

Pre

ss

ure

(kp

si)

Consistency (Bc) Temperature(F) Pressure(kpsi)

6

10

14

18

22

26

0 20 40 60 80 100 120 140 160Time (min)

Co

ns

iste

nc

y (

Bc

)

Class-C Class-C+50%FA Class-C+50%FA+1.5% gyp

Viscosity profile comparison

0

20

40

60

80

100

0 46 92 138 184 230Time (min)

Co

nsi

ste

ncy

(B

c)

Class-C Class-C+50%FA Class-C+50%FA+1.5% gyp

• Gypsum addition eliminates high viscosity during early stages

SO3: Supply - Demand Rule

SO3 supply

SO3 demand

fals

e

norm

al

fla

sh

If SO3 supply is greater than demandfa

lse

no

rmal

f

lash

SO3 supply SO3 demand

If SO3 supply is greater than demandfa

lse

no

rmal

f

lash

SO 3 supply

SO 3

demand

If SO3 supply is less than demandfa

lse

no

rmal

f

lash

SO3 supply SO3 demand

If SO3 supply is less than demandfa

lse

no

rmal

f

lash

SO3 supply

SO3 demand

• 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.

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