Tests on Portland Cement.pdf

Tests on Portland Cement Dr. Kimberly Kurtis School of Civil Engineering Georgia Institute of Technology  Atlanta, Georgia

Composition Chemical Formula

Shorthand Notation

Mass (%)

Tricalcium Tricalcium silicate silicate

3CaO•SiO2

C3S

50 - 70

Dicalcium Dicalcium silicate silicate

2CaO 2CaO•• SiO SiO2

C2S

15 - 30

Tricalcium Tricalcium aluminate aluminate

3CaO•Al2O3

C3 A

5 - 10

4CaO•Al2O3•Fe2O3

C4 AF

5 - 15

CaSO4•2H2O

CSH2

~5

Chemical Name

Tetracalciu Tetracalcium m aluminoferr aluminoferrite ite Calcium sulfate dihydrate

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Composition The relative quantities of each of these phases affects: • settin setting g time time • rate of of strength strength development development • overall overall strengt strength h • durabi durabilit lity y • color  olor 

It is important, then, to know the composition of the cement.

Tests Tests on Portland, Hydraulic Cements Cements Portl and, Blended Blended & Hydraulic Blended Chemical Chemical Properties

Physical Properties

Chemical analysis

Fineness

Compound composition

Soundness

Chemical limits

Consistency Setting time False set and flash set Compressive strength Heat of hydration Loss on ignition Density Bulk density Sulfate expansion

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Belite, C2S

Alite, C3S

Width o f field = 0.31 mm

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http://www.bruker-axs.de

Chemical Analys Analysiiss SiO2

Silicon dioxide

 Al2O3

 Aluminum oxide

 ASTM C 114 Standard Test Methods for Chemical Analysis of Hydraulic Cement

Fe2O3

Ferric oxide

CaO

Calcium oxide

MgO

Magnesium oxide

Separate determinations

SO3

Sulfur trioxide

•

Insoluble residue

LOI

Loss on ignition

•

Free calcium oxide

Na2O

Sodium oxide

•

CO2 (carbon dioxide)

K2O

Potassium oxide

•

Water-soluble alkali

•

TiO2

Titanium dioxide

Chloroform – soluble organic substances

P2O5

Phosphorus pentoxide

ZnO

Zinc oxide

Mn2O3

Manganic oxide

Major components

Minor components

Sulfide sulfur 

4

 ASTM C114 Oxide Analysis Oxide

Oxide

%

Shorthand

Common Name

CaO

C

lime silica

SiO2

20.6

SiO2

S

 Al2O3

5.07

 Al2O3

 A

Fe2O3

2.90

Fe2O3

F

ferric oxide

CaO

63.9

MgO

M

magnesia

MgO

1.53

K2O

0.73

K2O

K

Na2O

0.15

Na2O

N

SO3

2.53

SO3

S

sulfate

LOI

1.58

CO2

C

carbonate

H2O

H

water

90 – 95%

+ other tr ace elements

alumina

alkalis

 

Compound Composition

Bogue Composition

C3S = 4.07C – 7.60S – 6.72A – 1.43F – 2.85S C2S = 2.87S – 0.75C3S C3 A = 2.65A – 1.69F C4 AF = 3.04F (Only valid when A/F ≥ 0.64)

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Bogue Composition: Example Oxide Analysis Oxide

%

Calculated Phase Composition C3S = 4.07(63.9) – 7.60(20.6) – 6.72(5.07)

 – 1.43(2.90) - 2.85(2.53) = 58.1 SiO2

20.6

 Al2O3

5.07

Fe2O3

2.90

CaO

63.9

MgO

1.53

K2O

0.73

C4 AF = 3.04(2.90) = 8.8

Na2O

0.15

Bogue Potential Composition:

SO3 LOI

C2S = 2.87(20.6) – 0.754(58.1) = 15.6 C3 A = 2.65(5.07) – 1.69(F 2.90) = 8.5

C3S

58%

2.53

C2S

16%

1.58

C3 A

9%

C4 AF

9%

Typical Chemical Composition of Portland Cement Oxide Analysis Oxide

%

Sodium equiv alent, Na2Oe SiO2

20.6

 Al2O3

5.07

Fe2O3

2.90

CaO

63.9

MgO

1.53

K 2O

0.73

Na2O

0.15

SO3

2.53

LOI

1.58

Na2Oe = Na2O + (0.658 x K 2O)

Na2Oe = 0.15 + (0.658 x 0.73) Na2Oe = 0.63%

+ other tr ace elements

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Bogue Composition The Bogue equations are based on the following assumptions: 1) All 4 phases are pure 2) All the F present occurs as C4 AF, and the quantities of A = 0.64(%F) and C = 1.40 (%F) are subtracted from the appropriate totals. 3) The remaining Al2O3 is combined as C3 A and a further quantity of C = 1.65 (% Al2O3) is subtracted fromt eh total remaining CaO. 4) The SiO2 combines initially with CaO to form C2S giving a provisional C2S figure. The CaO combining with SiO2 = 2.87%(SiO2) is subtracted from the total CaO figure, and the remaining CaO is then combined with a part of the C2S = 4.07(%CaO) to form C3S.  As a resul t, Bogue composi ti ons m ay be “ of f” by as muc h as 10% compared to XRD-determined compositions.

Bogue

XRD

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Chemical Limits  ASTM C 150 Portland Cement - Chemical Requirements Cement Type I

II

III

IV

V

SiO2, min. %

-

20.0

-

-

-

 Al2O3, max. %

-

6.0

-

-

-

Fe2O3, max. %

-

6.0

-

6.5

-

MgO, max. %

6.0

6.0

6.0

6.0

6.0

C3 A ≤ 8%

3.0

3.0

3.5

2.3

3.0

C3 A > 8%

3.5

n/a

4.5

n/a

n/a

LOI, max. %

3.0

3.0

3.0

2.5

3.0

Insoluble residue, max. %

0.75

0.75

0.75

0.75

0.75

SO3, max. %

Chemical Limits  ASTM C 150 Portland Cement - Chemical Requirements Cement Type I

II

III

IV

V

C3S, max. %

-

-

-

35

-

C2S, min. %

-

-

-

25

-

C3 A, max. %

-

8

15

7

5

C4 AF + 2 C3 A, max. %

-

-

-

-

25

8

Chemical Limits  ASTM C 150 Portland Cement – Optional Chemical Requirements Cement Type I

II

III

IV

V

C3 A, max. %

-

-

8

-

-

C3 A, max. %

-

-

5

-

-

C33 + C3 A, max. %

-

58

-

-

-

0.60

0.60

0.60

0.60

0.60

Na2Oe, max. %

Chemical Limits  ASTM C 595 Blended Cement - Chemical Requirements Cement Type I(SM), I(SM) A, IS, IS-A

S, SA

I(PM), I(PM)-A, P, PA, IP, IP-A

MgO, max. %

-

-

6.0

Sulfur reported as SO 3, max. %

3.0

4.0

4.0

Sulfide sulfur (S), max. %

2.0

2.0

-

Insoluble residue, max. %

1.0

1.0

-

LOI, max. %

3.0

4.0

5.0

-

0.03*

-

Water-soluble alkali, max. % *Only

required when cement is specified to be nonstaining to limestone

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Fineness Fineness of cement is also important; it affects: • •

rate of hydration rate of setting

•

rate of hardening

•

durability (ASR)

•

rate of carbonation during storage

•

cost

•

rate of gypsum addition

•

bleeding

Fineness However, later strength is not directly affected.

Neville, Fig. 1.5

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Fineness  Approx. 95% ≤ 45 microns  Average diameter ~ 15 microns Those retained on the No 200 sieve (75 microns) will never hydrate completely Those retained on the No 325 sieve (45 microns) will be difficult to hydrate completely Type III >> Type I, II, V > Type IV

Fineness is generally described as the specific surface of the cement, which is the surface area expressed in m 2/kg

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Lea and Nurse Air Permeability Relates flow of fluid (air) through a bed of granular material (cement) to the specific surface area of that granular material By knowing ρcement, a bed 10mm thick with porosity of 4.75% is made; air is passed through at constant velocity; pressure drop is measured. Sw= 14 [(ε3 Ah1)/(KLh2)]0.5 ρ(1-ε)

Blaine Air Permeabili ty Permeability

• With the Lea Nurse method, air passes through the bed at a constant rate

Blaine Air Permeability (ASTM C 204)

• In the Blaine test, a known volume of air passes at a constant pressure through the bed • The rate of flow decreases steadily • The time for flow to occur is measured for a given apparatus and a standard porosity of 5% (0.500). Sw = K2t0.5

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Wagner Turbidimeter  •

•

• Wagner Turbidimeter 

Uses a photoelectric cell to measure light passing through cement particles suspended in kerosene Test is based on Stoke’s Law that states that a sphere will obtain a constant velocity under the action of gravity Allows calculation of particlesize distribution (psd)

(ASTM C 115) Blaine, in general, is 1.8X Wagner 

Laser Partic Particlle e Size Analyzer 

•Laser particle size analyzer  •Particle-size distribution (psd)

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Cement Fin eness Fineness

 ASTM C 430 •

Sample washed over 45-µm (# 325) sieve

•

Used in production

•

Limits for pozzolans and slag (ASTM C 595)

Cement Fineness Requirements for Type I, II, IV & V (No requirements for Type III)  Air Permeability Turbidimeter   ASTM C 150 &  AASHTO M 85

280

160

Maximum, m2/kg AASHTO M 85

400

220

Typical values, m2/kg

350-380 Type I

Minimum, m2/kg

450-600 Type III No limits for blended cement (ASTM C 595) or hydraulic cements (ASTM C 1157) but values must be reported on mill test reports

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Soundness

Soundness

- ability of hardened paste to maintain volume after setting

Unsoundness (abnormal expansion) caused by hard-burned CaO or MgO

CaO +  H 2O → Ca(OH ) 2  MgO +  H 2O →  Mg (OH ) 2  ASTM C 151 Standard Test Method for  Autoclave Expansion of Portland Cement Expansion for all portland,

≤ 0.80%

blended & hydraulic cements

Consistency Consistency of Cement Paste •

Penetration of 10 ± 1 mm of Vicat plunger 

•

ASTM C 187 Standard Test Method for Normal Consistency of Hydraulic Cement

Consistency of Mortar  •

Flow table

•

ASTM C 1437 Standard Test Method for Flow of Hydraulic Mortar 

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Settin g Time Setting

Initial Set

Time from moment water is added until the paste ceases to be fluid and plastic

Final Set

Time from moment water is added for the paste to acquire a certain degree of hardness

Setting Time: Standard Test

Vicat Needle •

ASTM C 191 Standard Test Method for Time of Setting of Hydraulic Cement by Vicat Needle

•

Initial set occurs when needle penetrates - after 30s - 25 mm (1 inch) into paste

•

Final set occurs when there is no visible penetration

16

Setting Time: Field Measurements •

Concrete penetrometer, measures resistance to penetration in sieved mortar samples

•

Pocket penetrometers

Setting Time: Standard Test

Gillmore Needles •

ASTM C 266 Standard Test Method for Time of Setting of Hydraulic-Cement Paste by Gillmore Needles

•

Setting determined as time when paste resists indentation by needles

17

Settin g Time Setting Vicat Needle

Gillmore Needles

 ASTM C 150 Por tl and Cemen t

Initial Set, not less than (h:min)

0:45

1:00

Final Set, not more than (h:min)

6:15

10:00

 ASTM C 595 Bl end ed Cemen t

Initial Set, not less than (h:min)

0:45

Final Set, not more than (h:min)

7:00

 ASTM C 1157 Hyd rau li c Cem ent

Initial Set, not less than (h:min)

0:45

Final Set, not more than (h:min)

7:00

Settin g Time Setting

Type I Initial

Type II

Final Type III Type IV Type V 0

100

200

300

400

Time of Set (Minutes) - Vicat Method

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False Set and Flash Set “ Early Stiffening”

False Set

•

Loss of plasticity shortly after mixing – little heat

•

Due to hemihydrate (plaster) in cement –  hydrating to gypsum

•

Workability restored by additional mixing

False Set and Flash Set “ Early Stiffening”

False Set

•

Loss of plasticity shortly after mixing – little heat

•

Due to hemihydrate (Plaster) in cement –  hydrating to Gypsum

Flash Set

•

Workability restored by additional mixing

•

Rapid & early loss of workability – significant heat

•

Due to rapid reaction of aluminates – when insufficient sulfate present

•

Workability cannot be restored

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Compressive Strength

 ASTM C 109 Standard Test Method for Compressive Strength of Hydraulic Cement Mortars. •

50-mm (2-inch) mortar cubes

•

Sand:Cement = 2.75:1

•

Water/Cement = 0.485 for portland cement (0.460 for air-entraining portland cement)

•

Sufficient water for flow 110 ± 5 for blended (ASTM C 595) and hydraulic (ASTM C 1157) cements

20

Compressive Strength  ASTM C 150 Standard Specification for Portland Cement Minimum Str ength Requirements, MPa (psi)  Age

1 day

Cement Type I

II

III

IV

V

-

-

12.0

-

-

-

8.0

(1740) 3 days 7 days 28 days

12.0

10.0

24.0

(1740)

(1450)

(3480)

19.0

17.0

-

(2760)

(2470)

-

-

(1160) 7.0

15.0

(1020)

(2180)

17.0

21.0

(2470)

(3050)

-

Lower strengths permitted for air-entraining cements (Types IA, IIA & IIIA) and when heat of hydration option is specified for Type II cement

Compressive Strength  ASTM C 595 Standard Specification for Blended Hydraulic Cements Minimum Str ength Requirements, MPa (psi)  Age

3 days 7 days 28 days

Cement Type I(SM), IS, I(PM), IP

IS(MS), IP(MS)

S

P

13.0

11.0

-

-

(1890)

(1600)

20.0

18.0

5.0

11.0

(2900)

(2610)

(720)

(1600)

25.0

25.0

11.0

21.0

(362)

(3620)

(1600)

(3140)

Lower strengths permitted for air-entraining cements (with suffix –A)

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Compressive Strength  ASTM C 1157 Standard Specification for Hydraulic Cement Minimum Str ength Requirements (MPa)  Age

Cement Type GU

HE

MS

HS

MH

LH

1 day

-

10

-

-

-

-

3 days

10

17

10

5

5

-

7 days

17

-

17

10

10

5

28 days

-

-

-

17

-

17

Compressive Strength  ASTM C 1157 Standard Specification for Hydraulic Cement Minimum Str ength Requirements (MPa) Strength Range

5

10

17

25

35

45

Minimum Strength, MPa (psi)

5

10

17

25

35

45

(725)

(1450)

(2465)

(3625)

(5075)

(6525)

15

20

30

40

60

-

(2175)

(2900)

(4350)

(5800)

(8700)

Maximum Strength, MPa (psi)

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Heat of Hydration

Heat evolution in portland cement – tested by conduction calorimetry

Heat of Hydration Heat of Solution Test  ASTM C 186 Standard Test Method for Heat of Hydration of Portland Cement

Conduction Calorimetry

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Heat of Hydration Moderate Heat

Low Heat of

of Hydration

Hydration

 ASTM C 150

Type II (Option)

Type IV

Portland Cement

290 kJ/kg at 7 days

250 kJ/kg at 7 days 290 kJ/kg at 28 days

Heat of Hydration Moderate Heat

Low Heat of

of Hydration

Hydration

 ASTM C 150

Type II (Option)

Type IV

Portland Cement

290 kJ/kg at 7 days

250 kJ/kg at 7 days 290 kJ/kg at 28 days

 ASTM C 595

Suffix -MH

Suffix -LH

Blended Cement

290 kJ/kg at 7 days

250 kJ/kg at 7 days

330 kJ/kg at 28 days

290 kJ/kg at 28 days

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Heat of Hydration Moderate Heat

Low Heat of

of Hydration

Hydration

 ASTM C 150

Type II (Option)

Type IV

Portland Cement

290 kJ/kg at 7 days

250 kJ/kg at 7 days 290 kJ/kg at 28 days

 ASTM C 595

Suffix -MH

Suffix -LH

Blended Cement

290 kJ/kg at 7 days

250 kJ/kg at 7 days

330 kJ/kg at 28 days

290 kJ/kg at 28 days

 ASTM C 1157

Type MH

Type LH

Hydraulic Cement

290 kJ/kg at 7 days

250 kJ/kg at 7 days 290 kJ/kg at 28 days

Loss on Ignition  ASTM C 114 Standard Test Methods for Chemical Analysis of Hydraulic Cement •

Loss on ignition – LOI

•

Sample ignited at 900 to 1000°C (1650 to 1830°F)

•

High LOI indicates prehydration and/or carbonation

•

Improper or prolonged storage (transportation)

 ASTM C 150 Portland Cement

LOI ≤ 3.0% (2.5% for Type IV)

 ASTM C 595 Blended Cement

LOI ≤ 3.0 – 5.0%

 ASTM C 1157 Hydraulic Cement

No limit – must be reported

25

Density Le Chatelier flask - ASTM C 188 Standard Test Method for Density of Hydraulic Cement •

Range= 3100 to 3250 kg/m3

•

Average = 3150 kg/m3 (196 lb/ft3)

•

Not indicator of quality

•

Used for mixture proportioning calculations

Relative density (specific gravity) = 3.15

Helium pycnometer 

Bulk Density

Bulk density of cement varies between 830 kg/m3 (52 lb/ft3) and 1650 kg/m3 (103 lb/ft3).

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Sulfate Expansion

 ASTM C 452 Standard Test Method f or Potential Expansion of Portland-Cement Mortars Exposed to Sulfate •

Gypsum added to cement to yield 7.0% SO3 (by mass of cement + gypsum)

•

Mortar bars stored in water

•

Length change monitored periodically

•

Only applicable to portland cements

 ASTM C 150 Portland Cement Optional requirement for Type V Sulfate-Resisting Portland Cement

Expansion ≤ 0.040% at 14 days

Limits for C3 A, C4 AF + 2C3 A, SiO2 & Fe2O3 not required

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