Tests on Portland Cement
Dr. Kimberly Kurtis
School of Civil Engineering
Georgia Institute of Technology
Atlanta, Georgia
Composition
Chemical Formula
Shorthand
Notation
Mass
(%)
Tricalcium silicate
3CaO•SiO2
C3S
50 - 70
Dicalcium silicate
2CaO• SiO2
C2S
15 - 30
Tricalcium aluminate
3CaO•Al2O3
C3A
5 - 10
4CaO•Al2O3•Fe2O3
C4AF
5 - 15
CaSO4•2H2O
CSH2
~5
Chemical Name
Tetracalcium aluminoferrite
Calcium sulfate dihydrate
1
Composition
The relative quantities of each of these phases affects:
• setting time
• rate of strength development
• overall strength
• durability
• color
It is important, then, to know the composition of the
cement.
Tests on Portland, Blended & Hydraulic Cements
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
2
Belite, C2S
Alite, C3S
Width of field = 0.31 mm
3
/
http://www.bruker-axs.de
Chemical Analysis
SiO2
Silicon dioxide
Al2O3
Aluminum oxide
Fe2O3
Ferric oxide
CaO
Calcium oxide
MgO
Magnesium oxide
SO3
Sulfur trioxide
LOI
Loss on ignition
Na2O
Sodium oxide
K2O
Potassium oxide
TiO2
Titanium dioxide
P2O5
Phosphorus pentoxide
ZnO
Zinc oxide
Mn2O3
Manganic oxide
ASTM C 114 Standard Test
Methods for Chemical Analysis
of Hydraulic Cement
Major components
Separate determinations
•
Insoluble residue
•
Free calcium oxide
•
CO2 (carbon dioxide)
•
Water-soluble alkali
•
Chloroform – soluble organic
substances
Minor components
Sulfide sulfur
4
ASTM C114
Oxide Analysis
Oxide
%
SiO2
20.6
Al2O3
5.07
90 – 95%
Oxide
Shorthand
Common Name
CaO
C
lime
SiO2
S
silica
Al2O3
A
alumina
Fe2O3
F
ferric oxide
MgO
M
magnesia
Fe2O3
2.90
CaO
63.9
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
+ other trace elements
alkalis
Compound Composition
Bogue Composition
C3S = 4.07C – 7.60S – 6.72A – 1.43F – 2.85S
C2S = 2.87S – 0.75C3S
C3A = 2.65A – 1.69F
C4AF = 3.04F
(Only valid when A/F ≥ 0.64)
5
Bogue Composition: Example
Oxide Analysis
Calculated Phase Composition
Oxide
%
SiO2
20.6
Al2O3
5.07
Fe2O3
2.90
CaO
63.9
MgO
1.53
K2O
0.73
C4AF = 3.04(2.90) = 8.8
Na2O
0.15
Bogue Potential Composition:
SO3
LOI
C3S = 4.07(63.9) – 7.60(20.6) – 6.72(5.07)
– 1.43(2.90) - 2.85(2.53) = 58.1
C2S = 2.87(20.6) – 0.754(58.1) = 15.6
C3A = 2.65(5.07) – 1.69(F 2.90) = 8.5
C3S
58%
2.53
C2S
16%
1.58
C3A
9%
C4AF
9%
Typical Chemical Composition of Portland Cement
Oxide Analysis
Oxide
%
Sodium equivalent, Na2Oe
SiO2
20.6
Al2O3
5.07
Fe2O3
2.90
CaO
63.9
MgO
1.53
K2O
0.73
Na2O
0.15
SO3
2.53
LOI
1.58
Na2Oe = Na2O + (0.658 x K2O)
Na2Oe = 0.15 + (0.658 x 0.73)
Na2Oe = 0.63%
+ other trace elements
6
Bogue Composition
The Bogue equations are based on the following assumptions:
1) All 4 phases are pure
2) All the F present occurs as C4AF, 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 C3A 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 result, Bogue compositions may be “off” by as much as
10% compared to XRD-determined compositions.
Bogue
XRD
7
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
SO3, max. %
C3A ≤ 8%
C3A > 8%
3.0
3.5
3.0
n/a
3.5
4.5
2.3
n/a
3.0
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
Chemical Limits
ASTM C 150 Portland Cement - Chemical Requirements
Cement Type
I
II
III
IV
V
C3S, max. %
-
-
-
35
-
C2S, min. %
-
-
-
25
-
C3A, max. %
-
8
15
7
5
C4AF + 2 C3A,
max. %
-
-
-
-
25
8
Chemical Limits
ASTM C 150 Portland Cement – Optional Chemical Requirements
Cement Type
I
II
III
IV
V
C3A, max. %
-
-
8
-
-
C3A, max. %
-
-
5
-
-
C33 + C3A, 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
-
-
6.0
Sulfur reported as SO3, 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*
-
MgO, max. %
Water-soluble alkali, max. %
*Only
required when cement is specified to be nonstaining to limestone
9
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
10
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 m2/kg
11
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 [(ε3Ah1)/(KLh2)]0.5
ρ(1-ε)
Blaine Air 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
12
Wagner Turbidimeter
•
•
•
Wagner Turbidimeter
(ASTM C 115)
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)
Blaine, in general, is 1.8X Wagner
Laser Particle Size Analyzer
•Laser particle size
analyzer
•Particle-size distribution
(psd)
13
Cement 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
14
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,
blended & hydraulic cements
≤ 0.80%
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
15
Setting Time
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
Setting Time
Vicat Needle
Gillmore Needles
ASTM C 150 Portland Cement
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 Blended Cement
Initial Set, not less than (h:min)
0:45
Final Set, not more than (h:min)
7:00
ASTM C 1157 Hydraulic Cement
Initial Set, not less than (h:min)
0:45
Final Set, not more than (h:min)
7:00
Setting Time
Type I
Initial
Final
Type II
Type III
Type IV
Type V
0
100
200
300
400
Time of Set (Minutes) - Vicat Method
18
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
Flash Set
•
Loss of plasticity shortly after mixing – little heat
•
Due to hemihydrate (Plaster) in cement –
hydrating to Gypsum
•
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
19
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 Strength Requirements, MPa (psi)
Age
Cement Type
I
II
III
IV
V
1 day
-
-
12.0
(1740)
-
-
3 days
12.0
(1740)
10.0
(1450)
24.0
(3480)
-
8.0
(1160)
7 days
19.0
(2760)
17.0
(2470)
-
7.0
(1020)
15.0
(2180)
28 days
-
-
-
17.0
(2470)
21.0
(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 Strength Requirements, MPa (psi)
Age
Cement Type
I(SM), IS,
I(PM), IP
IS(MS),
IP(MS)
S
P
3 days
13.0
(1890)
11.0
(1600)
-
-
7 days
20.0
(2900)
18.0
(2610)
5.0
(720)
11.0
(1600)
28 days
25.0
(362)
25.0
(3620)
11.0
(1600)
21.0
(3140)
Lower strengths permitted for air-entraining cements (with suffix –A)
21
Compressive Strength
ASTM C 1157 Standard Specification for Hydraulic Cement
Minimum Strength 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 Strength Requirements (MPa)
Strength Range
5
10
17
25
35
45
Minimum Strength,
MPa (psi)
5
(725)
10
(1450)
17
(2465)
25
(3625)
35
(5075)
45
(6525)
Maximum Strength,
MPa (psi)
15
(2175)
20
(2900)
30
(4350)
40
(5800)
60
(8700)
-
22
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
23
Heat of Hydration
Moderate Heat
of Hydration
ASTM C 150
Portland Cement
Low Heat of
Hydration
Type II (Option)
Type IV
290 kJ/kg at 7 days
250 kJ/kg at 7 days
290 kJ/kg at 28 days
Heat of Hydration
Moderate Heat
of Hydration
ASTM C 150
Portland Cement
Low Heat of
Hydration
Type II (Option)
Type IV
290 kJ/kg at 7 days
250 kJ/kg at 7 days
290 kJ/kg at 28 days
ASTM C 595
Blended Cement
Suffix -MH
Suffix -LH
290 kJ/kg at 7 days
250 kJ/kg at 7 days
330 kJ/kg at 28 days
290 kJ/kg at 28 days
24
Heat of Hydration
Moderate Heat
of Hydration
ASTM C 150
Portland Cement
Low Heat of
Hydration
Type II (Option)
Type IV
290 kJ/kg at 7 days
250 kJ/kg at 7 days
290 kJ/kg at 28 days
ASTM C 595
Blended Cement
ASTM C 1157
Hydraulic Cement
Suffix -MH
Suffix -LH
290 kJ/kg at 7 days
250 kJ/kg at 7 days
330 kJ/kg at 28 days
290 kJ/kg at 28 days
Type MH
Type LH
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).
26
Sulfate Expansion
ASTM C 452 Standard Test Method for 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 C3A, C4AF
+ 2C3A, SiO2 & Fe2O3
not required
27