Geoscience Reference
In-Depth Information
Table 18
Summary of American classification of Portland cement types
ASTM C150 cement type
Cement description
Ty p e
Ι
Normal Portland cement
Ty p e
ΙΙ
Modified cement
Ty p e
ΙΙΙ
Rapid hardening Portland cement
Ty p e
Ι
V
Low heat Portland cement
Type V
Sulfate-resisting cement
ASTM C595 cement type
Blended cement description
Ty p e
Ι
S
Portland blastfurnace slag cement
Ty p e
Ι
P
Portland-pozzolan cement
Type P
Portland-pozzolan cement for use when higher strengths at early ages are not required
Ty p e
Ι
(PM)
Pozzolan-modified Portland cement
Ty p e
Ι
(SM)
Slag-modified Portland cement
Type S
Slag cement
Table 19
Properties of the principal components of cement clinker
Property
Component
Mineral
Tricalcium silicate
Dicalcium silicate
Tricalcium aluminate
Tetracalcium
(alite)
(belite)
(aluminate)
aluminoferrite
(brownmillerite
or ferrite)
Abbreviated cement
C
3
S
C
2
S
C
3
A
C
4
AF
chemists' formula
Full chemical formula
3CaO.SiO
2
2CaO.SiO
2
3CaO.Al
2
O
3
4CaO.Al
2
O
3
.Fe
2
O
3
Typical proportion
55-65
15-25
8-14
8-12
in cement (wt %)
Relief
High
High
High
Very high
Colour in PPT light
Colourless to
Colourless, yellow,
Brown in Portland
Brown to yellow.
slightly coloured
or green
cement and colourless
Pleochroic, green
in white cement
to almost opaque
Birefringence
First-order grey
Second-order
None to low
First-order white
interference colours
interference colours
to yellow
Form
Lath, tablet-like or
Rounded grains,
Usually cubic form
Bladed, prismatic,
equant. Six sided in
often clustered
filling spaces between
dendritic, fibrous,
cross-section.
belite and ferrite
massive or infilling
25-65 μm in size
crystals
Extinction and
Wavy to straight,
Lamellar
May have oblique,
Crystals exhibit
twinning
length slow
twinning
length slow
length slow
extinction.
common
extinction. Twinning
extinction
Rare polysynthetic
may be present
twinning
Colour in reflected
Does not etch
Does not etch
Bluish-grey
White
light after etching
with KOH solution
Colour in reflected
Buff brown
Blue
Light grey
White
light after etching
with HF vapour
