ASTM C1356-07(2020)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1356 − 07 (Reapproved 2020)
Standard Test Method for
Quantitative Determination of Phases in Portland Cement
Clinker by Microscopical Point-Count Procedure
This standard is issued under the fixed designation C1356; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Definitions of Terms Specific to This Standard:
3.2.1 clinker phase, n—a physically and chemically distinct
1.1 This test method covers a systematic procedure for
optically identifiable portion of the clinker sample, including
measuring the percentage volume of the phases in portland
both principal phases (alite, belite, aluminate, and ferrite),
cement clinker by microscopy.
minor phases (for example, free lime, periclase, and alkali
1.2 The values stated in SI units are to be regarded as the
sulfates), and voids.
standard.
3.2.1.1 Discussion—Voids, though not a phase in the sense
1.3 This standard does not purport to address all of the
of being a crystalline compound, are a distinct, identifiable
safety concerns, if any, associated with its use. It is the
portion of a clinker microstructure.
responsibility of the user of this standard to establish appro-
3.2.2 voids, n—isolated or interconnected open areas in the
priate safety, health, and environmental practices and deter-
clinker, also called pores.
mine the applicability of regulatory limitations prior to use.
3.3 Principal Clinker Phases:
1.4 This international standard was developed in accor-
3.3.1 alite, n—crystallinetricalciumsilicate(C S),modified
dance with internationally recognized principles on standard- 3
incompositionandcrystalstructurebyincorporationofforeign
ization established in the Decision on Principles for the
ions; the crystals are pseudo-hexagonal with well-defined
Development of International Standards, Guides and Recom-
faces, though less regular shapes commonly occur.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
3.3.2 aluminate, n—tricalcium aluminate (C A) modified in
composition and crystal structure by incorporation of a sub-
2. Referenced Documents
stantial proportion of foreign ions; aluminate forms cubic
2.1 ASTM Standards: crystals when relatively pure, and forms identifiable elongated
C150/C150MSpecification for Portland Cement crystals commonly called “alkali aluminate” when in solid
C219Terminology Relating to Hydraulic and Other Inor- solution with significant amounts of potassium or sodium, or
ganic Cements both.
C670Practice for Preparing Precision and Bias Statements
3.3.3 belite, n—crystalline dicalcium silicate (C S), modi-
for Test Methods for Construction Materials
fied in composition and crystal structure by incorporation of
D75/D75MPractice for Sampling Aggregates
foreign ions; belite usually occurs as rounded crystals marked
D3665Practice for Random Sampling of Construction Ma-
by striations formed by cross sections of lamellae, and may
terials
occur as single crystals or in clusters.
3.3.4 ferrite, n—a solid solution of approximate composi-
3. Terminology
tion tetracalcium aluminoferrite (C AF) modified in composi-
3.1 Definitions:
tion by variation in theAl/Fe ratio and by substantial incorpo-
3.1.1 For definitions of other terms relating to hydraulic
ration of foreign ions; ferrite is characterized by high
cements, refer to Terminology C219.
reflectivity in polished sections and is normally the only
strongly colored compound among the principal clinker
ThistestmethodisunderthejurisdictionofASTMCommitteeC01onCement
phases.
andisthedirectresponsibilityofSubcommitteeC01.23onCompositionalAnalysis.
3.3.4.1 Discussion—Aluminate and ferrite form most of the
Current edition approved Feb. 1, 2020. Published February 2020. Originally
interstitial material between the silicate crystals and, under
approved in 1996. Last previous edition approved in 2012 as C1356–07(2012).
DOI: 10.1520/C1356-07R20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
¯
Standards volume information, refer to the standard’s Document Summary page on C=CaO,S=SiO,A=Al O,F=Fe O,S=SO ,M=MgO,N=Na O,and
2 2 3 2 3 3 2
the ASTM website. K=K O in cement chemistry notation.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1356 − 07 (2020)
certain conditions of cooling, may not be easily identifiable or 6.2 Mechanical stage with stepping increments ranging
resolved by ordinary light microscopy. from0.05to2.0mm(toenableanalysisofclinkersofdifferent
average crystal sizes) and vernier scales graduated in both X
3.4 Minor Clinker Phases:
and Y directions.
3.4.1 alkali sulfates, n—sodium sulfate, potassium sulfate,
and double sulfates such as calcium langbeinite 6.3 Microscope objectives of magnification 5×, 10×, 20×,
(K SO –2CaSO ). and 40× or other magnifications suitable for the task.
2 4 4
3.4.2 free lime, n—calciumoxide(C)foundmostlyasround
NOTE 3—The use of reflected light with oil immersion is optional. It is
crystals. highly recommended for study of finely crystalline aluminate and ferrite
which typically form the ground mass in which the silicates occur.
3.4.3 periclase, n—crystalline form of free magnesium ox-
Reflected light objective lenses with magnification up to 100× designed
ide (M), that has not been taken up in solid solution with other
for use in oil-immersion are required.
phases.
6.4 Assorted eyepieces (5×, 10×, 20×) which when com-
bined with the objectives described in 6.3 will provide magni-
4. Summary of Test Method
fications up to 800×.
4.1 The test method consists of the preparation and micro-
6.5 Eyepiece reticles (graticulae) with a linear grid pattern
scopicalexaminationofaspecimenproducedbyencapsulating
containing 9, 16, or 25 intersections.
clinker in a mounting medium and sectioning the specimen so
as to expose the interior of particles for visual examination.
6.6 Eyepiece micrometer for measuring dimensions of the
Polishing the section surface and treating it with etchants to
object under investigation and calibrated for each magnifica-
highlight specific phases complete the preparation. During
tion.
microscopical examination phases are identified and their
6.7 Stage micrometer for the calibration of the eyepiece
proportions determined by a point-count procedure. In this
micrometer.
procedure, the specimen is moved in uniform increments on a
6.8 Light source that provides uniform and consistent illu-
microscope stage, and phases falling under the cross hairs of
mination of the field and light of constant intensity.
the eyepiece are identified and counted (1-5).
6.9 Counting (tallying) device capable of recording up to
5. Significance and Use
ten categories of data.
5.1 This test method provides a relatively simple and
6.10 Crushing device capable of reducing sample particle
reliable microscopical means of measuring the phase abun-
size to between 1 and 4 mm.
danceofportlandcementclinker(Note1).Microscopicalpoint
6.11 Riffle sample splitter to reduce sample from initial
counting provides a direct measure of the clinker phase
volume to approximately 100 g.
composition in contrast to the calculated Bogue phase compo-
sition (Note 2).
6.12 Wireclothsieveswithopeningssuitableforsievingthe
entire clinker sample to broadly define the model size class,
NOTE1—Thistestmethodutilizesareflectedlightmicroscope.Related
and sieves with 1- and 4-mm square openings to concentrate
methods such as transmitted light microscopy, scanning electron
microscopy, and automated imaging techniques may also be used for particles of recommended size for specimen preparation.
clinker analysis but are not presently included in this test method.
6.13 Vacuum impregnation device to force epoxy into
NOTE2—Thistestmethodallowsdirectdeterminationoftheproportion
clinker voids. (Vacuum bell jar or desiccator connected to a
of each individual phase in portland cement clinker. This test method is
intended to provide an alternative to the indirect estimation of phase
vacuum pump.)
proportion using the equations in Specification C150/C150M (footnote C
6.14 Curing oven, hot plate, slide warmer, or ultraviolet
in Table 1 and footnote B in Table 2).
light may be used to accelerate the epoxy hardening.
5.2 This test method assumes the operator is qualified to
6.15 Thin, diamond-rimmed wafering saw for sectioning
operate a reflected light microscope and the required
the encapsulated clinker.
accessories, is able to correctly prepare polished sections and
use necessary etchants, and is able to correctly identify the
6.16 Glass grinding (lapping) plates (300×300×5mm)
constituent phases.
required only if the mechanical system is not equipped to
handle the final grinding with alumina powder.
5.3 Thistestmethodmaybeusedaspartofaqualitycontrol
program in cement manufacturing as well as a troubleshooting
6.17 Ultrasonic cleaning device (optional) to clean the
tool. Microscopic characterization of clinker phases may also
sample prior to, between, and after polishing steps.
aidincorrelatingcementpropertiesandcementperformancein
7. Reagents and Materials
concrete, to the extent that properties and performance are a
function of phase composition.
7.1 Consumable grinding (lapping) and polishing supplies.
After the encapsulated specimen has been cut with the saw, all
6. Apparatus
or most of the following grinding and polishing steps are
6.1 Reflected light microscope.
required: 120-, 320-, and 600-grit silicon carbide grinding
papersorequivalentand5,0.3,and0.05µmaluminapolishing
powders or their equivalent. Diamond grinding discs, silicon
Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
this standard. carbide paper, or polishing cloths and alumina polishing
C1356 − 07 (2020)
powder may be used.Various types of polishing cloths may be 10.2 Choose the stepping interval such that an entirely
used to produce a nearly flat clinker surface or a relief surface different field of view is observed after each step.
to aid in identification of periclase (1).
10.3 Attach a mechanical stage to the microscope. The
7.2 Sample cups (with volumes ranging from 10 to 20 mL) mechanical stage may be an electrically driven specimen
to contain epoxy-clinker mix during hardening. carriage connected to an automatic electronic counter or a
simple hand-operated carriage and counter. Place a small
7.3 Epoxy resin and hardener for encapsulation of the
amountofsoftmodelingclayonastandard,petrographicglass
clinker. Low viscosity resin will facilitate penetration into
slide (27×46mm) and level the sample thereon. Either use a
clinker voids. When hardened it should have an abrasive
commercial leveling device or use a small spirit level to adjust
resistance close to that of the clinker to minimize relief during
the mount while pressing it firmly into the clay.Atissue paper
polishing.Itshouldberesistanttosubstancesusedforwashing
between the polished section and the leveling device or spirit
and etching.
level prevents surface scratches. Place the glass slide with
7.4 Isopropyl alcohol (2-propanol) for washing the speci-
attached clay and leveled mount on the mechanical stage.
men and for use in the ultrasonic cleaner. Propylene glycol is
Check the accuracy of leveling by observing the focus at
suitable as a lubricant for the saw blade.
severalpointsonthepolishedsurface.Movetoastartingpoint
(the initial field of view from which data will be taken) at the
7.5 Immersion oil with an index of refraction of 1.51 if
reflected light immersion-oil technique is used. edge of the mount and record the position in the X-Y
coordinate system, using the graduated scales on the mechani-
7.6 Etching material to highlight different phases for count-
cal stage.
ing (see Appendix X3).
10.4 Use a tally sheet or a counting device to record the
8. Sampling
phasesasrequired.Theobservershouldnotkeepamentaltally
of any data because of possible bias. Identify and record each
8.1 Take samples of portland cement clinker in accordance
phaseunderthegridintersections.Insomecases,thealuminate
with the applicable provisions of Practices D75/D75M and
and ferrite quantities may be combined and labeled “matrix”.
D3665 so as to be representative of the quantity of material
Move the mechanical stage a distance of one stepping interval
with which testing is concerned (see Appendix X1).
in the chosen X orYdirection to bring another field into view.
8.2 Sieve the initial sample to obtain clinker particles
The phases under the grid points are identified, counted, and
representing approximately 70% of the clinker particle size
the mechanical stage advanced one stepping interval to an
distribution, centered about the mode. This particle size inter-
adjacentfieldofview.Thisprocedureiscontinueduntilarange
val represents a size range of approximately two standard
of 3000 to 4000 points are recorded.
deviations,oneoneachsideofthemode,andishereindefined
At the clinker periphery, some of the reticle points may fall
as the “bulk mode” (M ), the combined material between the
b
on the encapsulating epoxy that surrounds the clinker particle.
extremes of the particle size distribution. State the sieve sizes
Count only points within the clinker, and disregard the reticle
used. If either extreme of the particle size distribution is to be
points over epoxy at the clinker periphery. Thus, the clinker
studied, the selected portion shall be identified as non-modal,
voidspace(porosity),ifdeterminedinthepointcount,doesnot
andthepercentagesretainedorpassingstandardsievesshallbe
include cavities on the surface of the clinker particle. As one
stated. The recommended size fraction for microscopical
stepsoverirrelevantareas(suchasepoxyexteriortotheclinker
analysis is 2 to 4 mm. Therefore, that portion of the initial
or severally damaged portions of the polished surface that
clinker sample representing the bulk mode shall be crushed,
obscure the phase identification) the count is temporarily
sieved, and riffled to provide approximately 100 g. Whole
suspended until a suitable clinker surface again falls under the
clinkers may be encapsulated to study the phase distribution
reticle grid points.Artifacts (for example, blot marks, residual
within clinker nodules.
liquids) on the section surface are not to be counted. If the
ident
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