ASTM D4124-97

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Designation: D 4124 – 97
Standard Test Methods for
Separation of Asphalt into Four Fractions
This standard is issued under the fixed designation D 4124; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope desorbed by toluene, after removal of the saturates under the
conditions specified.
1.1 These test methods cover the separation of four defined
3.1.3 petrolenes—the n-heptane-soluble matter recovered
fractions from petroleum asphalts. The four fractions are
following separation of the asphaltenes from the digested
defined as saturates, naphthene aromatics, polar aromatics, and
mixture under the specified conditions in these test methods.
nC -asphaltenes. These methods can also be used to isolate
3.1.4 polar aromatics—material desorbed from calcined
saturates, naphthene aromatics, and polar aromatics from
F-20 alumina absorbent, after the saturates and naphthene
distillate products such as vacuum gas oils, lubricating oils, and
aromatics have been removed, using toluene and trichloroeth-
cycle stocks. These distillate products usually do not contain
ylene eluants under the conditions specified.
asphaltenes.
3.1.5 saturates—material that, on percolation in a n-heptane
1.2 The values stated in SI units are to be regarded as the
eluant, is not absorbed on calcined F-20 alumina absorbent
standard.
under the conditions specified.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
METHOD A
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Test Method
bility of regulatory limitations prior to use. Specific precau-
4.1 The sample containing the four defined fractions is first
tionary statements are given in Section 8 and 15.
separated into n-heptane-insoluble asphaltenes and the
n-heptane-soluble petrolenes. Petrolenes are then adsorbed on
2. Referenced Documents
calcined F-20 alumina and further fractionated into the satu-
2.1 ASTM Standards:
rate, naphthene aromatic and polar aromatic fractions by
C 670 Practice for Preparing Precision and Bias Statements
downward solvent elution in a glass chromatographic column.
for Test Methods for Construction Materials
Eluted fractions are recovered by solvent removal prior to final
C 802 Practice for Conducting an Interlaboratory Test Pro-
weighing. The three eluted fractions plus the n-heptane-
gram to Determine the Precision of Test Methods for
precipitated (nC ) asphaltenes comprise the four fractions
2 7
Construction Materials
defined in Section 3.
D 140 Practice for Sampling Bituminous Materials
D 3279 Test Method for n-Heptane Insolubles
5. Significance and Use
2.2 Other Documents:
5.1 This test method separates asphalts into four well-
Manual on Hydrocarbon Analysis
defined fractions. Analysis of these fractions can be used to
evaluate asphalt composition. For example, one can compare
3. Terminology
the ratios of the fractions with other asphalt systems to evaluate
3.1 Definitions of Terms Specific to This Standard:
processing and aging parameters that relate to performance
3.1.1 asphaltenes or n-heptane insolubles—insoluble mat-
properties of the asphalt.
ter that can be separated from asphalt following digestion of
the asphalt in n-heptane under the specified conditions in these
6. Apparatus and Materials
test methods.
6.1 Glass Chromatographic Column, 1000 mm long and
3.1.2 naphthene aromatics—material that is adsorbed on
31 mm in inside diameter with features as specified in Fig. 1.
calcined F-20 alumina in the presence of n-heptane, and
6.2 Utilities—Steam bath, vacuum source, nitrogen source,
and drying oven (Rotavapor solvent stripper and electric
This test method is under the jurisdiction of ASTM Committee D-4 on Road
heating mantles optional).
and Paving Materials and is the direct responsibility of Subcommittee D04.47 in
6.3 Beakers, graduated; Erlenmeyer flasks, 400-mL; Round-
Miscellaneous Asphalt Tests.
Bottom Flasks, 500-mL, if Rotavapor is used for solvent
Current edition approved Aug. 10, 1997. Published April 1998. Originally
published as D 4124 – 82. Last previous edition D 4124 – 91.
removal.
Annual Book of ASTM Standards, Vol 04.02.
Annual Book of ASTM Standards, Vol 04.03.
4 5
Available from ASTM as PCN 03-332030-12. Can be custom-made by any professional glassblower.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 4124
FIG. 1 Chromatographic Column for Separation of Asphalt by Elution-Adsorption (Method A or B)
6.4 Funnels, two, pressure-equalizing, 500-mL. 6.11 Analytical Balance.
6.5 Funnel, Büchner, 12.5-cm.
6.12 Filter Paper, slow to medium filter speed, qualitative
6.6 Funnel, Separatory, 1-L, TFE-fluorocarbon stopcock
grade, 12.5-cm diameter.
preferred.
6.13 Extraction Thimble, 33/94 mm.
6.7 Flask, Suction, 2-L.
6.14 Stirrer, air-powered.
6.8 Flask, Erlenmeyer, 2-L, with foil-covered rubber stop-
6.15 Stirring Rod with suitable foil-covered rubber stopper
per.
to fit 2-L Erlenmeyer flask.
6.9 Rinse Squeeze Bottle, 0.5 L size, polyethylene or TFE-
6.16 Glass Wool, borosilicate.
fluorocarbon.
6.10 Evaporating Dishes, porcelain, 16 and 28-cm. 6.17 Electric Heat Lamp or Hot Plate.
D 4124
7. Reagents and Absorbent continue stirring for an additional 1 h. Normally1his
sufficient time for straight reduced asphalts but for airblown or
7.1 Alumina, F-20 chromatographic grade, calcined at
chemically modified asphalts the digestion time should be
413°C for 16 h and stored in an evacuated desiccator or airtight
extended to 1.5 h. After digestion, remove the flask and stirring
bottles.
assembly from the steam bath. Rinse the stirring assembly as it
7.2 n-Heptane (Note 1), 99 minimum mol % (pure grade).
is removed from the flask with n-heptane from a squeeze
NOTE 1—n-Heptane should be totally free of moisture. Pretreatment of
bottle. Cover the flask with a foil-covered rubber stopper and
n-heptane with 5A molecular sieves or by refluxing over calcium hydride
set aside overnight at ambient temperature so the precipitated
may be necessary to remove residual moisture in the solvent.
asphaltenes can settle to the bottom of the flask.
7.3 Methanol, anhydrous, reagent grade.
10.1.3 Set up a 12.5-cm diameter Büchner funnel appropri-
7.4 Toluene, reagent grade.
ately fitted with a slow to medium filter speed, qualitative-
7.5 Trichloroethylene, boiling point 86.5 to 87.5°C.
grade filter paper and a 2-L suction flask. The 1-L separatory
funnel should be suspended about 25 mm above the center of
8. Safety Precautions
the filter paper.
8.1 Most organic solvents used in these methods are flam-
10.1.4 Decant as much of the clear heptane-petrolene solu-
mable and to some degree toxic. Reference should be made to
tion as possible from the mixture prepared in 10.1.2 and place
Material Safety Data Sheets available from the supplier. These
it directly in the separatory funnel.
solvents should be handled with care and only in well-
10.1.5 Wet the filter paper in the Büchner funnel with
ventilated areas. All working areas should be kept free of
n-heptane from a squeeze bottle and apply sufficient suction to
sparks, flames, or other sources of high temperature.
the flask to secure the filter paper firmly to the funnel surface
9. Sampling and Sample Preparation
before beginning the filtration step. Add petrolene solution
from the separatory funnel at a closely controlled rate and in
9.1 Bulk samples taken in accordance with Practice D 140
such a manner that all of the filtering takes place in the center
shall be representative and free of foreign substances. Samples
for testing in 10.1.1 can be transferred by chilling to facilitate of the paper. The filter paper should be wetted periodically
from the squeeze bottle to ensure a tight seal with the funnel
fracturing the sample or by heating the sample until it has
become sufficiently fluid to pour. Caution: In no case shall the surface. After the filtering is completed, it is advisable to empty
or replace the suction flask before proceeding with the final
samples be heated more than 110°C above the expected
softening point. Transfer of a representative portion from the phase of filtration process.
bulk sample to a smaller container may be necessary for
10.1.6 Test the filtrate from 10.1.5 for insolubles by placing
determination of sample mass to the nearest 0.01 g in 10.1.1.
a drop of the filtrate on a filter paper. Refilter if a ring appears.
10.1.7 Transfer the contents remaining in the Erlenmeyer
10. Procedure
flask directly to the Büchner funnel, using additional solvent
10.1 Separation of Asphaltenes and Petrolenes:
from the squeeze bottle and repeatedly wash the asphaltene
10.1.1 Weigh to the nearest 0.01 g and place into a 2-L
cake until the filtrate becomes colorless. Take care to ensure
Erlenmeyer flask a sufficient quantity of asphalt (Note 2) so
that no insolubles creep over the edges of the filter paper into
that it yields about 10 g of petrolenes as indicated by the
the filtrate. Next, transfer the filter paper and its contents to a
following equation:
500-mL beaker and add 150 mL of n-heptane. Heat the
Sample mass, g 5 1000/1002% asphaltenes (1)
contents in the beaker for about 30 min with occasional stirring
to remove n-heptane-soluble materials entrained in the asphalt-
For paving asphalts, this would be 11 to 13 g of asphalt and
ene cake. Filter the hot solution through the same Büchner
slightly more for airblown asphalts. Unless the asphalt is in
funnel fitted with a tared, fresh piece of filter paper, using the
granular form, warm the flask gently with a heat lamp or hot
prescribed procedures. Continue washing the asphaltene cake
plate and disperse the asphalt over the bottom and lower sides
until the filtrate is colorless. Test the filtrate for insolubles as in
of the flask before adding the n-heptane solvent in the ratio of
10.1.6 and repeat this task if a ring appears.
100 mL of solvent per1gof sample.
10.2 Solvent Evaporation:
NOTE 2—The quantity of asphalt required for 10 g of petrolenes can
10.2.1 Transfer the asphaltene cake on the filter papers
easily be predetermined in accordance with Test Method D 3279.
(10.1.5 and 10.1.7) to a 16-cm evaporating dish and dry in a
10.1.2 Install an air-powered stirrer assembly into the flask
104°C oven until a constant mass is achieved. Record the net
prior to placing flask and its contents on a steam bath. The
mass of asphaltenes recovered and store if desired in a
stirring rod should rotate inside a foil-covered rubber stopper
screw-cap bottle.
that is used to seal the Erlenmeyer flask to reduce the
10.2.2 Heptane can be removed from filtrates containing
evaporation of n-heptane. Maintain the solvent temperature
petrolenes (10.1.5 and 10.1.7) using standard laboratory pro-
near its boiling point and stir the contents of the flask at a
cedures. Concentrate the petrolene solution to about 50 mL and
moderate rate until there is no visual evidence of undispersed
then transfer the concentrate to a 150-mL beaker. Sufficient
asphalt adhering to the sides of the flask. Begin timing and
fluidity should remain in the petrolene concentrate to permit
easy transfer of concentrate to a chromatographic column for
Available from Aluminum Company of America, Pittsburgh, PA. subsequent separation into the three defined fractions.
D 4124
TABLE 2 Repeat Composition Analysis (Asphalt Cement, 89
10.3 Separation of Petrolene Concentrate into Three De-
Penetration)
fined Fractions:
Mass on Sample
10.3.1 Set up the chromatographic column with appurte-
Fraction
Run 1 Run 2
nances as shown in Fig. 1. Place a concave filter pad, cut from
the bottom of an extraction thimble (6.13), on the bottom of the Saturates 10.8 11.1
Naphthene aromatics 39.3 39.9
column, and follow by 25 mm of a glasswool plug. Add 450 g
Polar aromatics 36.6 35.5
of calcined alumina while gently tapping the column with a
Asphaltenes 13.0 12.8
Total 99.7 99.3
rubber-coated object. Place a glass wool plug on top of the
alumina bed, add 50 mL of n-heptane to prewet the column,
and proceed immediately to 10.3.2.
TABLE 3 Acceptability Criteria of Test Results
10.3.2 Transfer the petrolene concentrate from 10.2.2 to the
Weight % of Sample
column, using minimum amount of n-heptane. Start addition of
Acceptable
eluants with 200 mL of n-heptane (see Table 1) from the
Standard
Range of Two
Deviation
equal-pressure funnel at a drip rate of about 5 mL/min (Fig. 1);
Results
simultaneously collect eluate at the rate of 5 6 1 mL/min in the
Single Operator Precision:
receiving funnel; and subsequently drain the eluate into tared
Asphaltenes 9 to 29 % 0.32 0.9
Saturates 8 to 16 % 0.44 1.2
containers (weighed to 0.01 g) in accordance with the schedule
Naphthene Aromatics 27 to 41 % 1.03 2.9
in Table 1.
Polar Aromatics 20 to 41 % 0.78 2.2
10.3.2.1 Caution: At no time should the liquid level in the Multilaboratory Precision:
Asphaltenes 9 to 29 % 0.95 2.7
column be allowed to drop below the top of the alumina bed
Saturates 8 to 16 % 0.70 1.9
until the final hold-up is removed.
Naphthene Aromatics 21 to 41 % 2.26 6.4
Polar Aromatics 20 to 41 % 2.37 6.7
10.3.3 Add the new eluant to the column before the final
eluate cut from the previous eluant is taken. Based on earlier
studies, such procedure regulates fractionation, provided eluate
cuts are taken in accordance with the schedule in Table 1. This where:
procedure requires close attention, especially during the col- A 5 mass of the fraction, and
B 5 mass of the sample.
lection of the saturates and naphthene aromatics fractions. The
11.2 Report percentages to the nearest 0.1 % mass.
cut point between the naphthene aromatics and polar aromatics
fractions is more obvious and may be improved by either
12. Precision and Bias
cutting short or increasing the volume of this cut as observed
by the descent of the black polar aromatic ring. The elution 12.1 Criteria for judging the acceptability of test results
obtained by this test method are provided in Table 3. Data were
volume will vary with the composition of the feed, and the cut
point should be made as the black ring reaches the bottom of obtained from tests by seven rather than ten laboratories as
recommended in Practice C 802.
the alumina bed. The naphthene aromatics fraction produces a
yellow to deep red color eluate whereas the polar aromatics 12.2 Material and range covered are described in Table 3.
These
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