D 2041 Supplemental Procedure for Mixtures

Containing Porous Aggregate Not Coin-pletely Coated

9.1 If the pores of the aggregates are flot thoroughly sealed by a bituminous film, they may become saturated with water during the evacuation procedure. To determine if this has occurred, proceed as follows after com-pleting the procedure in accordance with 7.4.1, 7.4.2, or 7.4.3. Drain water from the sample. To prevent loss of fine particles, decant water through a towel held over the top of the container. Break several large pieces of aggregate and examine broken sur-faces for wetness.

9.2 If the aggregate has absorbed water, spread the sample before an electÉic fan ta remove surface moisture. Weigh at 15-min intervals, and when the loss in mass is less than 0.05 % for this interval, the sample may be considered to be surface dry. This proce-dure requires about 2 h and shah l be accom-panied by intermittent stirring of the sample.

Break conglomerations of mixture by hand.

Take care to prevent loss of particles of mixture.

9.3 Ta calculate the specific gravity of the sample, substitute the final surface-dry mass for A in the denominator of Eqs 1, 2, or 3.

Report

10.1 The report shall include the follow-ing:

10.1.1 Specific gravity of the mixture to the third decimal place as: sp gr 25/25°C.

10.1.2 Type of mixture.

10.1.3 Size of sample.

10.1.4 Number of samples.

10.1.5 Type of container.

10.1.6 Type of procedure.

Precision

11.1 Criteria for judging the acceptability of specific gravity test results obtained by this method are given in the following table:

Acceptable Standard Range of Deviation Two Re- Test and Type Index (1S) sults (D2S) Test results obtained without

use of Section 9A

Single-operator precision 0.0040 0.011 Multilaboratory precision 0.0064 0.019

Acceptable Standard Range of Deviation Two Re- Test and Type Index (1S) sults (D2S) Test results obtained with use

of Section 9 applicable for bowl determination only 8

Single-operator precision 0.0064 0.018 Multilaboratory precision 0.0193 0.055

I Basis of estimate: 3 replicates, 5 materials, 5 labora-tories.

8 Basis of estimate: 2 replicates, 7 materials, 20 labora-tories.

11.2 The figures given in Column 2 are the standard deviations that have been found to be appropriate for the conditions of test de-scribed in Column 1. The figures given in Column 3 are the limits that should flot be exceeded by the difference between the re-sults of two properly conducted tests. Muid-laboratory precision has flot been verified for the 4000-ml pycnometer (Type C) or for the large-size plastic pycnometer (Type D).

Rapid Test Version for Relative Specific Gravity

12.1 Since the large-size plastic pycnome-ter may be safely used in a plant laboratory and since a relative specific gravity may be a convenient means of monitoring the uniform-ity of production of bituminous mixtures, a rapid test version of Method D 2041 is of-fered. This version permits lower vacuum (water aspirator or vacuum pump) and shorter evacuation time. Such measurements cannot represent the zero air voids condition and, therefore, are not suitable for determination of air voids in field or laboratory-compacted pavement samples. On the other hand, if a vacuum of 30 mm Hg (4 kPa) is attained for the 5 ta 15 min specified, the results are valid theoretical maximum specific gravities since the hot dispersion technique given in 12.2 is equivalent to letting the sample cool and breaking conglomerates by hand as in 7.1 and

12.2 Procedure for Rapid Test Version:

12.2.1 The mi, cnometer is previously cali-brated as outlinecl in Section 5.

12.2.2 Tare the hot sample (approximately 6000 g) directly from the truck into water in the pycnometer. latch dame in place. and disperse sample by shaking vigarously using a back-and-forth rolling motion with the pyc-

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nometer tipped up about 3() deg and with the skirt still in contact with the bench. Measure;- ment of sample mass by weighing the sample container before and after transferring the test portion to the pycnometer negates possiL ole error due to water evaporation loss.

12.2.3 Add adclitional water to bring the level about midway up into the dome and applv vacuum for about 5 min. The time required under vacuum will depend on the mix and on the test conditions (vacuum, shak-ing, etc.), but once established, should be maintained with -±0.5 min for repeat tests.

See Notes 5 and 7.

NOTE 7—The degree of vacuum specified in 7.3 may not be attainable in plant laboratories using a water aspirator, particularly when testing hot sam-ples. Consistent and repeatable results can be ob-tained, however, if the test conditions remain rea-sonably constant at some point over an absolute pressure range from 0 to 250 mm Hg (0 to 34 kPa) and final water temperature up to 70°C (160°F). If the specific gravity test results thus obtained are to be used to Monitor asphalt content, the specific gravity of the combined aggregates w be used in

the calculations must be that value established in the same plant and under the same test conditions.

12.2.4 The rest of the procedure is the same as 7.4.3. Fill with water, insert vented stopper, wipe water off the stopper (once) and dry the outside using the same technique as during calibration. Weigh and- take the temperature.

12.3 Calculation —Use Eq 3 in 8.1.3.2.

NOTE 8—This rapicl test version makes it possi-ble for a plant laboratory technician to get a reading on a specific gravity of the mix within a total elapsed time of 10 min or less, which is sufficiently accurate to reflect a significant change in the specific gravity of anv of the aggregate fractions or the bitumen or in the relative proportions of each ingredient in the mixture. The bias, if any, is small and essentially constant for a given operator in a given plant.

Limited data show the precision (repeatability) to be comparable to that reported in 11.1 for results obtained on smaller test portions using the flask and bowl containers without use of Section 9, that is, standard deviation = 0.004 or less for surface and binder mixes, 0.007 or less for base course mixes.

MASS OF FLASK IMMERSED IN WATER. 9

632

WA'TER

NET CHANGE

FROM 77°F PYCNOMETER

160 180 200 PLUS • GAIN IN MASS

GO 80 100 120 140 0

o

2 0

•

90

80

80 60 40 20 0 mASS, 9 60

70

260 240 220 200 180 160 140 120 100

FIG. 3 Effect of Change in Density of Water and Volume of Pycnometer (D) with Change in Temperature.

150

140

130

120

20 40

'

MINUS - LOSS IN MASS

I

D 2041

50

4

30

20

10

0

90

80

70

40

WEIGHT IN GRAMS

16,240 250 260 270 280 290 300 310 320 330 340 350 16,360

MASS OF PYCNOmETER FILLE() WITH wATER. 9

FIG. 2 Example Calibnation Curve for Pycnometer (D).

1

80

150

FIG. 4 Correction Curves for Thermal Expansion of Bitumen, H, in Eq. 3.

6 -3.6 -3.2 .3.0 -2.8 -2.6 .2.4 -2 2 .2.0 .1.8 -1.6 .1A .1.2 .1.0 -06 -0 6 •0.4 .0.2 0 .0.2 1 6 .-0.8 .1.0 .1.2 .1 CORRECTION, 9

D 2041

• URVE 0 OENSITY OF VVATERI CURVE R MULTIPLIER

0.982 0.984 0.986 0.988 0.990 0.992 0.994 0.996 0.998 1.000 1 002 OENSITY OF WATER. M1/M3, AND MULTIPLIER, R

FIG. 5 Carres D and R for Eq. 3.

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This standard is subject to revision at any lime by the responsible technical committee and Must he reviewed everv jie vears and if flot revised,• either reapproved or withdrawn. Your comments are invited either for revision of Mis standard or

f

19103, which will schedule a further hearing regarding yoUr comments. Failing satisfaction there. .cou mac appeal w the A STM Board of Directors.

150

140

130

120

g li

100

90

80

70

60 0.980

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Gouvernement du Québec Ministère des Transports Laboratoire Central