WORKING MANUAL
FOR
BITUMEN EXTRACTOR
ELECTRICALLY OPERATED
The equipment comprises of the followings:
1. Centrifuge Extractor, Electrically operated
2. Tommy Pin
3. Filter Paper Discs
4. Dimmerstat
INTRODUCTION: The Bitumen extractor is used for the
quantitative determination of bitumen in hot mixed paving mixtures and pavement
samples. The bitumen content is
calculated by different from the weight of the extracted aggregate, moisture
content and ash from an aliquot part of the extract. It meets the requirements of ASTM D 2172,
AASHO T-58, T-164.The apparatus is
suitable for operation on 230 volts, 50 Hz , single phase , AC supply.
DESCRIPTION: ‘HT’ Centrifuge Extractor consists of a bowl
housing. The bowl is provided with a
cover plate ad it is secured in position by tightening a nut.The bowl housing
is provided with an outlet. The housing
is mounted on a body enclosing the
motor.
SPECIMENT
PREPARATION: If the mixture is not
sufficiently soft to separate with a spatula or trowel, place it in a large,
flat pan and warm to 240OF (116OC). Only until it can be
handled. Separate the particles of the
mixture as uniformly as possible using care not to fracture the mineral
particles. Normally 1000g samples are used
for extraction. For routine testing smaller
samples may be used when the maximum size aggregate therein is less than
6mm. The precision of the method becomes
less as the aggregate size increases due to variation in sample. This procedure may be used on mixtures
containing aggregate larger than 25mm by using samples weighing at least
3000g. They may be tested by extracting
1000g at a time. They may be tested by extracting 1000g at a time.
TEST
PROCEDURE:
Determine the moisture content of the sample using a standard procedure. Weigh a 1000g sample in the bowl. Cover the sample in the bowl with benzene or
trichloriethylene and allow sufficient time for the solvent to disintegrate the
sample ( Not over one hour).
Place the bowl containing the sample and the solvent
inside the housing . Dry and weigh
filter disc and fit it around the edge of bowl.
Clamp the cover plate tightly on the bowl. If necessary the tommy pin may be used for
loosening the nut for removing the cover plate.
Position the housing cover and clamp it to the housing. Place the beaker under the outlet.
Start the centrifuge, revolving slowly and gradually
increase the speed until the solvent ceases to flow from the outlet. Allow the centrifuge to stop add 200ml of
trichloroethylene or benzene and repeat the procedure. Repeat
the procedure not less than three times so that the extract is clear and
not darker than light straw colour.
Collect the extract and washings in a suitable graduated vessel.
Remove the filter paper disc from the bowl and dry
in air. Removes as much of the mineral
matter adhering to the disc as possible and add to the aggregate in the
bowl. Dry the disc to constant weight in
an oven at 230 + 9OF (110 + 5OC). Dry the contents of the bowl on a steam bath
and then to constant weight in an oven at 230+ 9OF (110 + 5OC).
Record the volume of the total extract in the
graduated vessel. Agitate the extract
thoroughly and immediately approximately 100ml into a previously weighed
ignition disc. Evaporate to dryness on a
steam bath. Ash the residue at a dull red
heat (500 to 600oC). Cool and add 5mlk of saturated ammonium
carbonate (NH4)2CO3 solution per gram of ash.
Digest at room temperature for one hour. Dry in
an oven at 100oC to constasnt weight, cool lin a desicastor
and weigh.
Calculate the weight of ash in the total volume of
extract.
V1
Total
ash W4 = G
V1 - V2
Where
G = ash
in aliquot in grams.
V1 = total
volume in milliliters.
V2 = volume
after removing a aliquot in milliliters
Calculate the percentage of bitumen in the samples
as follows
(W1-W2)
– (W3-W4)
Bitumen content of dry sample, percent = x 100
W1-W2
Where
W1 = weight
of sample
W2 = weight
of water in sample
W3 = weight
of extracted mineral matter.
W4 = weight
of ash in extract.
Add the increase in weight of filter disc to the
weight of the recovered aggregate and the ash in the recovered bitumen.
MAINTENANCE:
KEEP ALL THE PARTS CLEAN.
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