COATING &STRIPPING OF
This IM is intended to provide
the procedure for determining the ability of cutback or emulsified asphalt to
retain a film on aggregate in the presence of water.
Container for mixing having rounded corners, such as an 8 or 16
oz. (240 or 480 ml) seamless ointment tin
Balance with a capacity of at least 200 grams and accurate to 0.1
Spatula with a stiff blade approximately 1 in. in width and 4 in.
Oven capable of maintaining any temperature between 140°F and
275°F ± 2°F (60°C and 135°C ± 1°C)
Two sieves, one having 3/8 in. (9.5 mm) size mesh and the other
No. 4 (4.75 mm) size mesh.
Glass beaker with 20 oz. (600 ml) capacity
- Standard aggregate-Sioux Falls
quartzite, which passes the 3/8 in. (9.5 mm) sieve and is retained on the
No. 4 (4.75 mm) sieve. The aggregate is washed to remove fines, dried at
275°F to 300°F (135°C to 149°C) to a constant weight, and stored in
airtight containers until required for use.
- Project aggregate-aggregate to
be used with emulsion for the project for test purposes. The aggregate is
graded and prepared in the same manner as standard aggregate in A1.
- Distilled water
Aggregate Coated with Cutback Asphalt
- Weigh 100 grams of standard
aggregate into the mixing container.
- Add 5.5 ± 0.2 grams of cutback
asphalt; preheat when necessary to the temperature specified in Table 1.
- Mix the cutback and aggregate
vigorously with the spatula for 2 minutes. MC-800 and MC-3000 grades may
be warmed over a hot plate during the mixing period just sufficiently to
permit effective mixing, but not above the temperature limits in Table 1.
the coated aggregate in its original container for 2 hours at 140°F
(60°C).5.After curing, remix with the spatula while the mixture cools to room
temperature or until the asphaltic residue ceases to drain off the aggregate.
Coating of the aggregate must be complete. No bare spots are permissible.
- Transfer the coated aggregate
to the 20-oz. glass beaker. Cover immediately with about 16 oz. of
distilled water at room temperature. Allow the coated aggregate to remain
immersed in the water for 16 to 18 hours at room temperature.
- Without disturbing or agitating
the coated aggregate, remove any film floating on the water surface.
Illuminate the specimen by a flashlight or shaded lamp, positioned to
eliminate glare from the surface of the water. By observation through the
water from above, visually determine if the percent of retained film on
the aggregate surface is above or below 95%. Any thin brownish,
translucent areas are considered fully coated.
Aggregate Coated With Emulsified Asphalt
This procedure is identical to
the method of coating standard aggregate with cutback asphalt with the
- Select a sample of aggregate,
which is intended for the project, and prepare it in the same manner as
described in B1.
- Weigh 100 grams of the project
aggregate, which has been properly prepared, into the mixing container.
Add 8.0 ± 2.0 grams of emulsified asphalt, both at room temperature and
- Place the mixing container,
with aggregate and emulsion, in an oven maintained at 275°F (135°C) for 5
- Remove from the oven and stir
with the spatula until the aggregate is thoroughly coated.
- Oven-cure the coated aggregate
for 2 hours at a temperature of 275°F (135°C).
- Complete the test by following
B5 through B7.
1. Report the
remaining coated area as “Above 95%” or “Below 95%.”
Temperature for Mixing
MC-30 and MC-70
95°F ± 5°F (35°C ± 2.5°C)
125°F ± 5°F (52°C ± 2.5°C)
155°F ± 5°F (68°C ± 2.5°C)