UFC 3-250-03
15 May 2001
(f) The type and amount by weight of mix of stabilizer additive to be used.
(g) Additional information required as part of the JMF shall include the following:
[1] The material sources for all ingredients.
[2] The material properties, as listed, for all ingredients:
[a] The specific gravities of the individual aggregates and asphalt.
[b] The L.A. Abrasion of the aggregates.
[c] The sand equivalent value of the combined aggregate.
[d] The flat and elongated percent of the coarse aggregate (3 to 1 and 5 to
1 ratios), retained above the 4.75 mm (No. 4) sieve.
[e] The plastic index of the aggregate.
[f] The absorption of the aggregates.
[g] The asphalt temperature/viscosity curves.
[3] The mixing temperature.
[4] The mix design test property values and curves used to develop the job mix in
accordance with those provided for hot-mix asphalt in this chapter and also in the Asphalt Institute's
Manual Series No. 2 (MS-2).
[5] The plot of the gradation on the FHWA 0.45 power gradation chart.
d. MIXING PLANTS. SMA has been mixed in both batch and drum mix plants. These plants can
be utilized with none or minor adaptations required to mix the SMA components.
(1) Batch plants. The mineral filler will be added directly into the weigh hopper. Most batch
plants have an existing mechanism for accomplishing this. However, special attention is required to
assure accurate proportioning of the relatively large amounts of filler required for SMA. The fiber is also
added directly into the weigh hopper and should occur when the hot aggregate is also being placed into
the hopper. An alternative method of adding the fibers directly to the pugmill as the hot aggregates are
added has also been used successfully.
(2) Drum-mix plants. The mineral filler will be added directly into the drum mixer. Special
attention is required to assure accurate proportioning of the relatively large amounts of filler added. The
fiber is also added directly into the drum mixer. A separate feeding system is usually employed
especially in the case of loose fibers. These fibers are added to the aggregates far enough down the
drum to avoid direct contact with the burner flame.
(3) Mixing time. The time required to mix SMA is usually greater than dense-graded hot-mix
asphalt. For batch plants the dry-mixing time will be increased from 5 to 15 seconds and wet-mixing will
be increased at least 5 seconds for cellulose fibers and up to 5 seconds for mineral fibers.
2-39
Previous Page
