UFC 3-250-03
15 May 2001
(4) Storage. Temporary (less than 1 hour) storage of SMA in surge bins will be used only for
balanced production capacity. Storage in heated and insulated storage bins should be limited to 4 hours
unless laboratory testing indicates additional time is acceptable. Acceptability must be based on no
adverse changes in binder properties and excessive draindown not occurring. No mixture shall be
stored overnight.
e. TEST SECTION. The construction of a test section is important to allow examination of the
contractor's mixing and placement procedures. This is especially true if the contractor has not had
experience in mixing or placing SMA.
f. PLACEMENT.
(1) Equipment. The trucks, pavers, distributors, and other general equipment are the same as
those used for any asphalt concrete construction. Only steel-wheel rollers are used for SMA. Rubber-
tire rollers are not used for SMA. Vibratory rollers can be used but care must be taken to prevent
breakdown (fracture) of the aggregate.
(2) Surface preparation. The surface shall be cleaned of all loose or deleterious material. A
tack coat shall be applied as described in paragraph TACK COAT in chapter SPRAY APPLICATIONS.
The atmospheric temperature shall be a minimum of 7EC (45EF) and rising at the time of placement.
(3) Paving. The SMA mixture, when delivered to the paver, shall be a minimum temperature
equal to the laboratory compaction temperature as determined in ASTM D 1559.
(4) Compaction. The SMA shall be compacted to a minimum of 94 percent of maximum
theoretical density. Rolling shall be accomplished with steel-wheel rollers. Vibratory rollers can be used
provided the aggregate is not crushed. Rubber-tire rollers will not perform well with SMA due to the high
amounts of asphalt cement in the mixture causing asphalt build up on the wheels. Rolling should
continue until the required density is obtained. This is usually controlled through the use of a nuclear
density gage. Due to the large amount of binder coating the aggregate particles it is important that the
roller drums be properly moistened with water containing small amounts of detergent to prevent
adhesion. Traffic should remain off the SMA surface until it has cooled below a minimum of 60EC
(140EF). Flooding with water from a truck after the completion of all rolling has been used to increase
the rate of cooling to allow for earlier trafficking.
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