UFC 3-250-03
15 May 2001
CHAPTER 6
MISCELLANEOUS MIXTURES
1. SAND-ASPHALT MIXTURES. In regions such as coastal areas where sand of good quality is the
only local aggregate available, the sand can be used to produce an economical base or surface course.
Sand mixtures meeting these minimum requirements may be considered for paving roads and streets
where light loads are anticipated and where considerable savings may be realized by using locally
available sand. Mineral filler is often added to increase the density and stability of the mixture, but
mineral filler is sometimes omitted in designing sand-asphalt mixtures for asphalt-stabilized base
courses. Asphalt cement, cutback asphalt, or emulsified asphalt may be used for binder. Cold-laid
asphalt mixtures may be mixed at a central plant, mixed with a travel plant, or mixed in place. Hot-mix
asphalt is mixed at a central plant. Sand mixes are fine textured, dense, and relatively impermeable.
The stability and durability of the sand mixes depend on the quality and grading of the fine aggregate,
the amount and grade of asphalt binder, and the degree of control exercised in construction operations.
The sand should be sufficiently well-graded to meet the specified aggregate requirements for the type of
course to be constructed and should be free from excessive amounts of foreign matter. In many cases,
a. Advantages and disadvantages. Sand-asphalt mixes can be produced with locally available
materials at a relatively low cost. The use of sand mixes is limited due to the relative lack of strength
and durability.
b. Uses. Sand mixes will not be used as surface or intermediate courses for airfield and heliport
pavements designed for high-pressure tires or for pavements designed for solid-rubber tires, steel
wheels, or tracked vehicles. High pressure truck tires and ATV tires should not be allowed on sand
asphalt mixes. Sand mixes may be considered for asphalt-stabilized base courses for all types of traffic
areas and for any course in nontraffic areas. Sand mixes may be considered for surface and
intermediate courses with pavements subjected to low-pressure tires (690 kPa, 100 psi or less) and low
traffic volumes. In this case, trial mixes should be made and tested in the laboratory. This type of mix
has been used to provide temporary travel paths for construction vehicles over completed asphalt
concrete pavements. The maximum sized aggregate particle should be no more than 9.5 millimeters
(3/8 inch) to prevent the traffic from making indentations on the underlying asphalt concrete pavement.
2. SHEET ASPHALT. Sheet asphalt is a refined type of hot sand-asphalt pavement in which the
grading, quality of sand, amount of mineral filler, and asphalt cement content are carefully controlled.
The percentage of asphalt required is generally higher than that used for sand asphalt. Sheet asphalt
provides a smooth, impermeable, homogeneous surface course that gives best service when traffic is
spread evenly over the pavement. Normally, sheet asphalt is used for surface courses only and is
constructed 38 to 50 millimeters (1-1/2 to 2 inches) thick over an intermediate course.
3. STONE-FILLED SHEET ASPHALT. Stone-filled sheet asphalt normally consists of up to 35
percent coarse aggregate, well-graded sand, mineral filler, and asphalt cement prepared in the same
manner as sheet asphalt. The coarse aggregate should pass the 16 millimeter (5/8-inch) sieve. The
stone-filled sheet asphalt mixture is a type of sheet asphalt mixture and has the same general
characteristics. The percentage of coarse aggregate will vary proportionally when the specific gravities
of the fine aggregate and coarse aggregate portions are not uniform. Stone-filled sheet asphalt
pavement is used generally as a surface course constructed 38 to 50 millimeters (1-1/2 to 2 inches) thick
and is sometimes called "Topeka Mix." The uses of this mixture should be limited to those given for
SAND-ASPHALT MIXTURES.
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