UFC 3-250-03
15 May 2001
4.
DENSE-GRADED HOT-MIX ASPHALT.
a. General. Dense graded hot-mix asphalt concrete consists of a mixture of well graded aggregate
and asphalt cement. There are several other possible non-asphalt binders including tar and rubberized
tar. However, asphalt cement is the binder used in a wide majority of paving mixtures. The hot-mix
asphalt is produced at a central plant, laid to the desired grade with an asphalt spreader, and
compacted. Hot-mix asphalt provides a high-strength, water resistant, smooth riding surface.
b. Laboratory testing for mix design.
(1) Contractor provided job-mix-formula. Current practice is for the contractor to do the mixture
design and develop the job-mix-formula (JMF) for the aggregates and asphalt used in the paving project.
The contractor should supply a sufficient amount of aggregate and asphalt to the contract officer or his
representative for possible verification tests. If verification tests are not performed, these material
samples should be kept until the project is completed and accepted. The JMF supplied by the contractor
should contain, as a minimum, the following information:
(a) Percent passing each sieve size of individual aggregate and combined gradations.
(b) Percent of optimal asphalt cement
(c) Percent of each aggregate and mineral filler to be used.
(d) Asphalt viscosity grade, penetration grade, or performance grade.
(e) Number of blows of hammer per side of molded specimen.
(f) Laboratory mixing temperature.
(g) Lab compaction temperature.
(h) Temperature-viscosity relationship of the asphalt cement.
(i) Plot of the combined gradation on the 0.45 power gradation chart, stating the nominal
maximum size.
(j) Graphical plots of stability, flow, air voids, voids in the mineral aggregate, and unit
weight versus asphalt content. (example MS-2).
(k) Specific gravity and absorption of each aggregate.
(l) Percent natural sand.
(m) Percent fractured faces (in coarse aggregate).
(n) Fine aggregate angularity.
(o) Percent flat or elongated particles (in coarse aggregate).
(p) Tensile strength ratio (TSR).
(q) Antistrip agent (if required) and amount.
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