UFC 3-250-03
15 May 2001
(3) Cement. The portland cement used should conform to ASTM C 150. The portland cement
used can be either type I, II, III, or IV. Type I is the cement most widely used for RMP applications. The
other types can be used where moderate to high sulfate- resistance or high early-strength are required.
(4) Cross polymer resin additive. The cross polymer resin additive used is Prosalvia L7 (PL7)
and it is a proprietary product. PL7 is generally composed of five parts water, two parts cross polymer
resin of styrene and butadiene, and one part water reducing agent. The PL7 is used as a plasticizing
and strengthening agent.
3. MIXTURE DESIGN.
a. Open graded asphalt mixture. The optimum asphalt content for the open-graded asphalt mixture
is determined through a modified Marshall mix design procedure. Marshall laboratory samples
152.4 millimeters (6 inches) in diameter by 63.5 millimeters (2-1/2-inches) in height are produced using
the determined JMF aggregate gradation and a series of asphalt contents ranging below and above an
estimated optimum asphalt content value. The estimated optimum asphalt content is determined using
a procedure developed in France and based on aggregate properties. The procedure is outlined below:
5
Optimum asphalt content ' 3.25()
where
2.65
=
where G = apparent specific gravity of the combined aggregates
G
G = conventional specific surface area
= 0.21G + 5.4S + 7.2s + 135f
G = percentage of material retained on the 4.75 millimeter (No. 4) sieve
S = percentage of material passing the 4.75 millimeter (No. 4) sieve and retained on the
600 Fm (No. 30) sieve
s = percentage of material passing the 600 Fm (No. 30) sieve and retained on the 75 Fm
(No. 200) sieve
f = percentage of material passing 75 Fm (No. 200) sieve
If, for example, the estimated optimum asphalt content calculated for a given aggregate gradation was
4.2 percent, then the asphalt contents used for the subsequent laboratory Marshall sample evaluation
could be 3.8, 4.0, 4.2, 4.4, and 4.6 percent. The 152.4 millimeter (6-inch) diameter Marshall samples are
compacted in the laboratory using a 4.536 kilogram (10-pound) hand hammer with a 152.4 millimeter
(6-inch) diameter impact plate. The samples are compacted at 121EC (250EF) using 25 blows on one
side of the sample. Three samples are produced for each of the five asphalt contents used, and the
resulting average voids data of percentage of voids total mix and voids filled are used to finalize the
selection of an optimum asphalt content. As a general rule, as the percent of asphalt increases, the
voids total mix will fluctuate over a relatively small range. Also, the voids filled will increase slowly until
the percentage starts to show a significant increase indicating that further increases in asphalt content
are working more to fill the void spaces rather than coating the aggregate particles. This is an
undesirable condition since an excess amount of asphalt cement in the RMP void structure will hinder
the slurry grout penetration upon application. The asphalt content selected should be below the point
where voids filled shows a significant increase and where the voids total mix are within the 25 to
8-3
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