Summary of Rubber Modified Asphalt Product Specifications around ...

under snow plow activity and freeze thaw climate scenarios. It is quiet, but may be more
susceptible to damage in colder climates. The information in this section could help Ontario if
open-graded rubber modified asphalt is to be considered in Ontario.
5.2.1 Mix Design Aspects
Table 6 shows the mix design method used by various agencies. Open-graded mixes could hold
more asphalt cement than gap- or dense- graded mixes, particularly if they are like the high
binder types used in Arizona and California for durability, and not for drainage.
Table 6. Mix Design from Various Agencies for Open-Graded Rubber Modified Asphalt
Agency Mix Design
Method
California Hveem mix
design
Arizona Marshall mix
design
Binder
Content and
binder type
Optimal
Binder
Content
(OBC) =
OBC1 x 1.20
Texas Superpave Binder content
based on Tex-
236-F
5.2.2 Construction Considerations
Gradation, air
voids, and others
Open-graded 12.5
mm.
Open-graded;
Absorbed asphalt
rubber, 0-1%. Use
type B smaller CR
gradation.
Notes
Mineral
admixture,
Portland cement
or hydrated lime,
1% is required.
Drain-down max
0.20%
The open-graded RMA requires higher ambient or underlying pavement temperature. There are
temperature requirements for mix production, spreading, and compaction. Different agencies
have different ways to prevent material pick up by traffic. Table 7 shows these requirements.
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