Standard Hawai'i HMA Mixes

HAPI Pavement Note on Mix Designation Nomenclature

Differentiating between HDOT mix designations and County mix designations can be confusing.  Prior to 1994, HDOT and the Counties used different mix designations with the State using roman numerals II, III, IV and V and the Counties using arabic numerals 2, 3, 4 and 5.  The State's 1994 Standard Specifications attempted to standardize mix terminology throughout the State so that it conformed to State (HDOT) mix designations.  However, some County specifications (especially in the City and County of Honolulu) still use the old County mix designations (2, 3, 4 and 5). Therefore, one must be extremely careful when specifying mixes to say which mix designation system is being used.  For example, a mix conforming to HDOT Mix IV specifications should be referred to as a "State mix four" for clarity because a "County mix four" is quite different. For clarity, this Guide refers to mix types by first designating whether they are a "State mix" or "County Mix" and then writing the mix number in roman numerals (if it is a State mix) or arabic numerals (if it is a County mix).

 

Standard HDOT Mixes

• State Mix II. Dense-graded HMA. The nominal maximum aggregate size is 1 inch and asphalt binder content ranges from 3.8 to 6.1 percent by total weight of mix. This is essentially a deprecated mix; it has not been used for quite some time and is rarely, if ever, specified.
• State Mix III. Dense-graded HMA primarily used in heavy-duty applications such as airfields and heavy industrial applications (like harbors), but it can also be used as a binder course. The nominal maximum aggregate size is 0.75 inches and compacted lift thicknesses should be between 2 and 3 inches. Asphalt binder content ranges from 4.3 to 6.1 percent by total weight of mix. This mix can be produced but can be expensive as there are usually few, if any, 1-inch minus aggregate stockpiles available.

• 	Figure 1: State Mix IV Over ACB

  State Mix IV. Dense-graded HMA used for surface courses. This is the standard HDOT highway surface course mix. The nominal maximum aggregate size is 0.5 inches and compacted lift thicknesses should be between 1.5 and 3 inches. Asphalt binder content ranges from 4.3 to 6.5 percent by total weight of mix. This mix is not recommended for parking lots because its surface finish can be a bit rough and it is more difficult to place and compact in the confined geometry of parking lots.
• State Mix V. Dense-graded HMA used for surface courses.   Common mix used for residential roads, collectors, parking lots, recreational facilities and paths. The nominal maximum aggregate size is 0.375 inches and compacted lift thicknesses range should be between 1.25 and 3 inches. Asphalt binder content ranges from 4.8to 7.0 percent by total weight of mix. Because of its smaller nominal maximum aggregate size, it is the best choice for thin lifts (less than 1.5 inches) and leveling courses.
• Hot Mix Asphalt Base Course (HMAB Course). Dense-graded HMA primarily used for binder courses and HMA base courses. The nominal maximum aggregate size is 1 inch and compacted lift thicknesses should be between 2.5 and 6 inches. This is the HDOT designation for what this Guide calls ACB. Asphalt binder content ranges from 3.8 to 5.7 percent by total weight of mix. It is comperable to a State Mix II or County Mix 2 in gradation with just a bit less asphalt cement.

Standard County Mixes

• County Mix 2. Dense-graded HMA. The nominal maximum aggregate size is 1 inch and asphalt binder content ranges from 4.5 to 6.5 percent by total dry weight of the mixture. Primarily used for binder courses and HMA base courses. This is quite similar to a State mix II.
• County Mix 3. Seldom-used Dense-graded HMA intended for use as a HMA base course layer. The nominal maximum aggregate size is 0.75 inches and compacted lift thicknesses should be between 2 and 4 inches. Asphalt binder content ranges from 4.5 to 7.0 percent by total dry weight of the mixture. This is quite similar to a State mix III.
• County Mix 4. Dense-graded HMA used for surface courses. This is the standard County surface course mix. The nominal maximum aggregate size is 0.375 inches and compacted and compacted lift thicknesses range should be between 0.75 and 3 inches. Asphalt binder content ranges from 5.5 to 7.5 percent by total dry weight of the mixture. This is similar to a State mix V (and not, as you might think, a State mix IV).
• County Mix 5. Dense-graded HMA used for surface courses.   Common mix used for driveways, parking lots, recreational facilities and paths.  This mix is not recommended for roads.  The nominal maximum aggregate size is less than 0.375 inches and compacted layer thicknesses range from 0.75 to 3 inches.  Asphalt binder content ranges from 6.0 to 8.0 percent by total dry weight of the mixture.  Because of its smaller nominal maximum aggregate size, it is the best choice for thin lifts (less than 1.75 inches) and leveling courses.
• Asphalt Treated Base (ATB).  Dense-graded HMA primarily used for binder courses and HMA base courses.  The nominal maximum aggregate size is 1 inch and compacted lift thicknesses should be between 2.5 and 4 inches.  Asphalt binder content ranges between 4.0 and 5.0 percent by dry weight of aggregate.  Note that this method of expressing asphalt content is consistent with HDOT's method and not the County method used for mixes 2, 3, 4 and 5. This is the County designation for what this Guide calls ACB. The County designation RATB is an ATB that includes RAP.

Superpave Mixes
Although they are currently not contained in the 2005 Standard Specifications for Road, Bridge and Public Works Construction, Superpave mixes have been and will continue to be used in Hawai'i.  Superpave mixes are appropriate for both binder courses and surface courses of arterials and highways.  Standard Superpave mix designations are 3/4 inch Superpave, 1/2 inch Superpave and 3/8 inch Superpave.