Table of Contents

2.8.1 Nominal Mix Size

The nominal size of an asphalt mix is an indication of the maximum particle size present and is usually expressed as a convenient whole number above the largest sieve size to retain more than 0% and less than 10% of the aggregate material (AS 2150).

The selected nominal size of the mix will be determined by:

  • location of asphalt course in the pavement
  • proposed compacted thickness of the layer
  • functional requirements of the asphalt layer.

Table 2.1 indicates typical nominal mix sizes for different applications.

Table 2.1: Typical mix sizes for various applications

ApplicationTypical mix size

Dense graded wearing course:

  • lightly trafficked pavements
  • medium to heavily trafficked pavements
  • highway pavements
  • heavy duty industrial pavements

7 or 10 mm

10 or 14 mm

Generally 14 mm (also 10 mm)

14 or 20 mm

Dense graded intermediate courseIn general it is better to use the largest size practicable where the wearing course is dense graded asphalt. Where the asphalt surface is open graded asphalt, the largest size mix used in this application is typically 14 mm
Dense graded basecourseNormally 20 mm. 28 mm may also be used depending on layer thickness and availability. 40 mm has been used in the past but now largely discontinued through difficulties associated with increased segregation in larger sized mixes and general unavailability
Dense graded corrective course5, 7, 10, 14 or 20 mm
Stone mastic asphalt wearing course7, 10 or 14 mm
Open graded wearing course10 or 14 mm
Open graded basecourse (drainage layers)14, 20 or 28 mm
Fine gap graded asphaltGenerally 10 mm (also 7 mm)

Minor patching

Major patching

10 mm (also 5, 7, 14 and 20 mm)

All sizes as appropriate