Subgrades and pavements - Geotechnical Investigation and Design Tables - page 164

Table 13.21 Typical elastic parameters of pavement layers (Austroads, 2004 and 1992).

Pavement layer Typical Typical

modulus (MPa) Poisson's

ratio

Asphalt at temperature 10 ◦ C 11,500 0.4

25 ◦ C 3,500 0.4

40 ◦ C 620 0.4

Unbound granular High quality crushed rock Over 500/350 0.35

(Modified/standard Base quality gravel granular 400/300 0.35

compaction) below thin Sub base gravel material 300/250 0.35

bituminous surfacings
Cemented material Crushed Rock, 2 to 3% cement (lean mix) 7,000 0.2

(Standard compaction) Base quality natural gravel 4 to 5% cement 5,000 0.2

Sub base quality natural gravel 4-5% cement 2,000 0.2

13.22 Typical values of existing pavement modulus
•

The moduli for existing asphalt and cemented materials is reduced due to cracking.

•

Apply cracked value when used with clay subgrades with WPI > 2200.

Table 13.22 Typical elastic parameters of pavement layers (Austroads, 2004).

Existing pavement layer Cracked modulus (MPa)

Asphalt at temperature 15 ◦ C 1,050

25 ◦ C 880

40 ◦ C 620

Cemented material Post fatigue phase 500

13.23 Equivalent modulus of sub bases for normal base
material

•

The equivalent modulus combines the effect of different layer. Aminimum support
requirement is required.

Table 13.23 Selecting of maximum modulus of sub - base materials (Austroads, 2004).

Thickness of Suggested vertical modulus (MPa) of top sub-layer of normal base material

overlying
material Modulus of cover 1000 2000 3000 4000 5000

material (MPa)

40 mm 350 350 350 350 350

75 mm 350 350 340 320 310

100 mm 350 310 290 270 250

125 mm 320 270 240 220 200

150 mm 280 230 190 160 150

175 mm 250 190 150 150 150

200 mm 220 150 150 150 150

225 mm 180 150 150 150 150

≥

250 mm 150 150 150 150 150