Geoscience Reference
In-Depth Information
13.17 CBR values for pavements
The applicable CBR values depend on both the pavement layer and closeness to
the applied load.
Table 13.17 CBR values for pavements.
Pavement layer
Design traffic (ESA repetitions)
Minimum CBR %
Base
>
10 6
80
<
10 6
60
Upper Sub base
>
10 6
45
<
10 6
35
Lower Sub base
>
10 6
35
10 6
25
<
Capping
N/A
10
13.18 CBR swell in pavements
The CBR swell should also be used to assess pavement quality.
Table 13.18 Soaked CBR swell in pavement materials.
Pavement layer
Pavement type
Soaked CBR swell (%)
Base
Rigid, Flexible, CTB
0.5
<
Sub base
Rigid, CTSB
1.0
<
Flexible
<
1.5
Capping
Rigid overlying
1.5
<
CTB overlying with granular sub base
<
2.0
CTSB overlying
1.5
<
Flexible overlying
2.5
<
For low rainfall areas (
<
500mm), soaked CBR
<
1.5% may be acceptable for the
base layer.
13.19 Plasticity index properties of pavement materials
Plasticity index of the pavement influences its performance.
Table 13.19 Plasticity index for non standard materials (adapted from Vic Roads 1998).
Pavement type
Pavement layer
Rainfall
500 mm
500 mm
<
>
Unsealed
Base/shoulder
PI
15%
PI
10%
<
<
Sub base
PI
<
18%
PI
<
12%
Sealed
Base/shoulder
PI
10%
PI
6%
<
<
Sub base
PI
12%
PI
10%
<
<
 
 
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