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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