Geoscience Reference
In-Depth Information
Table 17.8
Dam core material classification to minimise internal erosion.
Consideration
Reduce erosion
Erosion resistance
Criteria
Rate of erosion
Higher compacted
Addition or inclusion
Maximum stone
decreases with
density reduces
of stone chips
size to allow
increasing
rate of erosion
improves erosion
compaction
plasticity Index
resistance
(PI)
Measure ideal
PI
15% to 20%
Dry Density (DD)
Stones
10% to 20%
Stone size
2mm
=
=
=
≥
98% (Standard
to 60 mm
proctor)
Fair
PI
≥
12%
DD
≥
95%
Stones
≥
5%
Stones
≤
100 mm
Stones
25%
≤
Poor
PI
<
12%
DD
<
95%
Stones
<
5%
Stones
>
100 mm
Very poor
PI
10%
DD
90%
Stones
25%
Stones
120 mm
<
<
>
>
17.9 Frequency of testing
•
The frequency of testing is based on the size of the area and project, uniformity
of material and overall importance of the layer being tested.
Table 17.9
Guidelines to frequency of testing.
Test
Field density
Grading and plasticity index
Frequency for large
For selected material imported to
1 test per 2000 m
3
at selected
scale operations
site - Not less than
source before transporting to
a) 1 test per 1000 m
3
, and
site.
b) 4 tests per visit
1 test per 1000 m
3
for using
c) 1 test per 250 mm layer per
locally available material on
material type per 4000 m
2
site
For on site material imported - Not
less than
a) 1 test per 500 m
3
, and
b) 3 tests per visit
c) 1 test per 250 mm layer per
material type per 2000 m
2
Frequency for medium
Not less than
1 test per 500 m
3
at selected
scale operations eg
a) 1 test per 250 m
3
, and
source before transporting to
residential lots
b) 2 tests per visit, and
site
c) 1 test per 250 mm layer per
1 test per 250 m
3
for using
material type per 1000 m
2
locally available material on
site
Frequency for small scale
Not less than
1 test per 100 m
3
, at selected
operations using small
a) 1 test per 2 layers per 50 m
2
, and
source before transporting to
or hand operated
b) 1 test per 2 layers per 50 linear m
site
equipment eg backfilling,
1 test per 50 m
3
, for using
confined operations,
locally available material on
trenches
site
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