DHARMCOMPACTION OF SOIL 427
12.5.1Standard Proctor Test (AASHO Test)
This test was developed by R.R. Proctor (1933) in connection with the construction of earth
dams in California (U.S.A.).The apparatus for the test consists of (i) a cylindrical mould of
internal diameter 102 mm and an effective height of 117 mm, with a volume of 0.945 litre, (ii)
a detachable collar of 50 mm effective height (60 mm total height), (iii) a detachable base plate,
and (iv) a 50 mm diameter metal rammer of weight 25 N, and a height of fall of 300 mm,
moving in a metallic outer sleeve (Fig. 12.4).
60 50102(^117) Detachable
base
plate
Cylindrical
mould
Collar
Handle
(spherical or cylindrical)
Sleeve
Rod
Rammer
(weight 25 N)
50
Height of
fall 300
Note:
I. All dimensions are in mm.
- Original dimensions in FPS
units are given to the
nearest mm.
Fig. 12.4 Apparatus for standard proctor test
The Test Procedure Consists of the Following Steps:
(a) About 30 N of air-dried soil passing 20 mm sieve is taken.
(b) A reasonable amount of water is added to the soil and it is thoroughly mixed.
(c) The mould is filled with this moist soil in three equal layers to give a total com-
pacted depth of 130 mm. Each layer is compacted by giving 25 blows with the stand-
ard rammer, pulling the rammer in the sleeve to the maximum height and then
allowing it to fall freely. The position of the rammer is changed each time to distrib-
ute the compactive energy evenly to the soil. Each layer is raked with a spatula
before placing fresh soil to provide proper bond.
(b) The collar is removed and the extra soil trimmed off to the top of the mould and the
weight of the mould obtained. The wet weight (W) of the soil is got by subtracting
the weight of the empty mould.
The bulk unit weight (γ) of the soil is obtained by dividing the wet weight of soil by
the volume of the soil (V) which is the same as that of the soil.
γ = W/V
(e) A representative sample of the wet soil is taken and the moisture content (w%)
determined in the standard manner through oven-drying.