The Standard & Modified Proctor Density Tests

e) mixing tools, pans, moisture containers, etc.
f) oven for drying moisture content samples.
PROCEDURE (Standard Test):
1. Either mix 4 kg of sand and 400 g of bentonite or if the soil is pre-mixed take about 4½ kg. Break
up any lumps in the sample and mix it thoroughly.
2. Add about 9.5% water to the sample or as given by the instructor and mix thoroughly until all the
water is uniformly absorbed.
3. Weigh the empty mould without the collar or base and record its mass.
4. With the collar attached to the mould, compact a specimen in three equal layers to get a total
compacted depth of about 130 mm with 25 uniformly distributed blows of the rammer per layer.
During compaction the mould should rest directly on the concrete floor of the lab and not in the
mixing pan.
5. Remove the collar from the mould and strike off the soil with the straight edge even with the top
of the mould. Weigh the mould and the soil and record their mass. Subtract the mass of the
mould from the specimen and multiply by 1060 and record the result as the wet density of the
compacted specimen in kg/m 3 .
6. Remove the soil from the mould using the arbour press. Obtain a moisture content sample of
about 120 g from the centre of the specimen, weigh and place in the oven to dry.
7. Break up the sample and remix with the material that was not used in the test and add
approximately 2% more water. Remix and repeat the compaction procedure and obtain the
moisture content of the sample. This procedure is repeated again and again until two successive
decreases in the wet density of the compacted soil are observed. A minimum of 5 points are
normally required to plot the moisture density curve.
CALCULATIONS (Standard Test):
1 3
Wet density: (The volume of the 4" mould is m )
1060
where
ρ = M x 1060
ρ = wet density in kg/m 3
M = mass of wet soil contained in the mould in kg (does not include the mould)
2