17-01-2014, 03:10 PM
MAXIMUM DRY DENSITY AND OPTIMUM MOISTURE CONTENT
AIM
To determine the maximum dry density and the optimum
moisture content of soil using heavy compaction as per IS: 2720
(Part 8) - 1983.
PREPARATION OF SAMPLE
A representative portion of air-dried soil material, large enough to
provide about 6kg of material passing through a 19mm IS Sieve
(for soils not susceptible to crushing during compaction) or about
15kg of material passing through a 19mm IS Sieve (for soils
susceptible to crushing during compaction), should be taken.
This portion should be sieved through a 19mm IS Sieve and the
coarse fraction rejected after its proportion of the total sample
has been recorded.
Aggregations of particles should be broken down so that if the
sample was sieved through a 4.75mm IS Sieve, only separated
individual particles would be retained.
PROCEDURE
A) Soil not susceptible to crushing during compaction –
i) A 5kg sample of air-dried soil passing through the 19mm IS
Sieve should be taken. The sample should be mixed
thoroughly with a suitable amount of water depending on the
soil type (for sandy and gravelly soil - 3 to 5% and for
cohesive soil - 12 to 16% below the plastic limit). The soil
sample should be stored in a sealed container for a
minimum period of 16hrs.
ii) The mould of 1000cc capacity with base plate attached,
should be weighed to the nearest 1g (W1 ). The mould
should be placed on a solid base, such as a concrete floor
or plinth and the moist soil should be compacted into the
mould, with the extension attached, in five layers of
approximately equal mass, each layer being given 25 blows
from the 4.9kg rammer dropped from a height of 450mm
above the soil.