Proctor density test on soil in laboratory , Maximum dry density & optimum moisture content

Determination of water content and dry density relation using light compaction method 

 SCOPE:

To determine the optimum water content (OMC)at which a soil can be compacted so as to yield the maximum density the maximum dry density(MDD) for a given compactive effort will usually produce a sample whose saturated strength is near maximum. 

 IS CODE: 

 IS:2720-part VII;1980.

Determination of water content and dry density relation using light compaction. 

This standard lays down the method for the determination of of the relation between the water content and dry density of soil using light compaction. In this test at 2.6 kg rammer falling through a height of 310 mm is used. 

 APPARATUS: 

 1.Cylindrical metal mould
 2.sample extruder 
 3.balance 
 4.oven 
 5.container 
 6.steel straightedge 
 7.sieve 
 8.mixing tool 
 9.metal rammer 

 SHORT PROCEDURE:

 A 3kg sample of air dried soil passing the 20mm IS test sieve should be taken. 

The sample should be mixed to thoroughly with a suitable amount of water depending on the soil type. The mould with baseplate attached should be weighted to the nearest 1g. 

The mould should be placed on solid base, such as a concrete floor or plinth and the moist soil should be compacted into the mould, with the extension attached, in three layers of approximately equal mass, each layer being given 25 blows from the 2.6 kg rammer is dropped from a height of 310 mm above the soil. 

The blows should be distributed uniformly over the surface of each layer. After then the extension should be removed and the compacted soil should be leveled off carefully to the top of the moild by means of the straightedge. 

The mould and soil should then weighed to nearest 1g. 

Repeat the above same procedure for increment of water in same soil in other 3kg of soil sample.(ex.8%,10%,12%)

 CALCULATIONS: 

 1)bulk density            
Where, 
 M1= weight of empty mould and base (g),
 M2= weight of mould,base and soil (g), 
 Vm= volume of mould ( ml). 

 2.dry density 
 Where,
 W= moisture content of compacted soil (%)


 Note; 
 ✓ The dry densities ubtained in a series of determinations should be plotted against the corresponding moisture content W. 
 ✓ A smooth curve should be drawn through the resulting points and the position of the maximum on this curve should be determined. 
 ✓ Dry density in gram per ml corresponding to the maximum point on the moisture content curve shall be reported as the maximum dry density (MDD).
 ✓ The percentage moisture content corresponding to the maximum dry density on the the moisture content should be reported as the optimum moisture content(OMC). 
 ✓ To achieve the maximum density of any soil at site, it shoud to be campact by its OMC value.