Objective
To determine moisture content and dry density relationship using heavy compaction or modified compaction method as per IS-2720-Part-8.
Apparatus
• Metal mould (volume = 1000 cm3)
• Balance (capacity = 10 kg, least count = 1g)
• Oven (105 to 1100C)
• Sieve (19 mm)
• Metal rammer (weight = 4.9 kg)
Procedure
- Dry the soil sample by exposing it to air or sun light.
- Sieve the air dried soil through 19 mm sieve.
- Add suitable amount of water with the soil and mix it thoroughly. For sandy and gravelly soil add 3% to 5% of water. For cohesive soil the amount of water to be added should be 12% to 16% below the plastic limit.
- Weigh the mould with base plate attached to the nearest 1g. Record this weight as ‘W1’.
- Attach the extension collar with the mould.
- Compact the moist soil into the mould in five layers of approximately equal mass, each layer being given 25 blows, with the help of 4.9 kg rammer, dropped from a height of 450 mm above the soil. The blows must be distributed uniformly over the surface of each layer.
- After completion of the compaction operation, remove the extension collar and level carefully the top of the mould by means of straightedge.
- Weigh the mould with the compacted soil to the nearest 1 g. Record this weight as ‘W2’.
- After weighing remove the compacted soil from the mould and place it on the mixing tray. Determine the water content of a representative sample of the specimen. Record the moisture content as ‘M’.
- Broken up the remainder of the specimen and repeat step 5 to step 9 by adding suitable increment of water to the soil. For sandy and gravelly soils the increment in general is 1% to 2%. For cohesive soils the increment in general is 2% to 4%.
- The total no. of determinations made shall be at least five, and the moisture contents should be such that the optimum moisture content, at which the maximum dry density occurs, is within that range.
Calculation
Bulk density, γb in g/cm3 of each compacted specimen is calculated from the following equation.
γb = (W2-W1)/Vm
where,
W1 = Weight in g of mould + base plate
W2 = Weight in g of mould + base plate + soil
Vm = Volume of mould i.e. 1000 cm3.
Dry density, γd in g/cm3 of each compacted specimen is calculated from the following equation.
γd = 100 γb/(100+M)
Where,
γb = Bulkdensity of soil in g/cm3.
M = Moisture content of soil
Graph
The dry densities, γd , obtained in a series of determinations is plotted against the corresponding moisture content ‘M’. A smooth curve is then drawn through the resulting points and the position of the maximum on this curve is determined, which is called maximum dry density (M.D.D). And the corresponding moisture content is called optimum moisture content (O.M.C.).
If the MDD=4.94 and OMC = 7.375 therefore which type of soil can we classified into
Can you please explain sir..
Can you share the inference of modified proctor test..
Over water supply DI line, shall we use standard proctor test
here you have written heavy compaction test but the blow is 25.
It’s very confusing.
If small mould of dia 100 mm is used then no. Of blows are 25
Nd if 150 mm mould is used no. Of blows become 55
if we have soil sample 9000 kg and 1st time i mix water 2% and then we make 2nd trail then how much water i added in this soil sample how to calculate the water i mean calculate weight of soil 9000 kg or minus which soil i take its for moisture content
Will water content of soil increases with increase in quantity of water
Thanks for your nice explanation, i have a question. at site we can got the compaction of soil more than what we have got from laboratory .
how to change the dimensions of the rammer without changing the compactive effort?
In which type of soil we provide heavy compaction or light compaction
What are the precautions in this experiment ?
Sir, my lab results of murrum MDD-1.43 & OMC-28 , can u explain the me the about results are confirming or not
the amount of water for sandy soil is 4 % and for clayey soil 8%.
I m confused about it I heard that modified proctor has 56 blows but here u shared that it has 25 blows
56 blow for heavy and 25 blow for light
It is fascinating
ur explications are understandable
thank you to share ur knowledge
I am interested
thanks
Infinite thanks Sir..Really ur way of explainaing n presentations are excellent and extremely easy to understand..our all best wishes with u always sir..thank u once again for sharing ur valuable knowledge….