Standard Proctor Test of Soil is required to find out MDD and OMC of soil. We described procedure of standard proctor test or soil compaction test as per IS Code with calculations.
What is Standard Proctor Test?
By standard proctor test, we determine the moisture content on which related soil or any material get maximum compaction. This test is called the maximum dry density test too.
Why Proctor Test Required?
To know the exact amount of water to compact the related soil or any material on maximum density.
In roadwork or highway construction while laying embankment, subgrade or any other material bed we have to maintain this water content in soil or any material to get maximum compaction after rolling.
Standard Proctor Test IS code
Standard proctor test IS code is IS 2720 part 7 and part 8.
IS 2720 part 7 for lightweight compaction.
IS 2720 part 8 for heavyweight compaction.
Standard Proctor Test ASTM
Standard proctor test ASTM D698.
Modified proctor test ASTM D1557.
Standard Apparatus Test Apparatus
Following we use for proctor compaction test apparatus
- Two-cylinder mould, first – dia – 100 mm and volume -1000 cc
second – dia – 150 mm and volume – 2250 cc.
- Rammer for compaction, the weight of falling rammer – 4.89 kilograms.
falling distance – 450 mm.
Volume of Mould in Standard Proctor Test
There are two types of mould as per volume.
- 1000 cc mould for finer materials.
- 2250 cc mould for coarser materials.
- Two weighing balance,
first – capacity minimum 15 kilograms and least count 1 gram.
second – capacity minimum 200 gram and least count 0.01 gram.
- Containers to take soil samples for moisture content.
- Hot air oven to maintain the temperature between 100 to 110-degree centigrade.
- Straightedge made from steel to struck off extra materials from the top of mould and level, the length should be near about 300 mm.
- Sieves 37.5 mm, 19.0 mm, 4.75 mm.
- Tray (non-absorbent) to mix material with water.
- Hand gloves.
Standard Proctor Test procedure
Modified Proctor Test
If soil sample having up to 40 mm coarse particles size then use 2250 cc volume mould.
If soil sample having up to 20 mm coarse particles size then use 1000 cc volume mould.
We have taken here 2250 cc mould for example.
- If the sample is not dry then keep it ( near about 10 kg ) in the oven for 24 hours on 100 to 110-degree centigrade.
- Keep out the sample after 24 hours and allow it to be cool in the atmosphere until it’s temperature reaches similar atmosphere temperature.
- Sieve this sample by 37.5 mm sieve and take passed material through a sieve for proctor test.
- If you are taking soil for proctor then take 5.5 to 6.0 kg. If so many stones in the soil sample then you can take 6.5 kg.
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- Keep the 2250 cc volume mould with collar clean and ready.
- If soil is clayey soil then start adding water from 4 percent of soil weight. If soil you have taken 6000 gram then water weight will be =6000 * 4% = 240 gram.
- If soil is gravel soil then start adding water from 2 percent of soil weight. If soil you have taken 6500 gram then water weight will be = 6500 * 2% = 130 gram.
- After proper mixing, the water with soil, distribute in 5 approximately equal part in-tray. So you will remember how many layers have been done.
- Pour first part in the mould and give 55 blows with a rammer.
- Rammer must fall freely and uniformly distributed on the soil in the mould.
- Then pour the second part and repeat the same.
- You have to compact the last layer as the top of the compacted soil layer will be near about 6 mm higher than the top of mould.
- Remove the collar.
- Then struck off this extra soil layer from the top of mould and level by a straight edge.
- Clean mold if any soil stick on the outside or bottom side of mould.
- Take and note down the weight of soil and mould.
- Remove soil from mould and take a soil sample for moisture content. Do not take a soil sample for moisture from the top layer. It should not less than 50 gram.
- Take the weight of soil moisture sample with a container in second weighing balance with accuracy 0.01 gram.
- Spread the soil in a tray after removing from mould and brakes the soil lumps by wooden hammer or by hand. Do not use metal hammer otherwise it will break stones.
- Increase the water 2 percent and again 5 layers, 55 blows on each layer.
- Increase the water 2 percent until the soil + mould weight decreases.
Standard Proctor Test Lab Report
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Standard Proctor Test Graph
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For better learning we have prepared a video, you can watch.
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Standard Proctor Test Video
Standard Proctor Test Report, Calculation and Graph Video
Viva Questions on Standard and Modified Proctor Test
Q.1 What is the difference between standard proctor test and modified proctor test?
Ans. Now, these days in India many of clients and consultants are recommending modified proctor instead of standard proctor test.
Because the modified proctor test gives a more accurate value than standard proctor test result.
Such as It decreases the optimum moisture content of soil of material and gives more compaction ( density). In modified proctor we use more blows and rammer falling height than standard proctor.
That’s why everyone prefer modified proctor now.
Q.2 What is the IS code for light-weight proctor and heavy-weight proctor?
Ans. For light-weight proctor IS 2720 part 7,
for heavy-weight proctor IS 2720 part 8.
Q.3 What sieves are required for any soil proctor test?
Ans. These sieves are required for 37.5mm, 19.0mm and 4.75mm.
Q.4 Which water percentage we should add to start proctor test of soil?
Ans. If you are going to test
a clayey soil – start from 4 %
for sandy soil – start from 2 %
for gravely soil – start from 2 or 3 %
for pond-ash – start from 16 %
for GSB – start from 2%
for WMM – start from 2 %.
These values you can’t find in any IS Codes.
Just doing so many tests during my 10-year experience I got it.
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Both the standard Proctor test and the modified Proctor are used to verify compression.
At the time of the war, larger and larger aircraft were loading up the runways, and they needed a stricter method of measuring compaction.
This compresses a soil sample at different moisture content and determines how much it can be compacted.
Then you tell the field players that they have to reach part of that maximum.
The Proctor Soil Density Test is used to determine the maximum dry density for each soil on which you may be building.
While standard soil compaction tests can be performed on site for preliminary results, the Proctor compaction test is typically performed in the laboratory.
In addition, labs have access to a wider selection of test types, such as:As static tests and vibration tests to achieve the most accurate results.
The soil tested in the lab is unlikely to be identical to the soil being tested on the field (because the soil is not completely uniform in nature).
There could be an error in the lab tests or in the field tests.
A little more understanding of the Proctor test provides some additional information.
Therefore, Proctor modified soil testing is generally a too stringent standard for earthworks associated with low level commercial, residential and industrial buildings.
It is probably a good idea for you to complete a basic soil mechanics and soil laboratory if this is available in your area.
Get a copy of each standard (ASTM D698 for Standard Proctor and ASTM D1557 for modified Proctor) and read it through.
Compaction has little to do with the load-bearing capacity of the soil, as it is usually associated with surface or very near-surface conditions.
There are some tests that give you an idea of the carrying capacity, eg. Eg plate load tests.
For larger structures, where geotechnical engineers are the norm, I agree that the tests are probably the norm and necessary.
Even in larger projects where a geotech engineer is deployed, compaction testing seems to be another practically avoidable step unless we encounter questionable soils.
For the last two decades I’ve been working with this company, since we’ve NEVER encountered any known Proctor test, I do not see any urgency or necessity when the allowable soil carrying capacity is achieved.
Some of this has already been addressed, but I will just add my understanding to the conversation.
Modern compaction equipment can compact soil at a reasonable cost to the changed proctor density values. For this reason, nowadays generally modified proctor densities are mentioned.
Each of these soil samples (for a standard Proctor test) is then crushed at a weight of 5.5 pounds, falling 20 inches from a height of 12 inches.
The results shown in the graph are generally consistent with field observations of common sense.
If too much moisture gets into the ground, as is the case after heavy rains, the soil simply does not compact well.
The graph shows that the highest density in this test is 118 pounds per cubic foot.
Collect all minus 4 sieve materials (about 6 lb) in a large pan.
Evenly compact each layer 25 times with the standard Proctor Hammer before pouring in each additional layer of loose soil.
Place the moisture box with soil in the oven to dry it to a constant weight.
Learn about the rock formation at the beginning of a project and familiarize yourself with the basic characteristics of the rock (ease of excavation, slope stability, drainage, groundwater flow, etc.).
When assessing the stability of the ground slope, remember that water increases weight and reduces soil strength (a double hit).
When dealing with soil compaction problems, always keep in mind that the soil sample tested in the laboratory matches the soil being compacted in the field.
The best method for dealing with wet, muddy or dry, dusty conditions depends on the type of soil.
The requirements for compaction and methods for backfilling and embankment change for different soil types.
Soil is often the hardest to predict and the hardest to work with on a construction project.
In contrast to steel, aluminum, glass, cement, etc., the building material soil is generally not homogeneous (the material properties vary greatly within a sample).
Coarser materials are returned to determine the particle size and, in some cases, proportional re-addition to the final test specimens.
At this stage, sample separation and coarse particle size determination are often performed simultaneously.
Four or five samples are prepared for the densification points with increasing moisture content and the estimated optimum water content.
During the design of a constructed filling, shear, solidification, permeability or other tests require the preparation of test specimens by compacting at a certain water content to a certain unit weight.
It is common to first determine the optimum water content (w opt) and the maximum dry weight (g d, max) by a densification test.
The specimens are compacted at a selected moisture content (w), either wet or dry, of optimum (w opt) or optimum (w opt), and at a selected dry weight, based on a percentage of maximum dry weight (gd), max)
Compression is the process of compaction of the soil by reducing air pores.