TITLE:
TITLE: STANDARD PROCTOR COMPACTION TESTSTANDARD PROCTOR COMPACTION TEST
OBJECTIVES: OBJECTIVES:
To obtain the relationship between water content and dry unit weight by using the standardTo obtain the relationship between water content and dry unit weight by using the standard
proctor compaction test. proctor compaction test.
To determine the maximum dry unit weight and optimum water content.To determine the maximum dry unit weight and optimum water content.
INTRODUCTION INTRODUCTION
As described in Geotechnical Engineering, soil being a particulate medium
As described in Geotechnical Engineering, soil being a particulate medium contain pore spaces,contain pore spaces, which may or may not be filled with water. When the
which may or may not be filled with water. When the soil which has high void ratio, subject to externalsoil which has high void ratio, subject to external forces, the soil particles will be pushed to fill the voids spaces, as a results the soil will be subjected to forces, the soil particles will be pushed to fill the voids spaces, as a results the soil will be subjected to large deformations. Therefore, it is required to reduce the void spaces of partially saturated loose soil large deformations. Therefore, it is required to reduce the void spaces of partially saturated loose soil deposits to improve strength, reduce compressibility and conductivity.
deposits to improve strength, reduce compressibility and conductivity.
In the construction of highway embankments, earth dams, and many other engineering structures, In the construction of highway embankments, earth dams, and many other engineering structures, loose soils must be compacted to increase their unit weights. Compaction increases the strength
loose soils must be compacted to increase their unit weights. Compaction increases the strength characteristics of soils,
characteristics of soils, which increase the bearing capacitwhich increase the bearing capacity of foundations constructed over them.y of foundations constructed over them.
Compaction also decreases the amount of undesirable settlement of structures and increases the stability Compaction also decreases the amount of undesirable settlement of structures and increases the stability of slopes of embankments. Smooth- wheel rollers, sheepsfoot rollers,
of slopes of embankments. Smooth- wheel rollers, sheepsfoot rollers, rubber-tired rollers, and vibratoryrubber-tired rollers, and vibratory rollers a
rollers are generally used in the field for soil cre generally used in the field for soil compaction. Vibratory rollers are used mostly for theompaction. Vibratory rollers are used mostly for the densification of granular soils. Vibroflot devices are also used for
densification of granular soils. Vibroflot devices are also used for compacting granular soil deposits to acompacting granular soil deposits to a considerable depth.
considerable depth.
Standard proctor compaction test is to es
Standard proctor compaction test is to establish a relationship between dry density and moisturetablish a relationship between dry density and moisture content for a soil under controlled conditions. R.R. Proctor (1933) was the first t
content for a soil under controlled conditions. R.R. Proctor (1933) was the first t o develop a method ofo develop a method of assessing compacted fill that has
assessing compacted fill that has since become a universal standard and the since become a universal standard and the test is known as standardtest is known as standard proctor test. Standard proctor test is also known as light compaction test as per BIS. AA
proctor test. Standard proctor test is also known as light compaction test as per BIS. AASHO developed aSHO developed a modified test to give a higher standard of compaction and is known as modified proctor test. The same is modified test to give a higher standard of compaction and is known as modified proctor test. The same is also known as heavy compaction test as per BIS.
also known as heavy compaction test as per BIS. In the proctor compaction test, a soil s
In the proctor compaction test, a soil sample is compacted into a standard mold ample is compacted into a standard mold shown in figure 4.shown in figure 4. The total volume of the mold is 1000cm^3. Compaction of the soil is carri
The total volume of the mold is 1000cm^3. Compaction of the soil is carri ed out using the standarded out using the standard hammer shown in figure 4. The hammer has a 2.5kg ram, which can be lifted
THEORY THEORY
Compaction is the process of densification of soil by reducing air voids and the degree of compaction of a Compaction is the process of densification of soil by reducing air voids and the degree of compaction of a soil is measured in terms of its dry unit weight.
soil is measured in terms of its dry unit weight.
Determination of the dry density and moisture content of a soil
Determination of the dry density and moisture content of a soil under given compaction effort can beunder given compaction effort can be obtained from these equations shown below.
obtained from these equations shown below.
Bulk unit weight of the soil (
Bulk unit weight of the soil (ᵞᵞbulk)bulk)
ᵞᵞbulk bulk = (solid weight of soil inside the mold + moisture weight)/ volume of the mold= (solid weight of soil inside the mold + moisture weight)/ volume of the mold (Mass of the air within the voids of soil is neglected)
(Mass of the air within the voids of soil is neglected)
Dry unit weight of the soil (
Dry unit weight of the soil (ᵞᵞdry)dry)
ᵞᵞdry =dry =ᵞᵞbulkbulk
//
(1+ water content) (1+ water content)Water content = (Mass of water) / (dry mass of soil) % Water content = (Mass of water) / (dry mass of soil) %
Then the graph of the dry unit weight verses water content can be plotted. It gives a curve shown in Then the graph of the dry unit weight verses water content can be plotted. It gives a curve shown in figure 1, and from that curve
figure 1, and from that curve the maximum dry unit weight and optimum moisture content cthe maximum dry unit weight and optimum moisture content c an be found.an be found.
Figure
Figure 1. 1. Compaction Compaction curve curve Figure Figure 2. 2. Zero Zero air air void void lineline
If all the air of soil
If all the air of soil could be expelled by compaction, the soil would become fully saturated orcould be expelled by compaction, the soil would become fully saturated or the soil is at zer
the soil is at zero air voids condition. Practically it is impossible to attain o air voids condition. Practically it is impossible to attain full saturation by compaction,full saturation by compaction, the line showing the relationship between dry density and water content at saturation is called zero air the line showing the relationship between dry density and water content at saturation is called zero air void line or theoretical saturation line. Zero air void line is shown in figure 2.
APPARATUS APPARATUS
Cylindrical metal mold, which is fitted with a Cylindrical metal mold, which is fitted with a detachable base plate and removable extensiondetachable base plate and removable extension
collar (figure 4) collar (figure 4)
Metal rammer with 50mm diameter face, wMetal rammer with 50mm diameter face, weighting 24.4KN, sliding freely in a tube that controlseighting 24.4KN, sliding freely in a tube that controls
the height of drop to 300mm the height of drop to 300mm
Sample extruder (jack) for removing compacted material from tSample extruder (jack) for removing compacted material from the moldhe mold
Metal trayMetal tray
Balance sensitive to 0.1g and 0.01gBalance sensitive to 0.1g and 0.01g
Drying oven with temperature ranges from 105◦C to 110◦CDrying oven with temperature ranges from 105◦C to 110◦C
DesiccatorDesiccator
Trowel or scopeTrowel or scope
Straight edgeStraight edge
No 4 sieve (4.75mm) No 4 sieve (4.75mm)
Water sprayerWater sprayer
Figure 3. Test Apparatus Figure 3. Test Apparatus
Figure 4. Mold with Collar and Rammer Figure 4. Mold with Collar and Rammer
PROCEDURE PROCEDURE
The compaction mold was set to the base plate without the removable collar and weighed.The compaction mold was set to the base plate without the removable collar and weighed.
Then the removable collar was attached.Then the removable collar was attached.
Around 3kg representative specimen of the air dried soil Around 3kg representative specimen of the air dried soil sample was obtained and all the lumpssample was obtained and all the lumps
were broken. were broken.
The soil passed through no.4 sieve was collected to a tThe soil passed through no.4 sieve was collected to a t ray.ray.
Water was added to the soil and mixed thoroughly to get a homogeneous soil sample. The testWater was added to the soil and mixed thoroughly to get a homogeneous soil sample. The test
was started with a water
was started with a water content lower than the optimum.content lower than the optimum.
The mold assembly was placed on the ground and soil was added to the mold so that The mold assembly was placed on the ground and soil was added to the mold so that it was aboutit was about
half full. half full.
The soil was compacted by applying 25 blows of the rammer dropping from the controlled heightThe soil was compacted by applying 25 blows of the rammer dropping from the controlled height
of 300mm and ensured a uniform
of 300mm and ensured a uniform distribution of blows.distribution of blows.
A second approximately equal layer of soil was placed in the mold and compacted it with 25A second approximately equal layer of soil was placed in the mold and compacted it with 25
blows as before. blows as before.
Procedure was repeated with a third laProcedure was repeated with a third layer, which should bring the compacted soil level in theyer, which should bring the compacted soil level in the
extension collar to about 6mm above the level of the mold body. extension collar to about 6mm above the level of the mold body.
Extension collar was removed carefully. The excess soil Extension collar was removed carefully. The excess soil was cut and leveled off to the top of thewas cut and leveled off to the top of the
mold. The small cavities resulting from the removal of stones were filled with fine materials. mold. The small cavities resulting from the removal of stones were filled with fine materials.
Excess soil on the base plate was removed carefully using a brush and weighedExcess soil on the base plate was removed carefully using a brush and weighed
(Soil + mold + base plate). (Soil + mold + base plate).
The base was removed and the mold was set on the sample extruder, the sample was removedThe base was removed and the mold was set on the sample extruder, the sample was removed
from the mold. from the mold.
Some amount of Soil was collected from top, middle and bottom to determine the water Some amount of Soil was collected from top, middle and bottom to determine the water content.content.
Those Soil samples were put into the dry oven for water content determinatiThose Soil samples were put into the dry oven for water content determinati on.on.
The material in the tray was broken up and water was added to the soil with the sprThe material in the tray was broken up and water was added to the soil with the spr ayer. Then theayer. Then the
soil was mixed
soil was mixed thoroughlythoroughly..
The compaction process was kept repeating with increasing of the water The compaction process was kept repeating with increasing of the water content until five runscontent until five runs
had been made and soil became very wet and sticky. had been made and soil became very wet and sticky.
Figure
CONCLUSION CONCLUSION
Compaction of soil is an important process, as it helps it of achieve certain physical properties necessary Compaction of soil is an important process, as it helps it of achieve certain physical properties necessary for its proper behavior under loading: for example proper compaction of an earthen dam or a
for its proper behavior under loading: for example proper compaction of an earthen dam or a highwayhighway Embankment reduces the chances of its settlement, increases the shear strength of the soil due to its Embankment reduces the chances of its settlement, increases the shear strength of the soil due to its increased density and reduces the permeability of the soil.
increased density and reduces the permeability of the soil. The proctor compaction test was carried out suc
The proctor compaction test was carried out succefully and obtained a curve that satiscefully and obtained a curve that satisfied the objectives.fied the objectives. Clearly identified the relationship between the dry densit
Clearly identified the relationship between the dry densit y and the water content of a soil and ry and the water content of a soil and reasons toeasons to have that change was studied.
have that change was studied.
RFERENCES RFERENCES
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Proctor soil compactionProctor soil compaction
Available at:
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