THE STANDARD PROCTOR AND THE MODİFİED PROCTOR TESTS

Purpose:

This laboratory test is performed to determine the relationship between the moisture content

and the dry density of a soil for a specified compactive effort. The compactive effort is the

amount of mechanical energy that is applied to the soil mass. Two types of compaction tests

are routinely performed: (1) The Standard Proctor Test, and (2) The Modified Proctor Test.

Reference:

ASTM D 698 - Standard Test Methods for Laboratory Compaction

ASTM D 1557 - Standard Test Methods for Laboratory Compaction

Equipment: Proctor mould with a detachable collar assembly and base plate.

Drop rammer

a) Standard Test: 24.5N rammer falling 0.305m

b) Modified Test: 44.5N rammer falling 0.46m

Sample Extruder.

A sensitive balance.

Straight edge.

Squeeze bottle

Mixing tools such as mixing pan, spoon, trowel, spatula etc.

Moisture cans.

Drying Oven

10.#4 sieve,

Graduated cylinder,

Test Procedure

(1) Depending on the type of mold you are using obtain a sufficient quantity of air-dried soil

in large mixing pan. For the 101,6mm mold take approximately 4,5kg, and for the 152,4mm

mold take roughly 6,75kg. Pulverize the soil and run it through the # 4 sieve.

(2) Determine the weight of the soil sample as well as the weight of the compaction mold with

its base (without the collar) by using the balance and record the weights.

(3) Compute the amount of initial water to add by the following method: (a) Assume water

content for the first test to be 8 percent. (b) Compute water to add from the following

equation:

water to add (in ml) = (soil mass in grams) 8/ 100

or add approximate amount of water to increase the moisture content by

about 5%.

(4) Measure out the water, add it to the soil, and then mix it thoroughly into the soil using the

trowel until the soil gets a uniform color (See Photos B and C).

(5) Assemble the compaction mold to the base, place some soil in the mold and compact the

soil in the number of equal layers specified by the type of compaction method employed (See

Photos D and E) Place the first portion of the soil in the Proctor mould as

explained in the class and compact the layer applying 25 blows.

(6) Scratch the layer with a spatula forming a grid to ensure uniformity in

distribution of compaction energy to the subsequent layer. Place the

second layer, apply 25 blows, place the last portion and apply 25 blows.The

number of drops of the rammer per layer is also dependent upon the type of mold used. The

drops should be applied at a uniform rate not exceeding around 1.5 seconds per drop, and the

rammer should provide uniform coverage of the specimen surface. Try to avoid rebound of

the rammer from the top of the guide sleeve.

(7) The soil should completely fill the cylinder and the last compacted layer must extend

slightly above the collar joint. If the soil is below the collar joint at the completion of the

drops, the test point must be repeated. (Note: For the last layer, watch carefully, and add more

soil after about 10 drops if it appears that the soil will be compacted below the collar joint.)

(8) Carefully remove the collar and trim off the compacted soil so that it is completely even

with the top of the mold using the trowel. Replace small bits of soil that may fall out during

the trimming process (See Photo F).

(9) Weigh the compacted soil while it’s in the mold and to the base, and record the mass (See

Photo G). Determine the wet mass of the soil by subtracting the weight of the mold and base.

(10) Remove the soil from the mold using a mechanical extruder (See Photo H) and take soil

moisture content samples from the top and bottom of the specimen (See Photo I). Fill the

moisture cans with soil and determine the water content.

(11) Place the soil specimen in the large tray and break up the soil until it appears visually as

if it will pass through the # 4 sieve, add 2 percent more water based on the original sample

mass, and re-mix as in step 4. Repeat steps 5 through 9 until, based on wet mass, a peak value

is reached followed by two slightly lesser compacted soil masses.

Calculations:

(1) Calculate the moisture content of each compacted soil specimen .

(2) Compute the wet density in grams per cm3 of the compacted soil sample by dividing the

wet mass by the volume of the mold used.

(3) Compute the dry density using the wet density and the water content determined in step 1.

Use the following formula:

where: w = moisture content in percent divided by 100, and ρ = wet density in grams per cm3.

(4) Compute the dry unit weight in kN per m3 .

(5) Plot the dry unit weight values on the y-axis and the moisture contents on the x-axis. Draw

a smooth curve connecting the plotted points.

(6) On the same graph draw a curve of complete saturation or “zero air voids curve”. The

values of dry density and corresponding moisture contents for plotting the curve can be

computed from the following equation:

where:

yd= dry unit weight of soil (kN/m3)

Gs = specific gravity of the soil being tested (assume 2.70 if not given)

yw = unit weight of water (kN/m3)

S = moisture content in percent for complete saturation.

(7) Identify and report the optimum moisture content and the maximum dry unit weight..

Data And Graphics For Modified Proctor Test

MODIFIED PROCTOR TEST

Dry Unit Density (g/cm3)

Dry Unit Weight (kN/m3)

Moisture Content w(%)

Specific Gravity

Dry Unit Weight γd(kN/m3)

S=70% S=80% S=90% S=100%

1,873 18,37 9,3 2,64 19,17 19,82 20,35 20,79

1,910 18,74 12,8 2,64 17,47 18,21 18,83 19,36

1,803 17,69 15,5 2,64 16,34 17,13 17,80 18,38

1,699 16,67 18,7 2,64 15,19 16,02 16,72 17,34

1,641 16,10 21,1 2,64 14,42 15,27 16,00 16,63

Ydmax=18,52kN/m3 and WOPTİMUM=9,8% are obtained from The Dry unit curve.

Data And Graphics For Standard Proctor Test

STANDART PROCTOR TEST

Dry Unit Weight (g/cm3)

Dry Unit Weight (kN/m3)

Moisture Content w(%)

Gs

Dry Unit Weight γd(kN/m3)

S=70% S=80% S=90% S=100%

1,691 16,59 9,3 2,64 19,17 19,82 20,35 20,79

1,715 16,82 11,8 2,64 17,92 18,64 19,24 19,75

1,755 17,22 14,3 2,64 16,82 17,60 18,25 18,80

1,747 17,14 17,6 2,64 15,57 16,38 17,08 17,68

1,685 16,53 20,8 2,64 14,51 15,36 16,08 16,72

1,619 15,88 23 2,64 13,87 14,72 15,46 16,11

Ydmax=17,20kN/m3 and WOPTİMUM=15,1% are obtained from The Dry unit

curve.

SAND CONE TEST

Purpose:

This test method describes the procedure for determining the density of soil in place.

Reference:

AASHTO T 191 (Sand Cone)

Equipment

Sampling tools - hammer, chisel, trowel, large spoon, banister brush.

Containers - two 2.3 L size mason jars for which the tare weights are known.

Balance - 0.1 g accuracy

Sand Cone Density Apparatus(Figure1) - consisting of a double cone assembly having

a cylindrical valve between the cones with an orifice 12.7 mm in diameter. The upper

conewill be large enough to serve as a hopper to hold the density sand.

Density Sand - prepare a supply of air dried clean flowing sand which passes the 2.00

mm sieve and is retained on the 900 mm sieve. Thoroughly mix and preweigh 5000 g

samples and store in a clean dry place.

Procedure

1. Select the site to be tested at random or where sample for proctor has been taken.

2. Scrape smooth and remove all loose material at the location to be tested.

3. Start a small hole in the centre with a hammer and chisel.

4. Carefully enlarge the hole outwards and downwards with small hand tools until

sufficient material has been removed to fill the two 2.3 L mason jars.

5. Exercise extreme care in removing the material so as not to cause a disturbance to

surrounding material. Do not project the hole below the level of the material to be

tested.

6. Place all the material removed from the hole in the mason jars except Stone particles

larger than 18 mm. These stones will be replaced in the hole during the volume

measurement with density sand. The sealed jars will be taken to the lab and weighed

to the nearest gram and the tare weight subtracted. The result will be recorded as

"weight of material removed."

7. Carefully place and centre the sand cone device over the test hole with the valve

closed.

8. Place the 5000 g of density sand into the storage hopper of the sand cone device.

9. Turn on the valve.

10. If stone particles are to be replaced in the hole, allow a small quantity of sand to run

into the hole, close the valve, lift the apparatus, and partially imbed these particles into

the sand. Replace the device, turn on the valve, allow the sand to run until the test hole

and funnel are completely filled, and turn off the valve.

11. Remove the apparatus and remove the sand from the test hole and place in a large

cloth bag along with other used sand for later reclaiming.

12. Weigh the unused sand in the hopper to determine the amount of sand used in the test.

This weight of sand will be used to obtain the volume of hole and funnel.

13. Remove the soil cement mixture from the two mason jars and mix thoroughly together

and obtain a representative sample for moisture determination.

14. Place sample in a suitable tared pan and weigh.

15. Dry sample carefully to a constant weight.

16. Weigh sample and pan after cooling.

17. The difference between the wet and dry weights will be recorded as "weight of

moisture" and dry weight less weight of pan will be recorded as "weight of dry

sample."

Figure 1 Sand Cone Test Device

Calculation :

W1: The weight of the jar,the cone , sand

W2: The weight of the Moist soil excavted from hole

Wc: The weight of sand to fill the cone only

W3: The weight of the jar,the cone and remaining sand in the jar

W4: The Dry Weight of soil

w: water content(%)

y d(sand): Dry unit weight of the sand usedy d: Dry unit weight of soil

W4=W2/(1+w/100)

V=(W1 –W3- Wc)/y d(sand)

y d=W4/V

Data For Sand Cone Test:

 Volume of Hole (cm3)

Wet Mass

(g)

Dry Mass

(g)

Unit Density (g/cm3)

Dry Unit Density (g/cm3)

Unit Weight (kN/m3)

Dry Unit Weight (kN/m3)

Moisture Content w (%)

1.Test 938 1852 1642 1,974 1,751 19,37 17,17 12,8

2.Test 955 1873 1643 1,961 1,720 19,24 16,88 14,0

CONCLUSION:

Modified proctor : The values of Yd plotted against the corresponding moisture contents to

obtain the max. dry unit weight and the optimum moisture content for soil. From modified

proctor Dry Unit Weight Curve we obtained the values as; ydmax=18,52kN/m3 and

WOPT=9,8%. At that graph also we see Yzav (zero air void) which S=100% , is only place on

right of basic curve.

İf the data obtained from Modified proctor and Sand cone test are compared:

For test 1 :

Relative compaction=(17,17/18,52)*100=92,7%

For test 1:

Relative compaction=(16,88/18,52)*100=91,1%

So the required specifications for relative compaction.are provided

Optimum water content WOPT=9,8%.

WOPT±4=(5,8--13,8)

For test 1 water content provides the required specifications .But water content in the test 2 a

little over of max.Water content(13,8%). So , wait a little bit of water to dry.

Standard proctor test: The values of Yd plotted against the corresponding moisture contents

to obtain the max. dry unit weight and the optimum moisture content for the soil. From

standard proctor curve we obtained the values as; Ydmax=17,20kN/m3 and WOPT=15,1% . At

that graph also we see Yzav (zero air void) which S=100% , is only place on right of basic

curve.