PROCTOR COMPACTION TEST

Objective:

Determination of the dry density and moisture content relationship of a soil

Equipment:

Cylindrical mould and accessories, Rammer of 2.6kg, Sample extruder, Balance (1g

accuracy), Mixing Tray, Straight edge knife, Moisture meter, Graduated cylinder.

Procedure:

1. Take the 3 kg soil sample passing through the 4.75mm sieve in a mixing tray.

2. Measure the hygroscopic water content of the soil sample by moisture meter.

3. Weigh the mould without base plate and apply grease lightly on the interior surfaces.

Fix the collar on the top of mould.

4. Add water to the soil to bring its moisture content to about 14% and then mix it

thoroughly by hand until there should not find any lumps in the soil.

5. For light compaction, compact the moist soil in three equal layers using a rammer of

mass 2.6 kg and having free fall of 31 cm. Distribute the blows evenly, and apply 25

blows in each layer. Ensure that the last compacted layer extends above the collar

joint.

6. Rotate the collar so as to remove it, and trim the excess soil and level off the top of

the mould. Any small cavities should be filled up with soil.

7. Weigh the compacted soil with mould and note down the reading.

8. Fit the mould on to the extruder and jack out the soil. Break up the sample on a tray.

9. Add 3% increment of water to soil sample and repeat the procedure again. Mix in

water thoroughly for each time of water added

10. Repeat the compaction process until a peak value of maximum dry density reached

followed by a few samples of lesser compacted soil masses.

Observations and Calculations:

Volume of mould V (cm³) = 1000

Mass of the mould W (g) = 2142

Reading shown in moisture meter R = 7.4

Hygroscopic water content = (100R) ÷ (100-R)

Hygroscopic water content of the soil = 8%

S.No Hygroscopic

water content

(%)

Percentage

Water

Added (%)

Total

Water

Added

(ω) (%)

Weight of

Soil +

Mould

(gm)

Weight

of Soil

(W)

(gm)

Bulk

Density of

Soil (γ)

(gm/cc)

Dry Density

of Soil (γd)

(gm/cc)

Void

Ratio (e)

1 8 6 14 3757.5 1615.5 1.6155 1.41710526 0.862953

2 8 9 17 3945 1803 1.803 1.54102564 0.713145

3 8 12 20 4027 1885 1.885 1.57083333 0.680637

4 8 15 23 4124 1982 1.982 1.61138211 0.638345

5 8 18 26 4118 1976 1.976 1.56825397 0.683401

6 8 21 29 4075 1933 1.933 1.49844961 0.761821

Water content (%) 100% line theoretical

maximum Dry

density (g/cc)

90% line theoretical

maximum Dry

density(g/cc)

80% line theoretical

maximum Dry

density(g/cc)

14 1.92757 1.87145 1.80574

17 1.82219 1.76156 1.69122

20 1.72774 1.66386 1.59036

23 1.64260 1.57643 1.50085

26 1.56546 1.49773 1.42088

29 1.49524 1.42651 1.34900

1.4

1.5

1.6

1.7

1.8

1.9

2

14 16 18 20 22 24 26 28 30

DR

Y D

ENSI

TY

WATER CONTENT

DRY DENSITY VS WATER CONTENT

Dry Density Vs Water Content 100% Saturation Line

90% Saturation Line 80% Saturation Line

0.6

0.65

0.7

0.75

0.8

0.85

0.9

1.4 1.45 1.5 1.55 1.6 1.65

Void

Rati

o

Dry Density in g/cc

Void Ratio Vs Dry Density

Results:

The maximum dry density of soil sample is 1.61 g/cc and the optimum moisture

content is 23%.

Discussion:

Initially with addition of water dry density increases as water acts as a lubricant, with

compaction soil particle come closer. So volume decrease, it achieves maximum value

when air volume becomes minimum. After addition dry density decreases as water occupy

soil particles.

By compaction be can improve shear strength, compressibility, permeability of the soil.

Conclusion:

From the shape of the graph it can be concluded that the soil might be a low plastic

clay and the optimum moisture content of the soil was 23% and if this soil is to be used in a

field then the density of the soil at the field should be almost equal to 1.61 g/cc

References:

V.N.S. Murthy, Soil mechanics and foundation engineering.

Braja M.Das, Principles of Geotechnical Engineering fifth edition.