Aim: To determine the relationship between water content and dry density of the given soil
and then to determine optimum moisture content and maximum dry density.
Equipment & Accessories: Cylindrical metal mould of capacity 1000cc., metal rammer
weighing 2.6 kg, and having a drop of 31cm, steel straight edge, balance, oven, water content container, mixing equipment, sample extruder, IS Sieve (20mm & 4.75mm).
Fig. 1 Standard proctor compaction apparatus
Theory: Compaction is a process by which the soil particles are artificially rearranged and
packed together into a closer state by mechanical means to decrease the porosity. In 1933, proctor showed that there existed a definite relationship between the soil water content and degree of dry density to which the soil might be compacted. Optimum water content may be defined as the water content at which a particular soil attains a maximum dry density for a specific amount of compaction energy. In the field, soils are compacted with addition of optimum moisture content to achieve the maximum dry density obtained in the laboratory.
Procedure:
Take about 20kg of air dried and mixed soil for 1000cc mould (10cm dia) or 45 kg for 2250cc mould (15cm dia).
Sieve this soil through 20mm and 4.75mm sieve.
STANDARD PROCTOR COMPACTION TEST
IS : 2720 (Part 7) - 1980Aim: To determine the relationship between water content and dry density of the given soil
and then to determine optimum moisture content and maximum dry density.
Equipment & Accessories: Cylindrical metal mould of capacity 1000cc., metal rammer
weighing 2.6 kg, and having a drop of 31cm, steel straight edge, balance, oven, water content container, mixing equipment, sample extruder, IS Sieve (20mm & 4.75mm).
Fig. 1 Standard proctor compaction apparatus
Theory: Compaction is a process by which the soil particles are artificially rearranged and
packed together into a closer state by mechanical means to decrease the porosity. In 1933, proctor showed that there existed a definite relationship between the soil water content and degree of dry density to which the soil might be compacted. Optimum water content may be defined as the water content at which a particular soil attains a maximum dry density for a specific amount of compaction energy. In the field, soils are compacted with addition of optimum moisture content to achieve the maximum dry density obtained in the laboratory.
Procedure:
Take about 20kg of air dried and mixed soil for 1000cc mould (10cm dia) or 45 kg for 2250cc mould (15cm dia).
Sieve this soil through 20mm and 4.75mm sieve.
STANDARD PROCTOR COMPACTION TEST
IS : 2720 (Part 7) - 1980Aim: To determine the relationship between water content and dry density of the given soil
and then to determine optimum moisture content and maximum dry density.
Equipment & Accessories: Cylindrical metal mould of capacity 1000cc., metal rammer
weighing 2.6 kg, and having a drop of 31cm, steel straight edge, balance, oven, water content container, mixing equipment, sample extruder, IS Sieve (20mm & 4.75mm).
Fig. 1 Standard proctor compaction apparatus
Theory: Compaction is a process by which the soil particles are artificially rearranged and
packed together into a closer state by mechanical means to decrease the porosity. In 1933, proctor showed that there existed a definite relationship between the soil water content and degree of dry density to which the soil might be compacted. Optimum water content may be defined as the water content at which a particular soil attains a maximum dry density for a specific amount of compaction energy. In the field, soils are compacted with addition of optimum moisture content to achieve the maximum dry density obtained in the laboratory.
Procedure:
Take about 20kg of air dried and mixed soil for 1000cc mould (10cm dia) or 45 kg for 2250cc mould (15cm dia).
Calculate the percentage retained on 20mm and 4.75mm sieves and passing from 4.75mm sieve.
Do not use the soil retained on 20mm sieve.
Use a 10cm dia mould if percentage retained on 4.75mm sieve is less than 20 or use a mould of 15cm diameter if percentage retained on 4.75mm sieve is more than 20.
Mix the soil retained on and passing through 4.75mm sieve thoroughly.
Take about 2.5 kg of the soil for 1000cc (6kg. for 2250cc mould)
Add water to it to bring its moisture content to about 4% in coarse grained soil and 8% in fine grained soils.
Clean the mould and apply grease inside and also to the base plate. Weigh the mould with base plate and fit the extension collar.
Compact the wet soil in three equal layers by rammer of mass 2.6kg having free fall of 31cm with 25 evenly distributed blows on each layer for 10cm diameter mould and 56 blows for 15cm diameter mould.
Remove the collar and trim off the soil flush with top of the mould.
Clean the outside of the mould and base plate, weigh the mould with soil and base plate.
Take a representative sample for water content determination.
Repeat the above procedure till the weight of the soil decreases with increase in water content and tabulate as follows:
Observations & Calculations
Wt. of mould = 1933g Volume of mould, V = 944 g
Table. 1 Calculation of dry density
Sample no 1 2 3 4 5 Mass of compacted soil and mould, g 3457.2 3721.2 3909.0 3782.5 3715.2 Mass of empty mould, g 1933 1933 1933 1933 1933 Mass of wet soil,
M g 1524.2 1788.2 1976 1849.5 1782.2
Mass of empty container + Wet soil, M2 46.85 47.18 45.32 48.66 45.15 Mass of empty container + Dry soil, M3 45.82 46.15 43.83 47.28 44.27 Moisture content = ( − ) × 100 − 8.2 10.6 12.8 15.65 17.4 Dry Density,d= 1.49 1.71 1.86 1.69 1.61
Graph: Plot the water content on x-axis and dry density in y-axis, draw the smooth curve,
called compaction curve.
Fig.2 Dry density vs moisture content relationship
Result:
Maximum dry density: 1.88 g/cc Optimum moisture content: 13%
QUESTIONS
1. What is compaction? Why is it done?
Standard Proctor Compaction Test
1.40 1.50 1.60 1.70 1.80 1.90 2.00 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Moisture Content (%) D ry D ens it y, g/ cc
2. Differentiate between compaction and consolidation of soils?
3. What is maximum dry density of soils at its OMC? Does it mean that density can not be more than this for a given soil?
4. What is optimum moisture content?
5. What is meant by dry side and wet side of optimum? Which side is preferred in field compaction? Explain
6. What is the meaning of field compaction control?