SEMINAR ON
COMPACTIONBY
SUVADEEP DALAL
DEPARTMENT OF CIVIL ENGINEERING
IIT KHARAGPUR, KHARAGPUR
JANUARY 2012
What is Soil Compaction
Densification of soil by the application of mechanical energy.
Compaction Consolidation(i)Short term
process.(ii) Elastic
settlement occurs.
(iii) Reduction of air content at a given water content.
(iv) Soil is always unsaturated.
(i)Long term process
(ii) Plastic or permanent settlement occurs.
(iii) Expulsion of pore water from voids.
(iv) soil is completely saturated.
Method of Compaction
Cohessionless soils are compacted by dynamic method of compaction (vibration).
Cohessive soils are compacted by static compaction.
Objective of Compaction
Detrimental settlements can be reduced.
Soil strength and slope stability can be improved.
Bearing capacity of subgrade can be improved.
Undesirable volume change due to swelling , shrinkage may be controlled.
Factors Affecting Compaction
Water content Compacting effortMethod of compactionType of soilAddition of admixtures
Laboratory test
Proctor Test
Standard Proctor
Modified Proctor
Standard Proctor Test
Specification Description(i) Mass of hammer (i) 2.495 Kg(ii) Height of drop (ii) 304.88 mm(iii) Number of drops (iii) 25(iv) Number of layers (iv) 3(v) Volume of mould (v) 0.944*10^-3 m^3
Compactive effort = (2.495)*(9.81)*(304.88/1000)*(3)*(25)/(0.944*10^-3) = 592.7 KJ/m^3
Modified Proctor Test
Specification Description(i) Mass of hammer (i) 4.536 Kg(ii) Height of drop (ii) 457 mm(iii) Number of drops (iii) 25(iv) Number of layers (iv) 5(v) Volume of mould (v) 0.944*10^-3 m^3
Compactive effort = (4.536)*(9.81)*(457/1000)*(5)*(25)/(0.944*10^-3) = 2693 KJ/m^3
Procedure
Determination of Dry-density Moisture Content Relationship
Fig.1: Dry Density Vs Moisture Content Relationship
Effect of Compaction on Soil Properties
Structure of SoilPermeability ShrinkageSwellingPore Pressure CompressibilityShear Strength
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