Slide 1: VTU _ Edusat Program 1 2011-10-16 Basics of Soil Compaction Methods & equipment K.Ramanath General Manager & Dean RASTA Road Machinery Business Line Volvo India Private Limited Soil Compaction: VTU _ Edusat Program 2 2011-10-16 Soil Compaction Cost of earth work – 30% Cost of road project Increase in heavy axle load application Well compacted sub-grade results in economy of pavement thickness Proper compaction has great economic implications Slide 3: VTU _ Edusat Program 3 2011-10-16 Road - cross section 40 mm 80 mm 80 mm 300 mm 300 mm 150 mm 150 mm 200 mm 200 mm 200 mm Asphalt concrete / wearing course DBM } Aggregate 67%,stone dust 24% DBM } Sand 9% Bitumen 5% WMM / WBM WMM / WBM GSB } GSB } Aggregate up to 80 mm Soil } } Soil } Muram } Soil } 10% Road thickness comprises of asphalt work - 65% of total value Flexible pavement Objectives Of Soil Compaction: VTU _ Edusat Program 4 2011-10-16 Objectives Of Soil Compaction Increase in strength Reduction in compressibility Reduction in tendency for subsequent changes in moisture content Reduction in erodability Factors Influencing Compaction: VTU _ Edusat Program 5 2011-10-16 Factors Influencing Compaction Type of soil Moisture content Compactive effort - Energy applied per unit weight of soil - Weight of rammer, height of fall, number of blows - Weight of roller, number of passes Thickness of lift and type of compacting equipment (for field compaction) Moisture Content : VTU _ Edusat Program 6 2011-10-16 Moisture Content Water acts as a lubricant Too much takes up space does not allow bonding Too little same compactive effort, lower compaction OMC of fine grain soils is higher than coarse grain soils OMC - The moisture content of the soil at which maximum density can be achieved for a given amount of compactive effort Slide 7: VTU _ Edusat Program 7 2011-10-16 Moisture content - % by dry weight Dry Density Max Dry Density Optimum Moisture content Laboratory Compaction Tests: VTU _ Edusat Program 8 2011-10-16 Laboratory Compaction Tests Dynamic Compaction IS light compaction / standard proctor test IS heavy compaction/ modified proctor test Static Compaction Kneading Compaction Vibratory compaction usually static or dynamic compaction is adopted Comparison Of Compaction Tests: VTU _ Edusat Program 9 2011-10-16 Comparison Of Compaction Tests Standard Proctor Test Modified Proctor Test Soil passing 20 mm / 37.5 mm IS sieve Soil passing 20 mm / 37.5 mm IS sieve Soil compacted in 3 layers , 25 blows / 55 blows Soil compacted in 5 layers , 25 blows / 55 blows Soil compaction by 2.6 kg hammer, 31 cm is height of fall Soil compaction by 4.89 kg hammer, 45 cm is height of fall Adopted for rural roads specifications Adopted for MORTH specifications Used for Internal roads in urban areas and village roads Used for NH, SH, MDR and arterial roads in urban area Moisture-density Relationship For Different Types Of Soils: VTU _ Edusat Program 10 2011-10-16 Moisture-density Relationship For Different Types Of Soils Field Control Of Compaction: VTU _ Edusat Program 11 2011-10-16 Field Control Of Compaction Measurement of dry density Core cutter method (IS: 2720 (Part 29) - 1975) Sand replacement method (IS: 2720 (Part 28) - 1974) Nuclear density & moisture gauge (ASTM D- 2922) Slide 12: VTU _ Edusat Program 12 2011-10-16 Sand Replacement Method Nuclear Test: VTU _ Edusat Program 13 2011-10-16 Nuclear Test If calibrated Field Control Of Compaction Contd…: VTU _ Edusat Program 14 2011-10-16 Field Control Of Compaction Contd… Measurement of moisture content Oven Dry Method Sand bath drying method Infrared torsion balance method Speedy moisture meter (IS 2720 (Part 2 - 1973) Slide 15: VTU _ Edusat Program 15 2011-10-16 Rapid Moisture Meter Method Infra Red Torsion Moisture Balance Meter Soil Compaction: VTU _ Edusat Program 16 2011-10-16 Soil Compaction Soil Compaction is the process whereby soil particles are constrained to pack more closely through a reduction in air voids by mechanical means What is Compaction?: VTU _ Edusat Program 17 2011-10-16 What is Compaction? The act of artificially densifying or increasing the unit weight of soil by application of external forces Reducing the voids or pore spaces to a minimum Increasing the solid particle content to a maximum. Slide 18: VTU _ Edusat Program 18 2011-10-16 Compactive Force Water Air Details of Compactive Effort ( Compaction methods ): VTU _ Edusat Program 19 2011-10-16 Details of Compactive Effort ( Compaction methods ) Static Pressure - weight of the machine - Mass transmitted onto the ground. Impact - blows like that of a hammer Vibration - energy resonates the material into a state of equilibrium Manipulation - mends, shears and kneads Slide 20: VTU _ Edusat Program 20 2011-10-16 Slide 21: VTU _ Edusat Program 21 2011-10-16 Static Pressure Compaction in Road Building is not just applying pressure Compactive Effort: Static: VTU _ Edusat Program 22 2011-10-16 Compactive Effort: Static Weight Three Wheel Static Roller Slide 23: VTU _ Edusat Program 23 2011-10-16 Compaction Effect of 8 Ton Static roller RH Rear Drum LH Rear Drum Static Load 2510 Kgs Static Load 2510 Kgs Static Load 2980 Kgs Front Drum Linear applied load - 47.24 Linear applied load - 47.24 Linear applied load - 29.33 508 mm 508 mm 1016 mm After the first pass 38% Lower density on Front drum Higher density on Rear drum. Uneven mat finish. Slide 24: VTU _ Edusat Program 24 2011-10-16 Total applied force on rear drum = 4950 kgs ( Linear applied load = 41.25 ) Total applied force on Front drum = 4950 kgs ( Linear applied load = 41.25 ) Equal density over full roller width. Even mat surface after first pass Rear Drum Front Drum Tandem Roller - Compaction effect Drum width - 1200 mm 1200 mm Compacted width Slide 25: VTU _ Edusat Program 25 2011-10-16 Two Wheel Static roller Compaction Effect - Impacts: VTU _ Edusat Program 26 2011-10-16 Compaction Effect - Impacts Achieve compaction - through a series of blows Compaction Effort: Vibration: VTU _ Edusat Program 27 2011-10-16 Compaction Effort: Vibration More effective in overcoming internal friction and cohesion Higher in-place density Proven the most cost effective Slide 28: VTU _ Edusat Program 28 2011-10-16 AMPLITUDE 1.7 mm Vertical Distance of Drum Travel Slide 29: VTU _ Edusat Program 29 2011-10-16 Frequency ROLLER DRUM Defined: Number of complete cycles, (speed) of the rotating device, (weight) measured in vibrations per minute (vpm). IMPACT SPACING ( 1 Impact every 20 - 25 mm of travel ) LOW HIGH Impact Spacing Vibrations: VTU _ Edusat Program 30 2011-10-16 Vibrations Compaction occurs from the bottom to the top of the surface. Compactive Effort: Vibration & Impact: VTU _ Edusat Program 31 2011-10-16 Compactive Effort: Vibration & Impact Weight Material Natural Frequency: VTU _ Edusat Program 32 2011-10-16 Material Natural Frequency Soil type Graded sand Graded sand, wet Coastal sand, dry Clay Clay, dry, mixed w/gravel Sandy gravel Firm silt Loose silt Frequency 1980 VPM (33hz) 1440 VPM (24hz) 1320 VPM (22hz) 1200 VPM (20hz) 1110 VPM (18.5 hz) 1500-1740 VPM (25-29hz) 1500-1740 VPM (25-29hz) 1260-1980 VPM (21-33hz) Compactive Effort: Vibration & Manipulation: VTU _ Edusat Program 33 2011-10-16 Compactive Effort: Vibration & Manipulation Slide 34: VTU _ Edusat Program 34 2011-10-16 Pad foot Soil Compactor Slide 35: VTU _ Edusat Program 35 2011-10-16 References 1.IRC Special Report “ State of Art : Compaction of Earthwork and Subgrades”HRB , 1999 2.HMSO publication, Soil Mechanics for Road Engineers 3.Specifications for Road and Bridge Works, IV Edition, MoRTH, IRC Publication Thank you for your attention Questions ? ? ?: VTU _ Edusat Program 36 2011-10-16 Thank you for your attention Questions ? ? ?