Soil stab use of-new.ppt dr msa edusat.ppt rev 1


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Soil stabilization methods

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  • Construction of Salarpur-Dadupur Rural Link Road Using Fly ash This project was taken up as part of an initiative supported by Canadian International Development Agency (CIDA) on thermal power plant ash utilisation. In this demonstration project it was decided to use bottom ash as a substitute for soil in the embankment. Bottom ash was covered with 30 cm thick soil layer to protect it from erosion. 8 per cent cement stabilised fly ash was provided as base course. Roller Compacted Concrete Pavement (RCCP) was adopted as wearing course. The mix proportion of RCCP adopted was 1:2:4. In RCCP, 30 per cent of cement and 20 per cent of fine aggregate (sand) was replaced with dry fly ash.
  • Normally the thickness of RCC pavement required for such rural roads would be about 23 cm. However based on earlier experience and due to limited finances available, it was decided to provide only 10 cm compacted thickness of RCC wearing course. Keeping in view the fact that the link road is located in a remote area and only light traffic is expected to ply on the road (less than 15 CVD), the pavement is expected to provide satisfactory service. Shoulders of 0.5 m width were provided on either side of the pavement. The shoulders were constructed using 8 % cement stabilised fly ash for a compacted thickness of 0.1 m.
  • The construction work of the demonstration stretch was taken up under the supervision of CRRI. Spreading of the embankment fill, stabilised mix and laying of RCC were carried out manually. Compaction was carried out using 8 ton static road roller. Concrete and stabilised fly ash mixing was carried out using diesel operated concrete mixer. The construction work was taken up in March 2002 and completed in about 60 days.
  • Soil stab use of-new.ppt dr msa edusat.ppt rev 1

    1. 1. Use of Locally Available Materials and Stabilisation Technique Dr. M.S. AMARNATH Bangalore University Bangalore
    2. 2. Soil StabilizationThe soil stabilization means the improvement ofstability or bearing power of the soil by the use ofcontrolled compaction, proportioning and/or theaddition of suitable admixture or stabilizers.Basic Principles of Soil Stabilization….• Evaluating the properties of given soil• Deciding the lacking property of soil and choose effective and economical method of soil stabilization• Designing the Stabilized soil mix for intended stability and durability values
    3. 3. Need for Soil Stabilization Limited Financial Resources to Provide a complete network Road System to build in conventional method Effective utilization of locally available soils and other suitable stabilizing agents. Encouraging the use of Industrial Wastages in building low cost construction of roads.
    4. 4. Methods of Soil Stabilization• Mechanical Stabilization• Soil Cement Stabilization• Soil Lime Stabilization• Soil Bitumen Stabilization• Lime Fly ash Stabilization• Lime Fly ash Bound Macadam.
    5. 5. Mechanical Stabilization• This method is suitable for low volume roads i.e. Village roads in low rainfall areas.• This method involves the correctly proportioning of aggregates and soil, adequately compacted to get mechanically stable layer• The Basic Principles of Mechanical Stabilization are Correct Proportioning and Effective Compaction
    6. 6. Desirable Properties of Soil- Aggregate Mix • Adequate Strength • Incompressibility • Less Changes in Volume • Stability with Variation in water content • Good drainage, less frost Susceptibility • Ease of Compaction.
    7. 7. Factors Affecting Mechanical Stabilization Mechanical Strength of aggregates Gradation Properties of the Soil Presence of Salts Compaction
    8. 8. Mechanical Strength• When the soil is used in small proportion to fillup the voids the crushing strength of aggregatesis importantGradation• A well graded aggregate soil mix results in amix with high dry density and stability valuesProperties of soil• A mix with Plasticity Index, results poor stabilityunder soaking conditions. Hence it is desirable tolimit the plasticity index of the soil
    9. 9. Presence of Chemicals• Presence of Salts like Sulphates and mica are undesirable• Presence of Calcium Chloride is BeneficialCompaction• Effective Compaction is desirable to produce high density and stability mix
    10. 10. Soil Cement Stabilization• Soil Cement is an intimate mix of soil, cement and water, compacted to form a strong base course• Cement treated or cement modified soil refers to the compacted mix when cement is used in small proportions to impart some strength• Soil Cement can be used as a sub-base or base course for all types of Pavements
    11. 11. Factors affecting soil cement stabilization • Soil • Cement • Pulverisation and Mixing • Compaction • Curing • Additives
    12. 12. Soil THE PHYSICAL PROPERTIES • Particle Size Distribution • Clay content • Specific Surface • Liquid limit and Plasticity IndexCement A increase in cement content generallycauses increase in strength and durability
    13. 13. Pulverisation and Mixing• Better the Pulverisation and degree of mixing, higher is the strength• Presence of un pulverised dry lumps reduces the strengthCompaction• By increasing the amount of compaction dry density of the mix, strength and durability also increases
    14. 14. Curing Adequate Moisture content is to be retained in order to accelerate the strengthAdditives There are some additives to improve properties• Lime• Sodium hydroxide• Sodium Carbonate• Calcium Chloride
    15. 15. Design of Soil –Cement Mix• Soil – Cement specimens are prepared with various cement contents in constant volumes moulds• The compressive strength of these specimens tested after 7 days of curing• A graph is plotted Cement content Vs compressive strength• The Cement Content Corresponding to a strength of 17.5 kg/cm2 is taken as design cement content
    16. 16. Soil Lime Stabilization• Soil- Lime has been widely used as amodifier or a binder• Soil-Lime is used as modifier in high plasticity soils• Soil Lime also imparts some binding action even in granular soils
    17. 17. Soil-Lime is effectively used in Expansivesoils with high plasticity index.
    18. 18. Factors affecting Properties of Soil-LimeLime Content• Generally increase in lime content causes slight change in liquid limit and considerable increase in Plasticity index• The rate of increase is first rapid and then decreases beyond a certain limit• The point is often termed as lime fixation point This is considered as design lime content
    19. 19. Type of Lime After long curing periods all types of limes produce same effects. However quick lime has been found more effective than hydrated lime Calcium Carbonate must be heated at higher temperature to form Quick lime calcium oxide( CaO) Calcium oxide must be slaked ( by the addition of water) to form Hydrated lime Compaction Compaction is done at OMC and maximum dry density.
    20. 20. Curing• The strength of soil-lime increases with curing period upto several years. The rate of increase is rapid during initial period• The humidity of the surroundings also affects the strengthAdditives• Sodium metasilicate, Sodium hydroxide and Sodium Sulphate are also found useful additives
    21. 21. Soil- Bituminous Stabilization• The Basic Principles of this stabilization are Water Proofing and Binding• By Water Proofing inherent strength and other properties could be retained• Most Commonly used materials are Cutback and Emulsion• Bitumen Stabilized layer may be used as Sub-base or base course for all the roads
    22. 22. Factors affecting properties of soil-bitumen Soil • The particle size, shape and gradation of the soil influence the properties of the soil-bitumen mix. Types of Bitumen • Cutbacks of higher grade should be preferred • Emulsions generally gives slightly inferior results than Cutback.
    23. 23. Amount of Mixing• Increasing proportion of bitumen causes a decrease in dry density but increases the stability after a certain bitumen content• The optimum bitumen content for maximum stability generally ranges from 4 to 6%Mixing• Improved type of mixing with low mixing period may be preferred
    24. 24. Compaction• Effective Compaction results higher stability and resistance to absorb waterAdditives• Anti stripping and reactive chemical additives have been tried to improve the properties of the mixes• Portland cement can also be used along with the soil bitumen
    25. 25. Use of Locally AvailableMaterials in Road Construction
    26. 26. Necessity Scarcity of good quality aggregates / soil for road construction Production and accumulation of different waste materials Disposal and environmental problem Economical and gainful utilisation
    27. 27. Limitations of Using Waste Materials Quality of waste is not controlled by their manufacturers Characteristics of by-products vary in a wide range Road construction practice is accustomed to traditional materials of steady quality Specifications of layers compaction of traditional materials are not suitable for waste materials
    28. 28. General Criteria for Use of Waste Materials Amount of yearly produced waste material should reach a certain lower limit The hauling distance should be acceptable The material should not have a poissonous effect The material should be insoluble in water The utilisation should not have a pollutional effect to the environment
    29. 29. Special Requirement for Using Waste Materials Free from organic matter Should not swell or decay as influenced by water Should not be soluble in water Particles should be moderately porous
    30. 30. Industrial wastes Thermal Power Stations * Fly ash * Bottom ash * Pond ash Steel Plants * Blast furnace slag * Granulated blast furnace slag * Steel slag
    31. 31. Utilisation of fly ash Thermal power - Major role in power generation Indian scenario - Use of coal with high ash content - Negligible utilisation of ash produced Bulk utilisation - Civil engineering applications like construction of roads & embankments
    32. 32. Utilisation of fly ashCan be used for construction of Embankments and backfills Stabilisation of subgrade and sub-base Rigid and semi-rigid pavementsFly ash properties vary widely, to becharacterised before useMajor constituents - oxides of silica,aluminum, iron, calcium & magnesiumEnvironmentally safe material for roadconstructionPossesses many favourable propertiesfor embankment & road construction
    33. 33. Favourable properties of fly ashLight weight, lesser pressure on sub-soilHigh shear strengthCoarser ashes have high CBR valuePozzolanic nature, additional strength due toself-hardeningAmenable to stabilisationEase of compactionHigh permeabilityNon plasticFaster rate of consolidation and lowcompressibilityCan be compacted using vibratory or static roller
    34. 34. Engineering properties of fly ashParameter RangeSpecific Gravity 1.90 – 2.55Plasticity Non plasticMaximum dry density (gm/cc) 0.9 – 1.6Optimum moisture content (%) 38.0 – 18.0Cohesion (kN/m 2 ) NegligibleAngle of internal friction (j) 30 0 – 40 0Coefficient of consolidation C v (cm 2 /sec) 1.75 x 10 -5 – 2.01 x 10 -3Compression index C c 0.05 – 0.4Permeability (cm/sec) 8 x 10 -6 – 7 x 10 -4Particle size distribution (% of materials) Clay size fraction 1 – 10 Silt size fraction 8 – 85 Sand size fraction 7 – 90 Gravel size fraction 0 – 10Coefficient of uniformity 3.1 – 10.7
    35. 35. Differences between Indian & US fly ashesProperty compared Indian fly ash US fly ashLoss on ignition Less than 2 per 5 to 8 per cent (Unburnt carbon) centSO 3 content 0.1 to 0.2 per 3 to 4 per cent centCaO content 1 to 3 per cent 5 to 8 per centIncrease in 3 to 4 times in 10 times or more inconcentration of comparison to comparison to sourceheavy metals source coal coalRate of leaching Lower Higher
    36. 36. Fly ash for road embankment Ideally suited as backfill material for urban/ industrial areas and areas with weak sub soils Higher shear strength leads to greater stability Design is similar to earth embankments Intermediate soil layers for ease of construction and to provide confinement Side slope erosion needs to be controlled by providing soil cover Can be compacted under inclement weather conditions 15 to 20 per cent savings in construction cost depending on lead distance
    37. 37. Fly ash for road embankmentTypical cross section of fly ash road embankment
    38. 38. Approach embankment for second Nizamuddin bridge at Delhi– Length of embankment - 1.8 km– Height varies from 6 to 9 m– Ash utilised - 1,50,000 cubic metre– Embankment opened to traffic in 1998– Instrumentation installed in the embankment showed very good performance– Approximate savings due to usage of fly ash is about Rs.1.00 Crore
    39. 39. Approach embankment for second Nizamuddin bridge at Delhi
    40. 40. Spreading of pond ashSecond Nizamuddin bridge approach embankmentCompaction of pond ash
    41. 41. Stone pitching for slope protectionSecond Nizamuddin bridge approach embankmentTraffic plying on the embankment
    42. 42. Utilisation of fly ashFour laning work on NH-6 (Dankuni to Kolaghat) Length of stretch – 54 km Height of embankment – 3 to 4m Fly ash utilisation – 2 Million cubic metres Water logged area(soft ground conditions) Compaction of fly ash over layer of geotextile
    43. 43. Reinforced fly ash embankment Fly ash - better backfill material for reinforced embankments Polymeric reinforcing materials – Geogrids, friction ties, geotextiles Construction sequence – similar to reinforced earth structures
    44. 44. Okhla flyover approach embankment– First geogrid reinforced fly ash approach embankment constructed in the country– Length of embankment – 59 m– Height varied from 5.9 to 7.8 m– Ash utilised – 2,700 cubic metre– Opened to traffic in 1996– Performance has been very good
    45. 45. Okhla flyover approach embankment Filter Facing medium Geogrids panels 7.8 to 5.9 m Reinforced foundation mattress of bottom ash
    46. 46. Erection of facing panels Okhla flyover approach embankmentRolling of pond ash
    47. 47. Support provided to facing panels during construction Okhla flyover approach embankmentLaying of geogrids
    48. 48. Hanuman Setu flyover approach embankment – Geogrid reinforced fly ash approach embankment – Length of embankment – 138.4 m – Height varied from 3.42 m to 1.0 m – Opened to traffic in 1997
    49. 49. Sarita Vihar flyover approach embankment – Length of embankment – 90 m – Maximum height – 5.25 m – Embankment opened to traffic in Feb 2001 – Polymeric friction ties used for reinforcement
    50. 50. Laying of friction tiesSarita Vihar flyover reinforced approach embankment Arrangement of friction ties before laying pond ash
    51. 51. Compaction of pond ash using static and vibratory rollersSarita Vihar flyover reinforced approach embankmentCompaction usingplate vibrator near the facing panels
    52. 52. Fly ash for road construction Stabilised soil subgrade & sub- base/base courses – Mixing with soil reduces plasticity characteristics of subgrade – Addition of small percentage of lime or cement greatly improves strength – Leaching of lime is inhibited and durability improves due to addition of fly ash – Pond ash & bottom ash can also be stabilised – Lime-fly ash mixture is better alternative to moorum for construction of WBM / WMM
    53. 53. Fly ash for road construction Construction of semi-rigid/ rigid pavements – Lime-fly ash concrete – Dry lean cement fly ash concrete – Roller compacted concrete – Fly ash admixed concrete pavements – Lime-fly ash bound macadam – Precast block paving – High performance concrete
    54. 54. Bituminous concrete 40 mm 100 mm DBM BM 75 mm WBM Gr III/WMM 75 mm WBM Gr II/WMM 150 mm GSB 350 mm Typical cross section of flexiblepavement – conventional section
    55. 55. Bituminous concrete 40 mm DBM 100 mm BM 75 mm WBM Gr III/WMM 75 mm Fly ash + 6% cement stabilised layer 150 mm Pond ash 350 mmTypical cross section of flexible pavement – using fly ash
    56. 56. Fly ash admixed PQC 300 mm DLFC 100 mm Pond ash 300 mmTypical cross section of rigid pavement – using fly ash
    57. 57. Demonstration road project at Raichur Total length of the road – 1 km Five sections of 200 m each with different pavement sections Pond ash has been used for replacing moorum in sub-base course Stabilised pond ash used for replacing part of WBM layer One rigid pavement section using DLFC and RCCP technology was laid Performance of all the specifications is good
    58. 58. Mixing of lime stabilised pond ashDemonstration road project using fly ash at Raichur Compaction of stabilised pond ash using road roller
    59. 59. Construction of roller compacted concrete pavementDemonstration road project using fly ash at Raichur View of the demonstration roadstretch after three years
    60. 60. Demonstration road project using fly ash near Dadri (U.P)  A rural road near Dadri in District Gautam Budh Nagar, Uttar Pradesh was selected  Total length of road – 1.4 km  Bottom ash used as embankment fill  Base course constructed using fly ash stabilised with 8% cement  RCCP Wearing course – 10 cm thickness  RCCP Mix proportion – 1:2:4  30 per cent of cement and 20 per cent of sand replaced with fly ash in RCCP  Shoulders – 8% cement stabilised fly ash
    61. 61. Demonstration road project using fly ash near Dadri (U.P) – Typical section RCCP wearing course - 0.1 m Stabilised fly ash Stabilised fly ash base - 0.1 m Shoulder Soil cover Bottom ash
    62. 62. Demonstration road project using fly ash near Dadri (U.P)Stabilised base course Mixing & laying of RCCP Compaction of RCCP
    63. 63. IRC Guidelines / Specifications Guidelines available on pavement construction  IRC 60 ‘Tentative guidelines for use of lime fly ash concrete as pavement base or sub- base’  IRC 68 ‘Tentative guidelines on cement fly ash concrete for rigid pavement construction’  IRC 74 ‘Tentative guidelines for lean cement concrete and lean cement fly ash concrete as a pavement base or sub-base’  IRC 88 ‘Recommended practice for lime fly ash stabilised soil as base or sub-base in
    64. 64. Guidelines for use of fly ash in road embankments Published recently by Indian Roads Congress (SP- 58:2001) Includes design aspects also Handling and construction – Loose layer thickness of 400 mm can be adopted if vibratory rollers are used – Moisture content - OMC + 2 per cent – Use of vibratory rollers advocated – Minimum dry density to be achieved - 95 per cent of modified Proctor density – Ash layer and side soil cover to be constructed simultaneously
    65. 65. Utilisation of steel slags Total production of slag from steel industries is about 8.0 million tonnes Types of slags – Blast furnace slag  Granulated blast furnace slag (GBFS)  Air cooled slag – Steel slag
    66. 66. Granulated blast furnace slag Contains reactive silica Suitable for lime / cement stabilisationAir cooled blast furnace slag Non – reactive Suitable for use as coarse
    67. 67. CRRI work on utilisation of steel slags Characterisation of slags produced at different steel plants Laboratory studies on Lime-GBFS mixes Semi-field studies on Lime-GBFS concrete Test track studies on usage of slags in road works
    68. 68. Properties of air cooled slagProperty Durgapur Bhilai Rourkela Delhi Specification Quartzite requirementsSpecific 2.78 – 2.82 – 2.97 – 2.67 -gravity 2.82 3.33 2.99Water 1.53 – 0.58 – 0.74 – 0.48 2% Maxabsorption 1.72 1.38 1.29(%)Los 18.80 25.00 14.28 34.00 40% MaxAngelesabrasionvalue (%)Impact 15.79 14.80 16.90 24.50 30% Maxvalue (%)Soundness 1.66 1.17 0.33 0.17 12% Maxvalue (%)Percentag 46.40 43.90 43.10 43.80 -e voids
    69. 69. Steel slags Obtained as a waste product during production of steel Particle size varies from 80 mm to 300 microns Compared to blast furnace slag, steel slag contains lower amount of silica, higher amounts of iron oxide and calcium oxide Due to presence of free lime, steel slag should be weathered before using it in construction
    70. 70. Road projects executed under CRRI guidance using slags Plant roads at Visakhapatnam Test tracks in collaboration with AP PWD using slags from Visakhapatnam Steel Plant Test tracks in collaboration with Orissa PWD using slags from Rourkella Plant Test tracks at R&D Centre for Iron & Steel, Ranchi using Slags from Bokaro Plant
    71. 71. Construction of test track using slag at Orissa Labour based techniques forconstruction ofstabilised layer
    72. 72. Lime stabilisation of iron slags (Orissa)View of finished surface of road constructed using slags at Orissa
    73. 73. Processed municipal wastes  Processed municipal wastes utilised for construction of test track on village road near Delhi  Stabilised municipal waste used for construction of sub-base layer  Performance of stretch is good
    74. 74. Kimberlite tailings Kimberlite tailings are waste produced from diamond mining Can be used in base or sub-base course by adopting mechanical or cement stabilisation High value of water absorption makes them
    75. 75. THANK YOU