Use of Locally Available Materials and Stabilisation Technique

1. Use of Locally Available Materials and Stabilisation Technique Dr. M.S. AMARNATH Bangalore University Bangalore

2. Soil Stabilization • The soil stabilization means the improvement of stability or bearing power of the soil by the use of controlled compaction, proportioning and/or the addition 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. 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. 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. 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. 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. Factors Affecting Mechanical Stabilization • Mechanical Strength of aggregates • Gradation • Properties of the Soil • Presence of Salts • Compaction

8. Mechanical Strength • When the soil is used in small proportion to fill up the voids the crushing strength of aggregates is important • Gradation • A well graded aggregate soil mix results in a mix with high dry density and stability values • Properties of soil • A mix with Plasticity Index, results poor stability under soaking conditions. Hence it is desirable to limit the plasticity index of the soil

9. Presence of Chemicals • Presence of Salts like Sulphates and mica • are undesirable • Presence of Calcium Chloride is Beneficial • Compaction • Effective Compaction is desirable to • produce high density and stability mix

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. Factors affecting soil cement stabilization • Soil • Cement • Pulverisation and Mixing • Compaction • Curing • Additives

12. Soil THE PHYSICAL PROPERTIES • Particle Size Distribution • Clay content • Specific Surface • Liquid limit and Plasticity Index Cement A increase in cement content generally causes increase in strength anddurability

13. Pulverisation and Mixing • Better the Pulverisation and degree of mixing, higher is the strength • Presence of un pulverised dry lumps reduces the strength • Compaction • By increasing the amount of compaction dry density of the mix, strength and durability also increases

14. Curing • Adequate Moisture content is to be retained in • order to accelerate the strength • Additives • There are some additives to improve properties • Lime • Sodium hydroxide • Sodium Carbonate • Calcium Chloride

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. Soil Lime Stabilization • Soil- Lime has been widely used as a • modifier 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. Soil-Lime is effectively used in Expansive soils with high plasticity index.

18. Factors affecting Properties of Soil-Lime • Lime 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. 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. 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 strength • Additives • Sodium metasilicate, Sodium hydroxide and • Sodium Sulphate are also found useful additives

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. 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. 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. Compaction • Effective Compaction results higher • stability and resistance to absorb water • Additives • 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. Use of Locally Available Materials in Road Construction

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. 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. 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. 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. Industrial wastes • Thermal Power Stations * Fly ash * Bottom ash * Pond ash • Steel Plants * Blast furnace slag * Granulated blast furnace slag * Steel slag

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. Utilisation of fly ash • Can be used for construction of • Embankments and backfills • Stabilisation of subgrade and sub-base • Rigid and semi-rigid pavements • Fly ash properties vary widely, to be characterised before use • Major constituents - oxides of silica, aluminum, iron, calcium & magnesium • Environmentally safe material for road construction • Possesses many favourable properties for embankment & road construction

33. Favourable properties of fly ash • Light weight, lesser pressure on sub-soil • High shear strength • Coarser ashes have high CBR value • Pozzolanic nature, additional strength due to self-hardening • Amenable to stabilisation • Ease of compaction • High permeability • Non plastic • Faster rate of consolidation and low compressibility • Can be compacted using vibratory or static roller

34. Engineering properties of fly ash

35. Differences between Indian & US fly ashes

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. Fly ash for road embankment Typical cross section of fly ash road embankment

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. Approach embankment for second Nizamuddin bridge at Delhi

40. Spreading of pond ash Second Nizamuddin bridge approach embankment Compaction of pond ash

41. Stone pitching for slope protection Second Nizamuddin bridge approach embankment Traffic plying on the embankment

42. Utilisation of fly ash Four laning work on NH-6 (Dankuni to Kolaghat) Length of stretch – 54 km Height of embankment – 3 to 4 m Fly ash utilisation – 2 Million cubic metres Water logged area (soft ground conditions) Compaction of fly ash over layer of geotextile

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. 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. Okhla flyover approach embankment Filter medium Geogrids Facing panels 7.8 to 5.9 m Reinforced foundation mattress of bottom ash

46. Erection of facing panels Okhla flyover approach embankment Rolling of pond ash

47. Support provided to facing panels during construction Okhla flyover approach embankment Laying of geogrids

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. 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. Laying of friction ties Sarita Vihar flyover reinforced approach embankment Arrangement of friction ties before laying pond ash