Use of Locally Available Materials and Stabilisation Technique

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Use of Locally Available Materials and
Stabilisation Technique

• Dr. M.S. AMARNATH
• Bangalore University
• Bangalore

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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

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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.

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Methods of Soil Stabilization

• Mechanical Stabilization
• Soil Cement Stabilization
• Soil Lime Stabilization
• Soil Bitumen Stabilization
• Lime Fly ash Stabilization
• Lime Fly ash Bound Macadam.

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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

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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.

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Factors Affecting Mechanical Stabilization

• Mechanical Strength of aggregates
• Gradation
• Properties of the Soil
• Presence of Salts
• Compaction

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• 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

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• 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

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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

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Factors affecting soil cement stabilization

• Soil
• Cement
• Pulverisation and Mixing
• Compaction
• Curing
• Additives

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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 and
durability
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• 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

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• 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

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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

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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

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Soil-Lime is effectively used in Expansive soils
with high plasticity index.
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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

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• 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.

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• 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

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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

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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.

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• 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

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• 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

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Use of Locally Available Materials in Road
Construction
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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

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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

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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

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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

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Industrial wastes

• Thermal Power Stations
• Fly ash
• Bottom ash
• Pond ash
• Steel Plants
• Blast furnace slag
• Granulated blast furnace slag
• Steel slag

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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

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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

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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
  

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Engineering properties of fly ash
Parameter Range
Specific Gravity 1.90 2.55
Plasticity Non plastic
Maximum dry density (gm/cc) 0.9 1.6
Optimum moisture content () 38.0 18.0
Cohesion (kN/m2) Negligible
Angle of internal friction (j) 300 400
Coefficient of consolidation Cv (cm2/sec) 1.75 x 10-5 2.01 x 10-3
Compression index Cc 0.05 0.4
Permeability (cm/sec) 8 x 10-6 7 x 10-4
Particle size distribution ( of materials) Clay size fraction Silt size fraction Sand size fraction Gravel size fraction 1 10 8 85 7 90 0 10
Coefficient of uniformity 3.1 10.7
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Differences between Indian US fly ashes
Property compared Indian fly ash US fly ash
Loss on ignition (Unburnt carbon) Less than 2 per cent 5 to 8 per cent
SO3 content 0.1 to 0.2 per cent 3 to 4 per cent
CaO content 1 to 3 per cent 5 to 8 per cent
Increase in concentration of heavy metals 3 to 4 times in comparison to source coal 10 times or more in comparison to source coal
Rate of leaching Lower Higher
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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

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

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Approach embankment for second Nizamuddin bridge
at Delhi
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Spreading of pond ash
Second Nizamuddin bridge approach embankment
Compaction of pond ash
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Stone pitching for slope protection
Second Nizamuddin bridge approach embankment
Traffic plying on the embankment
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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
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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

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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

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Okhla flyover approach embankment
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Erection of facing panels
Okhla flyover approach embankment
Rolling of pond ash
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Support provided to facing panels during
construction
Okhla flyover approach embankment
Laying of geogrids
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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

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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

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Laying of friction ties
Sarita Vihar flyover reinforced approach
embankment
Arrangement of friction ties before laying pond
ash
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Compaction of pond ash using static and vibratory
rollers
Sarita Vihar flyover reinforced approach
embankment
Compaction using plate vibrator near the facing
panels
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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

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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

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Typical cross section of flexible pavement
conventional section
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Fly ash 6 cement stabilised layer 150 mm
Typical cross section of flexible pavement
using fly ash
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Fly ash admixed PQC 300 mm
DLFC 100 mm
Pond ash 300 mm
Typical cross section of rigid pavement using
fly ash
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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

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Mixing of lime stabilised pond ash
Demonstration road project using fly ash at
Raichur
Compaction of stabilised pond ash using road
roller
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Construction of roller compacted concrete pavement
Demonstration road project using fly ash at
Raichur
View of the demonstration road stretch after
three years
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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 124
• 30 per cent of cement and 20 per cent of sand
  replaced with fly ash in RCCP
• Shoulders 8 cement stabilised fly ash

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Demonstration road project using fly ash near
Dadri (U.P) Typical section
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Demonstration road project using fly ash near
Dadri (U.P)
Stabilised base course
Compaction of RCCP
Mixing laying of RCCP
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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 pavement
  construction

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Guidelines for use of fly ash in road embankments

• Published recently by Indian Roads Congress
  (SP- 582001)
• 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

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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

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Granulated blast furnace slag Contains reactive
silica Suitable for lime / cement stabilisation
Air cooled blast furnace slag Non
reactive Suitable for use as coarse aggregates
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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

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Properties of air cooled slag
Property Durgapur Bhilai Rourkela Delhi Quartzite Specification requirements
Specific gravity 2.78 2.82 2.82 3.33 2.97 2.99 2.67 -
Water absorption () 1.53 1.72 0.58 1.38 0.74 1.29 0.48 2 Max
Los Angeles abrasion value () 18.80 25.00 14.28 34.00 40 Max
Impact value () 15.79 14.80 16.90 24.50 30 Max
Soundness value () 1.66 1.17 0.33 0.17 12 Max
Percentage voids 46.40 43.90 43.10 43.80 -
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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

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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 RD Centre for Iron Steel,
  Ranchi using Slags from Bokaro Plant

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Construction of test track using slag at Orissa
Labour based techniques for construction of
stabilised layer
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Lime stabilisation of iron slags (Orissa)
View of finished surface of road constructed
using slags at Orissa
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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

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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
  unsuitable for use in bituminous pavement

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