use of fly ash for road and embankment construction crri sudhir mathur
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Use of Fly Ash for Road and Embankment Construction CRRI Sudhir MathurTRANSCRIPT
Use of Fly Ash for Road Use of Fly Ash for Road & Embankment & Embankment
Construction Construction
Presentation by
Sudhir MathurHead
Geotechnical Engineering DivisionCentral Road Research Institute, New Delhi
Major Road Construction Major Road Construction ProgrammesProgrammes
• National Highway Development Programme (NHDP)
• Pradhan Mantri Gram Sadak Yojna (PMGSY)
Necessity of alternate Necessity of alternate materialsmaterials
• Large quantities of construction materials required
• Scarcity of good quality aggregates / soil for road construction
• Waste and marginal materials like flyash
• Disposal and environmental problem
Properties of Fly ashProperties of Fly ash
Major constituents - Oxides of silica, aluminum, iron, calcium & magnesium
Favourable properties for embankment & road construction - Pozzolanic nature
- Light weight, Non plastic- High shear strength- Ease of compaction- Self hardening- Amenable to stabilization- High permeability- Faster rate of consolidation
Utilization of Fly ashUtilization of Fly ash
• Construction of embankments / backfills
• Stabilization of subgrade and sub-base
• Construction of semi-rigid / rigidpavements
Engineering Properties of Fly ashEngineering Properties of Fly ashParameter Range Specific Gravity 1.90 – 2.55 Plasticity Non-Plastic Maximum Dry Density (gm/cc) 0.9 – 1.60 Optimum Moisture Content (%) 18-38 Cohesion (kN/m2) Negligible Angle of Internal Friction () 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 Partcle 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
Physical Characteristics for Flyash as Pozzolana
Physical Characteristics for Flyash as Pozzolana
Indian Roads CongressSpecial Publication 58
Guidelines For Use Of Flyash In Road Embankment
Published in 2001
Guidelines for Use of Fly ash in Guidelines for Use of Fly ash in Road EmbankmentsRoad Embankments
These guidelines provide salient details regarding design and construction of road embankments using fly ash
• Site investigations• Characterization of materials• Detailed design• Clearing and grubbing• Stripping and storing top soil• Setting out• Dewatering• Compacting the ground supporting embankment• Handling and transportation of fly ash• Spreading and compaction
Fly Ash for Road Embankment
Earth Cover Earth
Cover
Bottom ash or Pond ash
Typical cross section of fly ash road embankment
FLYASH
FLYASH
FLYASH
Bituminous Top
Granular Layer
SelectedEarth Cover
Shoulder
0.5m minimum
Natural Ground Level
1-3m
Typical cross section of fly ash road embankment
Approach Embankment for Second Approach Embankment for Second Nizamuddin Bridge at DelhiNizamuddin Bridge at Delhi
– Length of embankment - 1.8 km – Height varies from 6 to 9 m– Ash utilized - 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
Design ConsiderationDesign Consideration
The following major factors weighted heavily while designing the fly ash embankment
Adverse site condition – location of site in flood plain area
Low specific gravity of fly ash- may lose strength under submergence
Non availability of specific data and specifications of using fly ash as structural fill
Approach Embankment for Nizamuddin Bridge Approach Embankment for Nizamuddin Bridge
Slope stability analysis of fly ash embankmentSlope stability analysis of fly ash embankment(Different side cover thickness)(Different side cover thickness)
Details Factor of safetyCase I Case II
6 m high embankment, 1 m side cover throughout
1.5 m side cover throughout
2 m side cover upto mid height and remaining portion 1 m cover
2 m side cover throughout
--
1.30
1.42
1.48
1.05
1.20
1.36
1.41
Case I Fly ash saturated upto mid height
Case II Fly ash saturated upto top level
Approach Embankment for Second Approach Embankment for Second Nizamuddin Bridge at DelhiNizamuddin Bridge at Delhi
Spreading of pond ash
Compaction of pond ash
Second Nizamuddin Bridge Approach Embankment
Second Nizamuddin Bridge Approach Embankment
Stone pitching for slope protection
Traffic plying on the embankment
Approach Embankment for Nizamuddin Bridge Approach Embankment for Nizamuddin Bridge
Following instruments installed for monitoring performance of embankment
– Magnetic settlement gauges for settlement
– Pressure cells for base pressure – Pore pressure transducers for pore
water pressure measurement
InstrumentationInstrumentation
Second Nizamuddin Bridge Approach Embankment
Installation of pressure cells
Installation of settlement gauge under progress
Approach Embankment for Nizamuddin Bridge Approach Embankment for Nizamuddin Bridge
– No settlement of the embankment structure (fly ash fill)
– No pressure variation with in embankment body
– No change in saturation level of fly ash fill
Inferences from instrumentation dataInferences from instrumentation data
TechnoTechno--Economic AdvantagesEconomic Advantages
• Direct saving of about Rs.One Crore in second Nizamuddin Bridge project for PWD
• Additional savings to Vidyut Board, saving of precious top soil
• In road projects savings to the extent of 15-20 per cent can be achieved
• Savings depend on cost of transportation of fly ash
1.6 m
.3 m (drain) ((drain)
2.3 m
0.15 m, M15 concrete
1 m
0.5 m
2.0
10.2 mPond ash
7.0 m1.2 m
Existing Embankment
4.0 m
Filter 0.2 m, thickStone pitching, 0.3 m thick
Ground level
6 m
H.F.L
Foot path
0.6 m x 0.8 m parapet wall
1.5 m
1.5 m
Existing carriage way
Stone pitching to be removed
Weep holes at 1-2m c/c
Intermediate soil layers (0.2 m compacted thickness)
Parameter Pond ash Earth cover Sub soil
bulk 1.56 kg/cm2 2.0 kg/cm2 1.8 kg/cm2
c 0 0.15 kg/cm2 0
33o 28o 30o
Sat.condition Factor of safety
With Earthquake Without Earthquake
At H.F.L 1.06 1.7
Sudden drawdown
1.2 1.35
Fly ash Embankment from G.T Road to Kajouri chowk, Delhi
Filter material by the side of toe wall
Stone pitching on filter material
Drainage system in the embankment
USE OF POND ASH FOR ROAD USE OF POND ASH FOR ROAD EMBANKMENT EMBANKMENT
(Four-laning work on NH-6, Dankuni to Kolaghat, Km 17 to 72, West Bengal)
• National Highways Authority of India – Client
• M/s ICT, India and SNC-LALALIN,Canada –Consultant
• M/s Road builders (M) Shd.Bhd, Malaysia - Contractor
AGENCIES INVOLVEDAGENCIES INVOLVED
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
• Length of road - 60 km
• Height of embankment - 2 to 4 m
• Water logged conditions
• Soft sub-soil conditions
TYPICAL ROAD FEATURES/CONDITIONS TYPICAL ROAD FEATURES/CONDITIONS OF THE PROPOSED ROADOF THE PROPOSED ROAD
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
c
Existing carriageway
Typical CrossTypical Cross--section of Existing section of Existing HighwayHighway
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
EXISTING CONDITION OF ROADEXISTING CONDITION OF ROAD
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
EXISTING CONDITION OF ROAD OTHER EXISTING CONDITION OF ROAD OTHER SIDESIDE
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
PRELIMINARY INVESTIGATION AND PRELIMINARY INVESTIGATION AND ASSESSMENT OF SITE CONDITIONSASSESSMENT OF SITE CONDITIONS
• Medium to High rainfall• Water table is high• Waterlogged conditions
• Subsoil generally weak– Silty clay or clayey soil up to 20 m depth– SPT values in the range of 2 to 5– C = 0.25 kg/cm2, = 0o
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
NEED FOR ALTERNATIVE MATERIALNEED FOR ALTERNATIVE MATERIAL
• Earth proposed in contract document. Earth requirement –approx. 2.0 million cum.
• Haul distance more than 100 km.• High transportation cost• Delays expected in the completion of the
project
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
LABORATORY AND FIELD LABORATORY AND FIELD INVESTIGATIONSINVESTIGATIONS
• Characterisation of soil and fly ash
• Sub-soil investigations
• Stability analysis with soil and fly ash as fill materials
• Evaluation of data to arrive at appropriate methodologies for construction
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
ARRANGEMENT FOR DEWATERING OF ARRANGEMENT FOR DEWATERING OF STAGNANT WATERSTAGNANT WATER
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
CONDITION OF THE GROUND AFTER CONDITION OF THE GROUND AFTER DEWATERINGDEWATERING
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
Soil cover (1.5 m thick)
Sand or bottom ash min. 0.5 m thick
Improved Subgrade of compacted thickness not less than 50 cm
Geotextile
Fly ash in compacted layers of 200 mm thickness
Temporary pond ash bund
Existing embankment
2 m 2 m
Median
21
Proposed berm of pond ash after completion of embankment
Granular sub-base
Min. 0.5 m
PROPOSED ALTERNATIVES FOR PROPOSED ALTERNATIVES FOR CONSTRUCTIONCONSTRUCTION
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
SPREADING OF GEOTEXTILE SPREADING OF GEOTEXTILE OVER SOFT GROUNDOVER SOFT GROUND
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
SPREADING OF GEOTEXTILE SPREADING OF GEOTEXTILE OVER SOFT GROUNDOVER SOFT GROUND
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
SPREADING OF FLY ASH OVER SPREADING OF FLY ASH OVER GEOTEXTILEGEOTEXTILE
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
SPREADING OF FLY ASH OVER SPREADING OF FLY ASH OVER GEOTEXTILEGEOTEXTILE
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
COMPACTION OF FLY ASH OVER COMPACTION OF FLY ASH OVER GEOTEXTILE LAID ON SOFT GEOTEXTILE LAID ON SOFT
GROUND, (WORK ON THIS PROJECT GROUND, (WORK ON THIS PROJECT IS IN PROGRESS)IS IN PROGRESS)
FourFour--laning work on NHlaning work on NH--6, Dankuni to Kolaghat,6, Dankuni to Kolaghat,
Kalindi Road Project
SCPT Test In Progress
General Site Condition
Subsoil Investigation in Progress
Reinforced Fly ash EmbankmentReinforced 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
Okhla Flyover Approach EmbankmentOkhla 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
Facing PanelsFilter Medium Geogrids
Pond Ash Fill
Reinforced Foundation Mattressof Bottom ash
7.8 m
7.8 m to 5.9 m
Okhla Flyover Approach EmbankmentOkhla Flyover Approach Embankment
Okhla Flyover Approach Embankment
Erection of facing panels
Rolling of pond ash
Okhla Flyover Approach Embankment
Support provided to facing panels during construction
Laying of geogrids
Hanuman Setu Flyover Approach EmbankmentHanuman 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
Reinforced Retaining Wall at Sarita Vihar Flyover
Sarita Vihar Flyover Approach Sarita Vihar Flyover Approach EmbankmentEmbankment
– Length of embankment - 90m – Max height - 5.25 m– Embankment opened to traffic in
Feb 2001– Polymeric friction ties used for
reinforcement
Sarita Vihar Flyover Reinforced Approach Embankment
Arrangement of friction ties before laying pond
ash
Laying of friction ties
Sarita Vihar Flyover Reinforced Approach Embankment
Compaction using plate vibrator near the
facing panels
Compaction of pond ash using static and vibratory rollers
Design of Reinforced Flyash Embankment
• Height of Wall – 8m • Reinforcing Material – Geogrid • Back Fill – Soil and Flyash• Design of Wall- BS 8006-1995• Checks made- Internal and External Stability
- F.S. against Sliding- F.S. against overturning- F.S against bearing capacity- F.S. against rupture- F.S. against pullout
No of Layers = 12
0.20.81.422.63.23.8
4.6
5.4
6.2
7
0 2 4 6 8Length of geogrid (m)
Vert
ical
Spa
cing
(m)
No of Layers = 16
0.20.611.41.82.22.633.43.8
4.4
5
5.6
6.2
6.8
7.4
0 2 4 6 8
Length of geogrid (m)
Vert
ical
Spa
cing
(m)
Soil Fly Ash
F.S. Sliding 1.97 2.18
F.S. Overturning 4.10 4.50
Bearing Pressure 259 KN/m2 179 KN/m2
Slope Failure of High Embankment of Noida- Greater Noida Expressway
Salient features of site• Height of embankment
varies from 3m to8m• Approximately 23 km
stretch • Six Lane Carriageway
with Median
• Side shoulders – 1.5mPaved & 1m Unpaved
• Flyash covered with Good Earth
Noida-Greater Noida Expressway
CrossCross--Section Proposed for NOIDASection Proposed for NOIDA--GREATER NOIDA Express HighwayGREATER NOIDA Express Highway
Causes and types of Failure
• Heavy Runoff from six lane carriageway discharged water on side slopes•Sandy Silty soil was used as cover without proper slope protection•Severe Erosion on superelevated sections• Absence of longitudinal kerb channel and chutes allowed water to drain off along slope
Types of Failure
• Failures observed on both sides of slope
•More pronounced on d/s side
•Deep cavities were observed exposing fly ash at many locations
• Undermining caused caving in of road pavement
Causes of Failure
• Heavy flow of water intersected side slopes inspite of grass turfing
•Deep pits in slope to provide foundation for crash barrier and electric poles
•Pits were loosely backfilled
Immediate Preventive Measures
• Prevention of flow of water in side slopes by providing soil filled up bags through out the slope
•Filling of soil in erosion gullies
•Filling of soil filled bags in deep cavities
Long Term Remedial Long Term Remedial MeasuresMeasures
• Compaction of Side Slopes
• Provision of Toe Walls
• Provision of Kerb Channel
• Provision of Chutes
• Provision of drains in Medians
• Provision of Stone Pitching along with Filter (Granular/Geotextile)
Remedial Measures
IRC Guidelines / SpecificationsIRC Guidelines / SpecificationsGuidelines available on pavement construction
IRC 60 ‘Tentative guidelines for use of lime fly ash concrete as pavement base or subbase’
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 subbase’
IRC 88 ‘Recommended practice for lime fly ash stabilised soil as base or subbase in pavement construction’
ConclusionsConclusions• Ideally suited as back fill 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• Use of vibratory rollers is preferred
In road projects savings to the extent of 15-25 per cent can be achieved. Savings depend on cost of transportation of fly ash
Coarse ash is suitable as a fill material, finer part of the ash (fly ash) collected in dry form can be used to replace cement
Fly ash collection and handling techniques need to be improved
Use of ash for all road projects in the vicinity of thermal power plant should be made mandatory
Conservation of conventional construction materials is possible by adopting fly ash for road construction
Thank youThank you