methods of soil and base stabilization

8/12/2019 Methods of Soil and Base Stabilization

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SOIL,SUBBASE,BASE

STABILIZATION METHODS

AND DESIGN OF FLEXIBLEPAVEMENTS

DR SUNIL BOSE

FORMER , HEAD FLEXIBLE PAVEMENTS DIVISION,

CENTRAL ROAD RESEARCH INSTITUTE

NEW DELHI([email protected], +919810376409)

&

BRIG Y.S. SIROHI

M/S ALCHEMIST TOUCHNOLOGY LTD

mailto:[email protected]

mailto:[email protected]



WHY SHIFT TO STABILIZATION

Conventional construction material likeaggregates is becoming progressively scarce on

account of environmental concerns as well as

legal restrictions on quarrying while theconstruction activity has expanded phenomenally.

This has shifted focus from large scale use of

conventional aggregates to use of local, recycled

and engineered marginal aggregates in

construction.



SOIL STABILIZATION

THE TERM SOIL STABILIZATION ITSELF IMPLIES

THAT THE SOIL IS UNSTABLE.

IMPLYING THAT IT IS UNSUITABLE FOR TAKING

THE LOAD, FAILS DUE TO SHEAR.

SHOWS EXCESSIVE SETTLEMENT CAN BECONSIDERED AS EXCESSIVE SETTLEMENT



NECESSITY OF SOIL STABILIZATION



DIFFERENT METHODS OF SOIL

STABILIZATION



MECHANICAL STABILIZATION

• Mechanical soil stabilization meansstabilization without adding and chemical

or admixtures.

• It involves addition or removal of soil

component

• Index properties of soil , gap graded soilsare poor bases for compaction



ADVANTAGES OF MECHANICAL

STABILIZATION1) ECONOMICAL2) SIMPLE TO CARRY OUT

3) RAPID, CONSTRUCTION CAN BE IMMEDIATELY

STARTED

DISADVANTAGES OF MECHANICAL

STABILIZATION

1) EFFECTIVE ONLY UPTO A CERTAIN EXTENT

2) NOT SUITABLE FOR ALL SOIL TYPES

3) REQUIRES SPECIAL EQUIPMENT



SOIL – LIME STABILIZATION• THIS TYPE OF STABILIZATION IS SPECIALLY

EFFECTIVE IN CASE OF PLASTIC CLAY

• SLAKED LIME IS FOUND TO BE VERY EFFECTIVE IN

SUCH SOILS

• THIS METHOD IS GENERALLY USED FOR BASESAND SUBGRADES

• LIME IS EITHER USED ALONE OR IN COMBINATION

WITH FLYASH OR CEMENT

• THE PERCENTAGE OF LIME REQUIRED FOR

COARSE GRAINED SOILS IS 2% TO 8% & 5%

TO 10% FOR PLASTIC SOILS



ADVANTAGES OF LIME STABILIZATION

1) CHEAP2) EASY AVAILABILITY OF LIME

3) EXPERT SUPERVISION IS NOT NEEDED

DISADVANTAGES OF LIMESTABILIZATION

1) NO DRASTIC ALTERATIONS IN PROPERTIES2) SUITABLE ONLY FOR PLASTIC CLAYS



CEMENT STABILIZATION:

• THE SOIL STABILIZATION WITH CEMENT ISKNOWN AS SOIL STABILIZATION

• THE CEMENT ACTION IS THE RESULT OF

CHEMICAL WITH SILICON PRESENT IN SOIL

PRESENT IN SOIL DURING THE PROCESS OF

HYDRATION. THIS HAPPENS IN NON-COHESIVE

AND COARSE GRAINED SOIL

• VERY FEW PARTICLES FOR CEMENT BONDING IN

CASE OF FINE GRAINED COHESIVE SOIL



ADVANTAGES OF CEMENT

STABILIZATION1) LARGE INCREASE IN STRENGTH

2) VERY USEFUL FOR LOOSE SOIL AND NON-

COHESIVE SOIL

3) PERMANENT SOLUTION

DISADVANTAGES OF CEMENT

STABILIZATION1)COSTLY

2)COMPLICATED PROCEDURE3)NOT USEFUL FOR CLAYS, ORGANIC SOILS AND

EXPANSIVE SOILS

4)SHRINKAGE CRACKING



CLASSIFICATION OF BITUMEN

STABILIZATION



ADVANTAGES OF BITUMEN

STABILIZATION

1) DURABLE FOR A YEARS2) CHEAPER THAN SOIL CEMENT

3) VERY USEFUL FOR ROAD, SUBGRADES AND

WATER PROOF STRUCTURES

DISADVANTAGES OF BITUMEN

STABILIZATION

1) EFFECTIVE FOR ONLY SOME SOIL TYPES2) NOT USEFUL FOR FOUNDATION

3) WATER PROOFING RATHER THAN STRENGTH

ENHANCEMENT IS ACHIEVED



FLYASH STABILIZATION :• FLYASH IS WATER MATERIAL FORMED DUE OF

MINERAL COAL

• POSSES A DIFFICULTY FOR DISPOSAL

• WHEN USED IN SOIL STABILIZATION ITS ACTION ISTWOFOLD:

1) IT FORMS FILLER OR POZOLANA MATERIAL

2) IT HYDRATES FORMING CEMENT LIKE GEL

• FLYASH BY ITSELF IS RARELY USED IN SOILSTABILIZATION



ADVANTAGES OF FLYASH STABILIZATION

1) ECOFRIENDLY AS IT HELPS IN RECYCLING

OF FLYASH

2) SIMPLE

3) CHEAP

4) RAPID

DISADVANTAGES OF FLYASH

STABILIZATION

1)CEMENT BE USED AS STAND ALONE METHOD

2) ENHANCEMENT IS NOT SUBSTANTIAL



DURABILITY TEST ASTM D 559

5 HRS IN WATER, DRYING AT 70 DEG C FOR 41

HRS, 12 CYCLES, 18 TO 20 STROKES WITHBRUSH, NEXT REWEIGH THE SAMPLES AND

DETERMINE THE WEIGHT CHANGE.

ALTERNATE

FREEZE /THAW

-24 DEG C FOR 24 HRS

THAWING AT 21 DEG C FOR 24 HRS

12 CYCLES AND REWEIGH SAMPLESLIMITS

GRANULAR SOILS 4%, COHESION SOIL 7%

BASE < 20%, SUBBASE < 30, SHOULDERS < 30 %

IRC 3 (2012) f fl ibl i l d fl ibl



IRC 37 (2012) for flexible pavements include flexible

pavements with Bituminous surfacing over:

(i) Granular base and subbase

ii) Cementitious bases and subbases with a crack

relief layer of aggregate interlayer below the

bituminous surfacing

(iii) Cementitious bases and subbases with SAMIbetween bituminous surfacing and the

Cementitious base layer for retarding the reflection

cracks into the bituminous layer

(iv) Reclaimed Asphalt Pavement (RAP) with or withoutaddition of fresh aggregates treated with foamed

bitumen/ bitumen emulsion.

(v) Use of deep strength long life bituminous

pavement



Base

1. Granular(WMM)2. Cement treated

3. Bitumen-emulsion treated

4. Foamed bitumen treated5. HIR/CIR

Some commercially available stabilisers

/cementitious materials/ bitumen-

emulsion make marginal aggregates

suitable for bases



Pavement design modelThe basic approach is same as that of IRC:37-

2001The thrust is to

1.Limit rutting in bituminous layer

2.Limit rutting in non-bituminous layers3.Limit cracking at the top and bottom of

bit. Layer

4. Limit cracking in the cemented layer



Elastic layered approach pavement model

t

v

E1,h1, 1

E2,h2, 2

E3,h3=, 3

z

A three layer flexible pavement

Granular layer

Subgrade

t

BC layerDual wheel load



Rut resistantBC and DBM II

Fatigue resistant

layer DBM

Granular layers

DBM II

Subgrade

DBM I

Pavement life is increased at least twice

by mix design alone.Less thickness for

same design life



(a)

(b)

Figure Cracks at bottom(a) and top(b)

BT BT

Granular base Granular base



CRITERIA 1



Min 7 day UCS of cementitious base = 4.5 to 7 Mpa

(IRC:89- 2010)

E(Mpa)= 1000 UCS

Min 7 day UCS values for the cemented subbase : 1.5

MPa to 3.0 Mpa(IRC:89-2010)

Initial modulus of cemented GSB: 2000 MPa to 4000

Mpa

Low strength cementitious material may not retain the

initial modulus because of cracks due to shrinkage,construction traffic as well as wetting and drying

A lower modulus of 600 MPa may be adopted for

design(SA)



Fatigue of cemented layer(Austroads)

12804.0

])191/113000(

[

E RF N

RF=1 for heavy commercial vehicles>1500

Valid for E in the range 2000-10000 MpaRecommended RF=2 for truck traffic less

than 1500 per day



Fatigue Relationship for various types of cemented materials

40

60

80

100

120

140

160

180

200

100000 1000000 10000000 100000000 1000000000 10000000000

Number of Load Repetitions

A p p l i e d S

t r a i n

( m i c r o s t r a i n )

Appli ed Strain (microstrain) (µε)



A SAMI of CRMB/PMB must be provided

over the cemented layer to delay the cracks

propagating to the bituminous layer.

A granular of thickness 75 to 150mm

sandwiched between the bituminous layerand cemented layer may extend the fatigue

life of the bituminous layer by about three

to five times than without it

Cracking of cemented base is the end of

design life of the pavement

Use of cemented base to obtain



Use of cemented base to obtaincost effective pavements

(SA/AUSTRALIA/US)

75mm to 150mm of aggregate layer

increases the fracture life of the bit.top

by 3 to 5 times. Neglect residual life of

asphalt layer if its thickness<175mm AUSTROADS

BC/DBM layer

Aggregate

Layer

Cementitious

layer

Gran.subbase



Fatigue fracture life as per the IRC:37

( For 80% reliability)

Nf =2.21 x 10-4 x (1/ t )3.89 x (1/E)0.854

E values are given in the draft

One has freedom to select a binder

depending upon experience

Rutting of subgrade has not been aproblem as per current IRC:37



Fatigue equations for 90% reliability

Nf = 0.711 * 10-04 x [1/εt]3.89 * [1/E]0.854Effect of bitumen content and air void

Nf = 0.5161 * C*10-04 x [1/εt]3.89 * [1/E]0.854

WhereC= 10M, .. (AI,Shell)

Va =air void and Vb=volume of bitumen,

Nf = fatigue life, єt= maximum tensile strain at the

bottom of DBM



CRITERIA 3



Rutting in flexible pavement

If elastic vertical subgrade strain, Єz is

limited, Єz gets limited in all layers

Good correlation between rutting on

surface and Єv Єp/ Єz= K x (N)c

Єp= Plastic deformation

Such an approach was adopted byother countries also

MEPDG uses another approach



5337.48 )/1(101656.4 z

Nr

Rutting equation for 80%

and 90% reliability

N= 1.41x 10-8x [1/εv] 4.5337

Above Eqs. guards against ruttingin granular layer and the subgrade

only



RESULTS OF IIT PAV PROGRAM



250 250 250 250 250 250 250

80 90 110 13090 110 130

100 100100

100

100100

10060

5050

30 40

5050

4050

50

0

100

200

300

400

500

600

700

2-5 6-10 11-20 21-30 31-50 51-100 101-150

P a v e m e n t T h i c k n e s s i n m

m

Traffic in msa

CBR 5%

CT Subbase-D+F(E=600 Mpa) CT Base(E=5000 Mpa) Aggregate Layer (E=450 Mpa) DBM SDBC(upto 5msa)/BC

Bituminous pavements with cemented base and cemented

subbase having 100mm of aggregate interlayer for crack

relief. Upper 100mm of the cemented subbase is the

drainage layer(BC and DBM at OBC)



1. Low strength base develops only fine

cracks and the reflected cracks in BT also

would be fine and impermeable to water(Trial sections in TN)

2. Higher strength cemented layers may

develop wide cracks which may reflect tothe bituminous layer(PCA)

3. Cemented bases performed well in tial

sections (i)Krishnagiri-Topurghat Road

project(Tamilnadu) FWD and BB deflection

(ii) Ahmedabad-Udaipur(NH8) (iii)

Jamnagar refinery in Gujarat



(iv) Ahmedabad-Baroda expressway

(v) Achad-Manor in Maharashtra

(v) Chitradurga haul road in Karnataka(FWD)

(vi) Durbal-Hanjik Road in Srinagar

(viii) Reasi-Pauni Road in Jammu(Dist:Katra)

Cement content around 4 to 6%

ADVANCEMENT MIXING/MILLING



Rotavator Zipper

Milling and Mixing Writgen

FULLY MECHANISED STABILIZATION MACHINE- STEHR

ADVANCEMENT – MIXING/MILLING



SPECIAL EQUIPMENTS USED FORSTABILIZATION PROJECTS IN INDIA



STEHR EQUIPMENT



TECHNICAL DATA-STEHR

Integrated, dustfree stabilizer with John Deere Engine:• Working width: 2400 mm

• Working depth: 0-400 mm

• Total length: 12 m

• Total width: 2,80 m

• Total height: 3,15 m

• Total weight: 22800 kg

• Recycled Area: Max 700 sq mtr/hr ( upto depth 400mm)



EXECUTION –STEHR -1

1- SPREADING AND LEVELLING

2- MIXING

3- LAYING

4- STABILIZED LAYER

BEFORE COMPACTION



National Highway Application in India

GSB – 200mm

Sub grade – 300mm

WMM – 250mm

BC - 40mm

DBM - 60mm

GSB – 100mm

Embankment Local Soil (CBR 12)

Soil + 4% RBI – 225mm (Borrowed Soil)

SDBC - 40mm

20 MSA, 15 % CBR

RBI Method = 365 mm (450mm IRC 37)

Conventional= 550 mm

IRC 37 30 msa, 3% CBR

RBI Method = 500 mm

Conventional= 810 mm



CONSTRUCTION USING THE

WMM PLANT



National Highway Application in India



CONSTRUCTION USING

ROTORVATOR



VIEW OF MACHINE PARTS – RBI BAGS -4



PWD Jammu--Pic no 125% 10 MM Aggregate+25%20

MM Aggregate+50% Stone

Dust+4% RBI Grade 81—

125 MM



Suratgarh Rajasthan—

Pic no 2 PMC 20 MM

70% Soil+30% Aggregate+4% RBI Grade 81—150 MM

GSB—

100 MM



Affordable in Rajasthan--Pic no 4 SDBC-25 MM

75% Soil+25% 20 MM Aggregate+4%

RBI Grade 81—150 MM



Dadu Phagi Road in HP--Pic no 3

BC-40 MM

25% 10 MM Aggregate+25% 20 MM

Aggregate+50% Stone Dust+5% RBI Grade 81

GSB Existing

Subgrade Existing



Bidar -Karnataka



IN-PLANT STABILIZATION/RECYCLING

IN SITU STABILIZATION/RECYCLING



IN-SITU-STABILIZATION/RECYCLING

CONDITION BEFORE RECYCLING



CONDITION BEFORE RECYCLING

Existing Pavement Condition Before Recycling

EXISTING PAVEMENT CRUST



EXISTING PAVEMENT CRUST

Existing Pavement Crust Before Recycling

IN-SITU-RECYCLING WITH STABILIZER



Milling & mixing with Stabilizer & Water using IN-Situ-

Recycler

COMPACTION



COMPACTION

Compacting Recycled Layer

AFTER ROAD MARKING



AFTER ROAD MARKING

Cold Recycling Stretch after two months

EXISTING PAVEMENT CONDITION



EXISTING PAVEMENT CONDITION

Poor Pavement Condition

MILLING OF EXISTING PAVEMENT



MILLING OF EXISTING PAVEMENT

Milling is in progress with Asphalt Zipper

MIXING STABILIZER



MIXING STABILIZER

COMPACTION OF MIXED MATERIAL



COMPACTION OF MIXED MATERIAL

Compaction in Progress-Initial Compaction using Tandem

Roller & Final Compaction using Pneumatic Tired Roller

Initial Compaction Final Compaction

COMPACTED STABILIZED



RECYCLED SURFACE

Compacted Surface of Stabilized Recycled Layer

SDBC IN PROGRESS



Primed Recycled Surface

methods of soil and base stabilization

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