lecture until jan. 29

8/9/2019 Lecture Until Jan. 29

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CE 742 Pavement Systems Engineering

PAVEMENT MATERIALS


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Effective CBR (IRC 37)


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Dynamic Cone Penetrometer (DCP)


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Resilient Modulus of Soil


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Unconfined Compressive Strength (UCS) S


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Resilient Modulus


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AGGREGATES


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Aggregate is the major component of all materials used

in road construction It is used in granular bases and sub base, bituminous

courses and in cement concrete pavements (GSB, WBM,

WMM, HMA)

Introduction - Aggregates


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Types of aggregate

Most of the aggregates are prepared from natural rock and the propert

aggregate depend on properties of rock:1. Igneous rocks : Basalt, Granite

2. Sedimentary rocks: Sandstone, Limestone, Dolomite,

Siltstone, Shale, Chalk

3. Metamorphic rock: Marble, Quartzite, Gneiss

Acidic:

Silica Content > 66 %; Basic: Silica Content < 55%

Silica content increases, acidity increases and hence negative charge

Water Affinity:

Hydrophilic: Water loving

Hydrophobic: Water hater

Particle Charge:

Positive Charge: Limestone, Calcareous

Negative Charge: Sandstone, Quartz, Gravel, Basalt


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Aggregate Surface Charges

Nature of Bitumen (Acidic or Base) ?

AcidicBase

Bonding between aggregate-asphalt binder (moisture damage)?


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Physical Properties of Aggregates


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Coefficient of Thermal Expansion (CT

CTE increases with amount of silica

Sandstone> Granite> Basalt > Limestone

Higher CTE, higher thermal stress Concrete Pavement: Joint spacing, joint width, temperature stresses


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Basic Laboratory Tests on Aggregate

Atterberg Limit on FinesPlasticity Index

GradationDense, uniform, gap graded Shape of Aggregates: Angular, Elongated,

Flaky

Gradation

Impact Value

Abrasion Specific Gravity

Proctor (OMC-MDD)

Water Absorption

Sand equivalent value


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Aggregate Size Coarse Aggregates: Retained 4.75 mm sieve

Fine Aggregates: Passing 4.75 mm sieve

Nominal Maximum Aggregate Size: Largest sieve that retains < 10% Aggregates

Maximum Aggregate Size:

Smallest sieve through which 100% aggregates pass

Stockpile A

NMAS: 9.5 mmMAS: 12.5 mm

Stockpile B

NMAS: 4.75 mMAS: 9.5 mm


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- Larger maximum size

+ Increases strength

+ Improves skid resistance

+ Increases volume and surface area of agg whic

decreases required AC content

+ Improves rut resistance+ Increases problem with segregation of particles

- Smaller max size

+ Reduces segregation

+ Reduces road noise

+ Decreases tire wear

Aggregate Size


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Percent Crushed Faces

0% Crushed 100% with 2 or More

Crushed Faces


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Coarse Aggregate Angularity Criteria

Traffic Depth from Surface

Millions of ESALs < 100 mm > 100

mm< 0.3

< 1

< 3

< 10

< 30

< 100

100

55/--

65/--

75/--

85/80

95/90

100/100100/100

--/--

--/--

50/--

60/--

80/75

95/90100/100

First number denotes % with one or more fractured fac

Second number denotes % with two or more fractured f

Q lit C t l


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Quality Control

MORTH, 5th Revision (2013) Water absorption > 2%, wet aggregate impact test should be carried out as per IS5640

Soft Aggregates like Kankar, brick ballast, and laterite shall also be tested for wet impac

Aggregate impact : GSBMax. 40%; WBM/WMM30% Max

Los Angeles Abrasion value: WBM/WMM40% max.,

Combined flakiness and elongation: WBM/WMM- 35% max.

Plasticity index : Maximum 6%

Liquid Limit : Maximum 25%

CBR: Minimum 30%

Layer Thickness:

Static 80-100 kN static roller: Thickness 100 mm

Vibratory roller: 200 mm


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Performance Tests on Aggregates

California Bearing Ratio (CBR)

Unconfined Compressive Strength (UCS)

Dynamic Cone Penetrometer (DCP)

Resilient Modulus (MR)

Flexural Strength

Durability

Direct Shear

Permeability

Stripping Value


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Aggregate Image Measurement System (AIM

Angularity

Texture Sphericity

Flaky and Elongation

Form


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Gradation

Specified Gradation for BC


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Sieve Sizemm

Grading I Grading II

50-65 mm(19 mm nominalaggregate size)

30-45 mm(13 mm nominalaggregate size)

26.5 100 -

19 79-100 100

13.2 59-79 79-100

9.5 52-72 70-88

4.75 35-55 53-71

2.36 28-44 42-581.18 20-34 42-58

0.60 15-27 26-38

0.30 10-20 18-28

0.15 5-13 12-20

0.075 2-8 4-10

Specified Gradation for BC


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Specific Gravity of Aggregates

Bulk Specific Gravity Apparent (Net) Specific Gravity

Effective Specific Gravity

Specific Gravity:

Ratio of the weight of an object to theweight of an equal volume of water

(at std. temperature & pressure)


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Oven DrySurface Saturated

Dry

Wet

Moisture Content

Net Volume = Weight in air - weight in water

Bulk Volume = SSD weight weight in water (Net Volume + Permeable Voids)

Effective Volume = Bulk Volume Volume Filled with Bitumen (Bitumen absorb


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Bulk Specific Gravity (

) ( )

( +)

A () ( )

Effective () ( )

( =

SSD Specific Gravity()

( +)

=1

Pb = % asphalt content

Gmm = Maximum specific gravity of a loose mix

Gb = Specific gravity of binder

Specific Gravity of Aggregates


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Blending of Aggregates

Combined Specific Gravity =100

+

+.

+

Combined Water Absorption = 1 1+2 2


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Resilient Modulus of Aggregates

Sample Size: 6 Diameter x 12 Height

Confining Pressure: 3, 5, 10, 15, 20 psi

Deviatoric Stress: 3, 6, 9, 15, 20, 40 psi

Modelling : Using bulk stress MR = 1

Resilient Modulus (IRC 37-2012)

= 0.2 0.45

h = thickness of granular layer (mm) = Resilient modulus of subgrade (MPa)

= Resilient modulus of aggregate layer (MPa)


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BITUMEN


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Bitumen (Asphalt Binder)Bitumen is a hydrocarbon material (C, H, N, O, S)

produced by distillation of petroleum crude

Chemical Com

- Asphaltene

- Maltene- Resin


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Desirable Properties of Bitumen

1. It should be fluid enough at the time of mixing to coa

aggregate evenly by a thin film

2. It should have low temperature susceptibility

3. Bitumen should have good amount of volatiles in it, and it sh

not lose them excessively when subjected to higher temperature

5. The bitumen should be ductile and not brittle

6. The bitumen should have good affinity to the aggregate

should not be stripped off in the continued presence off water

Application of Bitumen: Hot Mix Asphalt, Flexible

Pavements, Emulsion, Cutback, Rejuvenator


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Penetration

Binder Grading Systems

Softening

PointViscosity Grade

Modified Bitumen

PMB 40 Crumb RubberCRMB 60

Unmodified Bitumen

VG30, VG40

B i L b t T t Bit


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Basic Laboratory Tests on Bitumen

Penetration

Softening Point

Viscosity (Vacuum Capillary Viscometer or Brookfield Visco

Ductility

Flash and Fire Point

Solubility

Spot Test Mass Loss

Specific Gravity

Separation Test


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IS: 73-2013Indian StandardPaving BitumenSpecification (4th Revision)

Viscosity Grade Bitumen

IRC:SP:53-2010Guidelines on Use of Modified Bitumen in Road Constructions (2nd R Polymer, Natural Rubber and Crumb Rubber Bitumen

IS: 15462: 2004: Polymer and Rubber Modified BitumenSpecification

Polymer, Natural Rubber and Crumb Rubber Bitumen

IS: 702-1988Specification for Industrial Bitumen

Penetration and Softening PointUnmodified Bitumen

IS:15808 : 2008Multi-Grade Bitumen for Use in Pavement ConstructionSpecificat Absolute viscosity at 60 C; MGB 500 (hard); MGB 200 (soft)

Indian Codes

B kfi ld Vi it


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0

1000

2000

3000

4000

5000

6000

110 120 130 140 150 160 170 180 190 200

Viscosity(cP)

Temperature (C)

Comparison of Viscosity at varying temperature

VG

PM

CR

VG

Brookfield Viscosity

Mixing Temperature: 17020 mPa.Compaction Temperature: 28030 m

1 cPoise = m Pa.s

1 Poise = 0.1 Pa.

Performance Tests on Bitumen


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Performance Tests on Bitumen

Elastic Recovery

Chemical Analysis

Shear Modulus and Phase Angle

Rutting and Fatigue Performance

Short Term and Long Term Aging

Dynamic Shear Rheometer


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Dynamic Shear Rheometer

Sample Size:

Diameter : 25, 8, 4 mm

Thickness: 2, 1 mm

Output: Shear Modulus and Phase Phase angle: 0 (pure elastic), 90 (v

Shear Modulus


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Shear Modulus

Rutting Factor- G*/Sin ( based on dissipated energy concept)

- Usually for unaged or RTFO/TFO- Minimum value 1 kPa (unaged), and 2.2 kPa for TFO and RTFO

Fatigue Factor- G*Sin

- Usually for PAV aged binder

- Maximum value: 5000 kPa

Aging of BitumenShort term aging

Plant and Production Aging Simulate in laboratory using

Rolling thin film oven (RTFO) or thin film oven (TFO)Long Term Aging

Field aging

Simulate in laboratory: Pressure Aging Vessel


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0

2

4

6

8

10

12

14

16

60 65 70 75 80 85 90 95 100

G*(kPa)

Temperature (C)

Comparison of High Temperature Grade

VG 10

VG 30

PMB 40

CRMB 60

Multi Stress Creep Recovery (MSCR)


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0

100

200

300

400

500

600

700

222 224 226 228 230 232 234

Strain(%)

Time (sec)

Elastic Recovery Comparison (3.2 kPa)

CRMB 3.2 kPa

PMB 3.2 kPa

300

800

1300

1800

2300

2800

3300

3800

222 224 226 228 230 232 234

Strain(%)

Time (sec)

Elastic Recovery VG 10 & VG 30 (3kPa)

Multi Stress Creep Recovery (MSCR)

Loading time: 1 sec, Rest period: 9 sec.

Stress level: 100 and 3200 Pa

# Cycle: 10 at each stress level.Output: Recovery, Polymeric nature

T t S tibilit


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Temperature Susceptibility

1. Penetration Index (PI) =20500

1+50

A: Temperature susceptibility: Slope of the straight line plot between the logarith

penetration and temperature

A=log ()log ()

;

2 = taken as R&B temperature, (& ) = 800

Increase in A value indicates high temperature susceptibility

A increases PI decreases

PI range: +1 to -2. PI


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Stiffness of Binder

1. Estimate Using Nomograph (Van der Pol, 1954)

Inputs: Time of loading

Frequency f =1

2

R&B temperature

Penetration index

Temperature

Temperature difference: T (R&B)T (test temperature)

2. Measure in Laboratory using Dynamic Shear Rheometer

Conduct test at any frequency and temperature

IS: 73-2013 Indian Standard Paving Bitumen


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IS: 73 2013 Indian Standard Paving Bitumen

Viscosity Grade 7 day Avg. Max Air Temp (C )

VG10 457 day average maximum air temperature (C ) not

less than 5 years from start of the design period

Test VG10 VG20 VG30 VG40

Penetration, 25 C, 100 g, 5 s, 0. 1 mm (Min) 80 60 45 35

Absolute Viscosity at 60 C, Poises (Min) 800-1200 1600-2400 2400-3600 3200-4800

Kinematic Viscosity at 135 C, cSt (Min) 250 300 350 400

Flash Point, C (Min) 220 220 220 220

Solubility in TCE, % (Min) 99 99 99 99

Softening Point (R&B), C (Min) 40 45 47 50

Residue

Viscosity ratio at 60 C (Max) (RTFO Aged/Unaged) 4 4 4 4

Ductility at 25 C, cm (Min) 75 50 40 25

Hi h t M Ai T t

IRC: SP: 53-2010Properties of Modified Bitumen


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Highest Mean Air Temperature

Lowest Mean Air Temperature

>-10 C and -10 C and -

Penetration, 25 C, 100 g, 5 s, 0. 1 mm 60-120 50-80 30

Sofetining Point (R&B), C (Min) 50 55

Frass breaking point, C, Max -20 -16 -

Flash Point, C (Min) 220 220 2

Elastic Recovery, 15 C (Min) 50 60

Complex Modulus (G*/Sin delta), Min 1.0 kPa,10 rad/sec (C) 58 70

Separation, difference in sofetining point (R&B), C (Max) 3 3

Kinematic Viscosity at 150 C, Poise 1-3 3-6 5

TFO Residue Tests

Loss in mass (%), Max 1 1

Increase in sofeting point, C, Max 7 6Reduction in Penetration at 25 C, %, Max 35 35

Elastic Recovery at 25 C, Min 35 50

Complex Modulus (G*/Sin delta), Min 1.0 kPa,10 rad/sec (C) 58 70


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EMULSION

Bitumen Emulsions


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Application of Emulsion: Cold Recycling, Ready mixes, micro

surfacing, maintenance and patch work, tack coat, prime coat

Bitumen is broken up into fineglobules and kept suspended inwater by addition emulsifier of

different charges

Bitumen content in emulsionranges from 40 to 60% and theremaining portion is water

Emulsifiers usually adopted aresoaps, surface active agentsand colloidal powders (1.5 to1%)


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Seal Coat

Tack Coat

E l i G di S t


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Setting Time

Emulsion Grading Systems

Particle

ChargeModification

Rapid Setting,Medium Setting, and

Slow Setting Cationic and Anionic

Polymer or LatexModified/

Unmodified

Examples: CRS, SS, CMS-P, RS-P

Basic Laboratory Tests onEmulsions


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Emulsions

Residue on 600 micron sieve: Homogeneity of samp

Viscosity by Saybolt Furol Viscometer: To spray and

coat the aggregate

Storage Stability: Settling rate, help to ascertain

proper mixing prior to use Particle Charge: Affects the bonding between aggregate and emulsion

Distillation: Percentage of binder present in emulsion phase

Coating Ability and Water Resistance

Coagulation at Low Temperature: Ensure that no foreign adm

Emulsion Codes:

IS 88872004 - Bitumen Emulsion for Roads (Cationic Type)

IRC SP 1002014: Use of Cold Mix Technology in Construction and

Maintenance of Roads Using Bitumen Emulsion

Laboratory Tests EmulsionsResidue


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Residue Residue by Evaporation: Estimate water content Ductility: Fatigue and thermal cracking

Elastic Recovery: Degree to it recovers to its original shape after

unloading

Penetration: Cracking potential and mixture consistency

Softening Point: High temperature

Solubility in Trichloroethylene: Impurity

Breaking of Emulsions

When applied on road, breaks down and the binder starts binding thaggregates, though the full binding power develops slowly as and when thwater evaporates.

First sign of breakdown is change in colour of film from chocolate brown tblack


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