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CE 742 Pavement Systems Engineering
PAVEMENT MATERIALS
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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
Blending of Aggregates
Combined Specific Gravity =100
+
+.
+
Combined Water Absorption = 1 1+2 2
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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
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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CE 742 Pavement Systems Engineering
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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