CHAPTER 1: HIGHWAY MATERIALS

byDr Haryati Yaacob

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1. INTRODUCTION

2. MALAYSIAN’S ROAD SYSTEM

3. PAVEMENT LAYERS

4. PAVING MATERIALS

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INTRODUCTION

The needs for roads stems from the invention of wheels in Samaria –3000SM

Among early roads:

■ Silk Route – 2600BC ,silk , China- India

■ Persian Empire- silk, porcelain and wood crafts, China- Europe

■ Britain/Europe – 2500BC, log-raft type

■ India – bricks, piped surface drainage systems

■ Mesopotamia & Egypt – paved in asphalt and bricks, Pyramid

■ Roman roads – greatest road building era, 3 structured layers (levelled earth, gravelled surface, paved)

Tresaguet (1716)

cambered formation, differential settlement problem

John Metcalf (1717)

Blind Jack (musician & horse trade), built 290 km in Yorkshire, proper drainage & large stone foundation

Gravel

Excavated

road material

Large stone

Foundation

Thomas Telford (1757)

civil eng in Britain, built 1600 km ++, flat formation, other layers even thickness

John Macadam (1756)

true highway engineering specialist, surveyor, cambered formation, other layers even thickness, use small angular aggregats, cheaper and easier

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INTRODUCTION

Types of road surface:

Earth road

Gravelled surface

Flexible pavement – asphaltic concrete

porous pavement/porous asphalt

stone mastic asphalt

surface dressing

Rigid pavement- Concrete road

Interlocking block pavement

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Malaysia Road System

Road network system

•State road- 73 850 km

•Federal roads – 18 015 km

•Toll roads- 1490 km

•TOTAL- 93,355 km

98.5% are paved (asphalt or concrete)

Road categories based on funds for construction and maintenance for administration purpose:

Road categories

Toll Road

Federal Road

State Road

Municipal/City

Council

Other Roads

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Federal Road - connects entry points and major cities- federal gov

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Toll Highway- concession company (MHA) design, built & operates , alternative

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State Road- providing intra-state travel, state fund

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Local Council Road- township council including built by developer

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Small Road- jalan kampung by district office from state funds

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Two classification for geometric design purpose:

Urban – U Rural – R

Malaysian Road System

Mooc 2832

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Pavement layers

Mooc, 2832

Sub - Grade

Mooc, 2832

Sub –Grade: Unsuitable Materials

1.Silt, peat, logs, stumps, toxic material and mud

2.Any material • Consists of highly organic clay and silt;

• Having LL > 80% and/or PI > 55%;

• Susceptible to spontaneous combustion;

• Containing large amounts of roots, grass and other vegetable matter.

Purpose – determine bearing capacity of material against standard crushed

aggregate

1.COMPACTION TEST (determine MDD and OMC)

mold 2.3L, hammer 4.5 kg, 62 blows/layer, 5 layers, 5 different mc, obtain Bulk

Density >>> Dry density >>> plot DD vs. MC

2. CBR TEST (determine CBR at 95% compaction)

3 mold at OMC, vary no. of blows to obtain 95% compaction, calculate DD, soak, drain, CBR test, plot Load vs. Penetration graph, calculate CBR at 2.5 and 5.0mm, CBR vs

DD>>CBR at 95% MDD

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Compaction

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Compaction

DD vs. MC

Moisture Content

Dry Density

Compaction

Curve

MDD

OMC

Exercise 1.7.1Compaction Data

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CBR

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CBR

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CBR Testing

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2

3

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CBR 1

0 2 4 6 8

0

2

4

6

8

10

12

Penetration, mm

Load

, kN

CBR (2.5mm) = (h/13.24) x 100CBR (5mm) = (y/19.96) x 100

h

y

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CBR 2

0 2 4 6 8

0

2

4

6

8

10

12

Penetration, mm

Load

, kN

CBR (2.5mm) = (h/13.24) x 100CBR (5mm) = (y/19.96) x 100

h

y

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CBR 3

0 2 4 6 8

0

2

4

6

8

10

12

Penetration, mm

Load

, kN

CBR (2.5mm) = (h/13.24) x 100CBR (5mm) = (y/19.96) x 100

h

y

Exercise 1.7.2 & 1.7.3CBR Data

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CBR vs. DD Data

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CBR vs. DD

Exercise 1.7.4

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•CBR value :• SG: 3- 15%• SB: 15- 40%• RB: 60- 100%

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Sub base:

Function

Assist in load

spreading

Provide platform for construction

Drainage layer

Protection to the

exposed sub-grade

Separator

Sub -base

Mooc 2832

Road base : Main spreading layer

Dry Bound Macadam (natural interlock)

• Aggregate interlocking

• 1st layer –course agg : 75-100mm

• 2nd layer- fine agg : 25-50mm

Wet mix macadam

• Agreggate + 2-5% water (plant)

• Less segreagation , easy to compact.

• 200-300 mm

Cement Stabilisedbase

-Aggregate + cement (3-6%) (site/plant)

-Cure before laying surface

Bituminous Macadam Roadbase

• Agg+ filler+ bitumen (4-5%) (plant)

• Costly

Composite

-1st layer- unbound material

-2nd layer- bound material bituminous macadam/cement

bound

Surface layer

Mooc 2832

ROAD PAVING MATERIALS

Road Paving

Materials

Aggregate – carry traffic load, main

interlocking structure

Filler – fill small voids, durable mixture,

increase viscosity of binder, reduces binder run-off

Bitumen – bind aggregates

producing strong, durable & stable

mixture

Natural Aggregate

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Artificial aggregate – steel slag waste from ore to produce iron, steel, nickel, etc.

Types of Aggregate

Course aggregates

( > 2.36mm)

Fine Aggregates

(2.36 – 75 micron)

Filler

(< 75 micron)

For road construction, aggregate classified according to size:

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Types of Aggregate

1. Coarse – ( > 2.36mm) crushed aggregate

2. Fine – (2.36 – 75 micron) fine crushed aggregate, sand (river, mining)

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3. Filler – (< 75 micron) fine materials such as cement, lime, crushed aggregate dust

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Aggregate Size Definitions

• Nominal Maximum Aggregate SizeLargest sieve size that retains

some of the agg, but not more than 10%

• Maximum Aggregate SizeSmallest sieve size which 100% of

the agg pass

1001009072654836221594

100998972654836221594

Aggregate properties

Aggregate Properties

STRENGHTH

crushing, impact, during construction & traffic load (ACV,

TFV,AIV, LAAV)DURABILITY

resistance to disintegration

under weathering

(Soundness)

SHAPE AND SURFACE TEXTURE

interlocking, resistance to sliding, affect

strength (FI, EI)

AFFINITY

properly coated by

binder (Coating and

stripping)

GRADATION

quality & pavement strength (Sieving)

RESISTANCE TO WEAR

(HARDNESS)

rounded under traffic, skid

resistance (PSV)

RELATIVE DENSITY AND ABSORPRION

stripping, drying time, mix design (SG, WA)

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ACV (Aggregate crushing value : Strength ) Resistance to crushing under gradually applied compressive load

•Passing 14, retained 10, 3000gm

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ACV - Process

3 layers, compact each layer 25 times

Compression machine, 10 minLoad 0-400kn ACV = (weight pass 2.36mm) x100%

(weight original)

• TFV• Similar to ACV test

• TFV= 14f/ (4 +y)

f= load

y= percent crushed over 2.36 mm ( 7.5%- 12.5%)

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AIV (Aggregate Impact value - Strength) : Resistance to sudden shock or impact

Pass, 10, retained 1425 times rodding15 times impact loading.

AIV = (weight pass 2.36mm) x 100%(weight original)

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LAAV (Los Angeles Abrasion Value: Strength) Degradation under combination of abrasion or attrition, impact, and grinding

-5000g, rotate 500

revolutions with

33 rpm

- Passing 1.7 mm

LAAV = (weight pass 1.7mm) x100%(weight original)

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Soundness : Durability- resistance to disintegration due to cycle of wetting and drying, heating and cooling (weathering)(AASHTO T 104)

-Soak in magnesium /sodium sulfate for 16/18 hrs-Dry, 105˚C, 16-18 hrs-5 cycles

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Soundness

Before After

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Flakiness & Elongation

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Flakiness & ElongationApparatus

-Flaky- thickness is less than 0.6 times its average dimension.-6.3-63mm-pass the slot

- Long- thickness is more than 1.8 times its average dimension- Retained the slot

FI = (weight pass slot) x 100%(weight original)

EI = (weight retained slot) x 100%(weight original)

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Coarse Aggregate Specific Gravity and Water Absorption - Relative density, pores, and absorption

-Soaked in distilled water 24 hours-Weight in water –C

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Coarse Aggregate Specific Gravity

Dry with damp towel -B

Dry oven 24 hours and weight - A

• A = in water

• B = dry towel

• C= dry oven

• WA= (B-A/A ) x 100%

• SG bulk = A/(B-C)

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Coating and stripping test- properly coated by binder

• Hidrophilic (bad) and hydrophobic (good)

• Mix and heat bitumen and agg

• Soak 16-18 hrs with distill water

• Determine the coated surface area whether more or less than 95%.

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Coating & Stripping

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PSV (Polished Stone Value) – resistance to polishing effect by traffic. Sample Preparation

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PSV Sample

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PSV Polishing

-406 mm diameter wheel-200 mm diameter rubber tyre (390kN)-water + corn emery flour (3 hours, abrasion ) water + emery flour (3 hours, polishing)

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PSV Skid Tester

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Sieve Set

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Sieve Analysis

Analisis Ayakan

0

10

20

30

40

50

60

70

80

90

100

0.01 0.10 1.00 10.00 100.00

Sieve Size, mm

Perc

ent

Passin

g,

%

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Bitumen

US UK

Bitumen Bitumen & tar

Asphaltic cement Bitumen

Ashaltic concrete Asphalt= Bitumen + Aggregate

** Asphalt binder

BitumenTwo types of binder -

(interchangeably due to misconception, diff. origin, chem. composition, physical

characteristics.)

Tar – black-brown, adhesive quality, a product of coal (insoluble in petroleum, high temperature susceptibility, heavier, health

hazards, distinct odor)

Bitumen – viscous liquid/solid, black or brown in color, having adhesive qualities, consisting essentially of hydrocarbons,

derived from petroleum or occuringnaturally and soluble in carbon disulphate

(80-85% C, 10% H)

Refining of Crude Petroleum

Petroleum Distillation

GasolineKerosene

Lt. Gas OilDiesel

Motor Oils

Asphalt

Grading System

Penetration Grading

SuperpavePerformance Grading (PG)

Viscosity Grading

Penetration Grading • Penetration test at 25˚C, 1 Pen= 0.1mm

• 80-100 PEN, new spec 60-70 PEN

• Range- 40-300 PEN

• uses the penetration of the original AC. Tests involved: penetration, softening point, flash point, ductility, solubility, TFOT (penetration & ductility)

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Properties80-100 200-300

min max min max

Penetration 80 100 200 300

Softening Point 45 52 33 43

Solubility 99.0 - 99.0 -

Ductility 100 - 100 -

Flash Point 225 - 200 -

Retained Pen 47 - 37 -

Loss on Heating - 0.5 - 1.0

Drop in Pen - 20 - 25

Temperature25C (77F)

High

Medium

Low

Problem with PEN system??Temperature susceptibility

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•Measure pen and viscosity at 60˚C and 135˚C•Tested on Asphalt Cement (AC) and Asphalt Residue (AR)•Unit poises•AC-10,AC-20, AR- 4000•Tests involved: viscosities, penetration, flash point, solubility, TFOT (viscosity, ductility)•Does not test on low temperature

Viscosity Grading

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■ Historically graded according to penetration and viscosity

■ These tests measure asphalt sample at only one temp, do not give indication of performance at wide range temp

■ Asphalt from diff crude meet PEN and VISC spec of given grade but perform differently during constr. and service (at high & low temp)

■ Performance Grade (PG) asphalt binder (original & modified) measure physical properties throughout its temp range

■ PG binders are graded according to climatic condition they will endure

■ Binder specification based on extreme hot and cold pavement temperature. Tests involved: RV, DSR, BBR, DTT, RTFO, PAV

■ Changes in asphalt properties due to temperature, rate of loading and the effect of aging are considered

Superpave Performance Grading ( PG System)

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The grading system is based on hot and cold

pavement temperature

PG 64 - 22

Performance

GradeAverage 7-day max

pavement temperature

Min pavement

temperature

Superpave Asphalt Binder Specification

Bitumen Test

Penetration –consistency test

(describe the degree of fluidity of AC at

any particular temperature). AC is

thermoplastic (consistency varies

with temperature) ), hardness

Viscosity –consistency

test, resistance to

flow

Softening Point –

consistency, temp at

which phase change occurs

Ductility –elongation before breaking Flash Point –

safety, max safe

operating temp

Solubility –purity

(trichloroethylene)

TFOT– short term aging

Loss on heating-volatility

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Penetration

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Bitumen Sample

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Penetration Apparatus

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Softening Point

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Softening Point Apparatus

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Penetration Index

IP = (1951.4 – 500 log P – 20 SP) / (50 log P – SP – 120.14)

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Ductility Apparatus

-5cm/min, 25˚C-distance where it breaksPotential it cracks

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Ductility

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Flash Point /Cleveland Open Cuptest (Safety)

Thermometer

Cup filled with asphalt

Wand attached to gas line

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Flash Point

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Solubility (Purity)

Dissolved in trichloroethylene filtered through a glass fiber pad

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Tests used in PG grading

• Tests are conducted to reflect pavement performance under various environmental conditions and construction workability

• Rutting & Fatigue Crack – Dynamic Shear Rheometer

• Short and Long Term Aging – Rolling Thin Film Oven Test, Pressure Aging Vessel

• Low Temp Crack – Bending Beam Rheometer, Direct Tension Test

• Construction Workability – Rotational Viscometer

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DSR EquipmentComputer Control and

Data Acquisition

DSR Equipment

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25 mm Plate with Sample

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Area for Liquid Bath

Motor

Parallel Plates with Sample

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RV DSRBBR

Original Properties, Rutting, and Fatigue

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RV

DSR

BBR

run at warm test temps to indicate the ability of binder to resist rutting – 25 mm plate

Rutting

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RV

DSR

BBR

1. after RTFO aging (simulate during mixing and constr) 2. after PAV aging (simulate aging after 7-10 yrs service) – 8 mm plate

Fatigue

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Rolling Thin Film Oven ( short term aging)

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Inside of RTFO

Fan

Air Line

Rotating

Bottle

Carriage

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Bottles Before and After Testing

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Simulates aging of an asphalt binder for 7

to 10 years

50 gram sample is aged for 20 hours

Pressure of 2,070 kPa (300 psi)

At 90, 100 or 110 C

Sample from PAV tested for fatigue (DSR)

or low temp prop (BBR)

Pressure Aging Vessel(Long Term Aging)

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Bottom of

pressure aging

vessel

Rack of individual pans

(50g of asphalt / pan)

Pressure Aging Vessel

Vessel Lid Components

-20 hrs, 2070 kPa

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Pressure Aging Vessel

Courtesy of FHWA

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RVDSR

BBR

low temperature binder propertiesapply static load to simply supported binder beam

Thermal Cracking

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Bending Beam Rheometer

Air Bearing

Load Cell

Deflection Transducer

Fluid Bath

Computer

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Bending Beam Rheometer Sample

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Bending Beam Rheometer Equipment

Cooling

System

Fluid Bath

Loading

Ram

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Is Stiffness Enough?

• No. If binder fail BBR stiffness requirement (max 300 MPa), need to assess strain needed to break specimen.

• Thermal cracking occurs when strain is too great

• Direct tension test• Stretches small beam of binder until breaks (min strain 1%)

• Measures the susceptibility of binder to low temp failure

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Direct Tension Test

D Le

D L

Load

Stress = s = P / A

Strainef

sf

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FHWA

Direct Tension Test

Courtesy of FHWA

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Direct Tension Test

Courtesy of FHWA

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RV DSR BBR

Construction

Workability

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Rotational Viscometer

• Viscosity of original binder measured to insure material can be pumped and handled by HMA plants and construction equipment

• RV capable of measuring viscosity at varying temps and can handle highly viscous modified asphalts

• Viscosity determined from amount of torque needed to rotate a spindle

• Viscosity = ratio of shear stress to strain rate

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Inner Cylinder

Torque Motor

Thermosel

Environmental

Chamber

Digital Temperature Controller

Rotational Viscometer (Brookfield)

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Cutback Asphalts

Liquid asphalt manufactured by adding (cutting back) petroleum solvent to asphalt cement (50-80%)

This will reduce the viscosity for lower application temperatures

Application to aggregate or pavement causes solvent to evaporate, leaving residue on the surface

Divided into three types according to rate of curing:

RC – white spirit

MC - kerosene

SC - diesel

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Cutback Bitumen

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Emulsified Asphalt (Emulsion)

Mixture of bitumen (55 - 65%), water and emulsifying agent passed under pressure tru a colloid mill

Emulsions are made to reduce the viscosity for lower application temperatures

Two most commonly used emulsions:

i. Anionic – electro negatively charges asphalt droplets. Compatible with positive charge aggregate such as limestone.

ii. Cationic – electro positively charges asphalt droplets. Compatible with negative charge aggregates (most siliceous aggregates) such as sandstone, quartz, gravel

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Emulsion

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Emulsion

When mixed or sprayed, it sets or breaks because asphalt droplets reacts with the surface of aggregate and squeezing out the water between them

Evaporation of water – primary mechanism for anionic breakup

Electrochemical process - primary mechanism for cationic

Further graded according to setting rate – RS, MS, SS

Setting rate is controlled by the type and amount of the emulsifying agent

Emulsion are increasingly being used in lieu of cutback due to:

1. Environmental regulations

2. Waste of high energy products

3. Safety

4. Lower application temperature

Foamed Asphalt

• Hot asphalt binder + cold water = steam and trapped tiny asphalt binder bubbles (high volume asphalt foam)

• Used as binder in soil stabilization , stabilizing agent in CIPR

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THANK YOUfor

your attention

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Corduroy & Plank Road

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Paved Roman Road

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Earth Road

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Gravel Road

Flexible Pavements• Hot-Mix Asphalt Concrete

• Distribute loads through layers to subgrade

• Highest quality materials near surface

• Guiding Principle

• Enough total thickness to protect subgrade

• Enough surface thickness to prevent fatigue cracking

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Asphaltic Concrete

- Dense graded, 3 5% air void

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Porous Asphalt

Open graded, 20-25% air void

Porous Asphalt

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What is surface dressing?

Binder

Chippings

Surface Dressing

Rigid Pavements• Portland Cement Concrete Pavements

• Highly rigid, high E

• Distribute loads through bending action over large area of soil

• Must consider strength of concrete

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Concrete Pavement

Pavement types

Type of Pavement & their Load Distribution

Pavement Types & How They Effect the Subgrade

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Interlocking Block

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Interlocking Block

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Interlocking Block

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Quiz1) CBR value reported for material with force of 9.2 and 14.5 kN

at penetration of 2.5 and 5 mm respectively is 0.732) The cost to build asphaltic concrete road is about 3 times

higher than concrete road3) Non-porous pavement has better noise absorbance due to

less air voids compared to porous pavement.4) CBR values can be more than 100%5) Degree of compaction was based on soil characteristics only.6) Interlocking block pavement is suitable for high volume, low

speed road.