Asphalt mongolian

Asphalt Principles February 2012

Course Objectives

To provide participants with an overview of asphalt

surfacing types and their application

Learning Objectives

Participants will develop an understanding of:

– Asphalt surfacing design and selection

– Asphalt principles and practice

Course Outline

The session will cover:

– Basic Principles of Asphalt

– Use and Types of Asphalt

– Asphalt Mix Design

– Asphalt Production

– Treatment Selection

Basic Principles of Asphalt

Engineered material comprising of Bitumen, aggregate, filler and air voids.

Has engineering properties that can be used for design.

Asphalt is produced according to asphalt mix designs (recipes) based on raw materials

Asphalt is typically produced as a hot material, approx 160oC, and placed as a hot material at >90oC

1. Basic Principles of Asphalt Performance Requirements of Asphalt

Resistance to permanent deformation (ie rutting)

Resistance to fatigue

Durable

Workable (for placement)

Good Skid resistance.

Specialist mixes that have added performance properties such as low noise, low spray generation, or increased resistance to cracking or rutting

1. Basic Principles of Asphalt - Binder

Binder is the ‘glue’ that holds all of the asphalt mix components together.

Can be Class 170, 320, 600 or multigrade bitumen. Class 320 most commonly used

Can include polymer modified binders to enhance the performance properties of the bitumen and is commonly used in high performance mixes such as SMA and OGA

1. Basic Principles of Asphalt - Aggregate

Coarse aggregate ( larger than 4.75mm)

Fine aggregate (between 4.75mm and 0.075mm)

Less than 0.075mm material is called “filler”

Aggregates need to be hard, clean and durable rock with minimal unsound stone

VicRoads Specification 407 and 831 cover the various requirements for asphalt aggregates

1. Basic Principles of Asphalt - Filler

Filler materials are particles that are smaller than 0.075mm.

Can include– natural or manufactured sand– crushed material (crusher dust)– hydrated Lime, Slag, Fly ash, ground limestone,

cement, kiln dust

The actual filler materials vary between mixes and rely on the mix design and available materials

2. Use and Types of Asphalt Use of Asphalt

Structural part of the pavement – deep lift asphalt, typically >150mm depth

Wearing (top) surface of the pavement – typically <40mm

Patching of failed pavement areas

Regulation to improve ride quality and remove depressions

2. Use and Types of Asphalt Types of Asphalt

Hot asphalt, cold asphalt, warm mix, warmix and premix

Asphalt for wearing surfaces

Asphalt for structural layers

Various sizes of asphalt mix -7mm, 10mm, 14mm, 20mm, 28mm

Binders– Bitumen, Emulsion, Polymer Modified Binder


Different types of asphalt wearing surfaces

– DGA Dense Graded Asphalt

– SMA Stone Mastic Asphalt

– OGA Open Graded Asphalt

– UTA Ultra Thin Asphalt (UTA, Novachip)

– RGG Regulation Gap Graded Asphalt

Austroads Asphalt Guide

2. Use and Types of Asphalt

Dense Graded Asphalt

– Most common asphalt type

– Dense, continuously graded aggregates and filler

– Used for structural layers in asphalt pavements (Types SI, SS and SF)

– Used for Wearing courses on both granular and asphalt pavements (Types H, V and HP)

Dense Graded Asphalt


Stone Mastic Asphalt

– Uses gap graded aggregates with a larger proportion of coarse aggregates that interlocks give a strong interlocked matrix

– Includes fibres and a Polymer modified binder

– Used as a wearing course only

– Provides a strong and robust surfacing that has increased resistance to rutting and cracking.

Stone Mastic Asphalt


Open Graded Asphalt

– Wearing course only

– Uses predominantly coarse aggregates and small amounts of fine material

– Provides a mix with a high volume of air voids

– Used as a textured, porous surfacing that assists with noise and spray reduction

– Used almost exclusively on Freeways

– Expected life up to about 12 years

Open Graded Asphalt


Ultra Thin Asphalt

– Used as a wearing course only

– Similar properties to OGA but to a lesser extent

– Developed to be placed in thin layers (typically 25mm)

– Used where an asphalt surface is desirable but levels are an issue, (Kerb and chanel or an as alternative to sprayed seal surfacing

– Expected life 10-12 years

Ultra Thin Asphalt


Regulation Gap Graded Asphalt

Primarily used as a regulation layer to even out surface roughness prior resurfacing

Increased binder content and gap graded aggregate

Has greater workability and can be placed in very thin layers and ramped or feathered out to zero depth

Gap Graded Asphalt


Different types of DGA asphalt for structural layers– Type SI Structural Intermediate

• Multipurpose for heavy duty pavements, or base course for medium duty pavements

• Type SP Structural PMB (intermediate layer)• High resistance to deformation at very heavily trafficked

intersections– Type SS Structural Intermediate for Stiffness

• Stiffness layer for large scale heavy duty asphalt pavement

– Type SF Structural Fatigue• Fatigue resistant base course for heavy duty pavements

(must be covered by 100mm of other asphalt)

3. Asphalt Mix Design

Mix design undertaken by Asphalt production company.

Selection of “Ingredients”

– Aggregate type

– Filler material

– Aggregate grading

– Binder type & Content

3. Asphalt Mix Design

Source : AAPA

3. Asphalt Mix Design VicRoads Registration System

Contractual requirement of all VicRoads Contracts that mix designs used on VicRoads works must be Registered.

Mixes can be registered as:– General Mix

• Complies with VicRoads Standard Specifications.

– Non Standard Mix • Proprietary and other mixes that do not comply in all

respects with the requirements of this Code of Practice but where successful field trials have been undertaken for a period of at least three years and the mix performance continues to be closely monitored.


– Experimental Mix – • A mix that does not comply with the requirements

of this Code of Practice and for which there is little or no history of successful performance and requires more trials to be undertaken and monitored before it is registered as a Non Standard or Conditional mix.

– Conditional Mix – • Mixes which do not comply in all respects with the

requirements of Standard Specifications but which are considered appropriate for use subject to conditions attached to the registration.


– Superseded Mix• Superseded by another registered mix but details

are retained for record purposes.

– Withdrawn Mix• Withdrawn from use because of unsatisfactory

field performance but details are retained for record purposes.


All mix designs reviewed and recorded by Technical Consulting and stored in a database.

Registrations last for two years and must be renewed

New mix designs required if any of the components change

Mixes registered as General should only be used unless advice is sought from Technical Consulting.

Database contains commercially sensitive information and should not be distributed.

4. Asphalt Production

Batch Plant

Figure from Austroads ‘Asphalt Guide, 2002’

4. Asphalt Production

Drum Plant

Figure from Austroads ‘Asphalt Guide, 2002’

Mobile Drum Mixing Plant

Binder Storage Tanks

Cold Feed Storage Bins

Mechanical Sampling Device

Asphalt Laboratory

Solvent Extraction

Ignition Oven

5. Treatment SelectionWearing Courses

DGA Type L very lightly trafficked pavements, <500AADT

DGA Type N light to medium duty, <3000AADT

DGA Type H heavy duty, >3000AADT

DGA Type HP heavy duty, cracked area >3000AADT

DGA Type V signalised intersections, roundabouts, >5000AADT

5. Treatment SelectionWearing Courses

SMA improved crack resistance, high texture, rut resistance

SMAN for midblock, SMAH for intersections

OGA reduced water spray and noise, high texture

high speed facilities, multiple lanes

UTA increased texture, flexible, shorter service life

Blackburn Road, midblock, 60kph,

medium traffic, low HV

Stud Road, intersection, 80kph,

heavy traffic, 10% HV

Westernport Highway, roundabout, 80kph,


Holland Road, roundabout, 50kph, low traffic, low HV

FGR, midblock, 80kph, heavy traffic,

15% HV

Sesame St, midblock, 60kph, low traffic, low HV

Eastern Fwy, midblock, 100kph,


DVH, midblock, 70kph, medium traffic, high HV

Westernport Hwy Road, midblock, 100kph, medium traffic, high HV

References

Austroads/AAPA Work Tips (www.aapa.asn.au)

APRG Technical Notes

VicRoads Technical Notes

Austroads – Pavement Technology Series – 4B: Asphalt

Australian Standards

VicRoads, Standard Specification for Roadworks and Bridgeworks

http://www.aapa.asn.au/

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