slide 1 of 34 by shahin shabani transportation research institute (tri) tehran- iran presented on...

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ByShahin Shabani

Transportation Research Institute (TRI)Tehran- Iran

Presented on May 16

3rd International Road Surface Friction conferenceSafer Road Surface – Saving lives

Effect of Aggregate Arrangement onIncreasing frictional Resistance Through

Blending of Stone Material

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Presentation Outline

2011/05/16

o Introductiono Problem Statement and Main Objectiveso General Work Plano Experimental Procedure

o Preparation of Specimenso Testing Process

o Results and Discussiono Conclusions

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Introduction

Road Surface

Friction

Factor 1

Factor 2Factor 3 Factor i

Surface Characteristics

Macrotexture Microtexture

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• Microtexture: function of surface texture of aggregate particles

• Microtexture is Polished under traffic action

Introduction

Polishing

Loss of Microtexture

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The ability of different aggregates to resist polishing is measured by PSV index in Lab

Standard BS EN 1097

There are 3 Categories of Aggregates:HPA (PSV≥60)MPA (50≤PSV<60)LPA (PSV<50)

Introduction

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Problem Statement and Main Objectives

2011/05/16

The most common rocks being used for road construction are the carbonate rocks

This group of rocks has low hardness and resistance to abrasion and polishing

carbonate aggregates are among LPA

The usage of LPA must be limited in the wearing surfaces

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Problem Statement and Main Objectives

2011/05/16

One way to improve would be in blending two or more types of aggregates with different PSV’s.

Research objective:Finding the best arrangement of two aggregates for achieving the maximum skidding resistance

in the laboratory scale.

Aggregate blending was studied in great detail by Ohio Department of Transportation(Liang 2003).

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Mechanism of Polishing

Two mechanism can occur during an aggregate polishing process:

A general polishing, which tends to remove materials

A differential polishing, which tend to create relief between soft and hard minerals.

2011/05/16

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General Work Plan

Collection of Limestone Aggregate

Collection of Basalt Aggregate

Preparation of Aggregates for polishing test

Preparation of test specimens for mounting on the APM ( 50/50 blend of Limestone and Basalt)

Accelerated Polishing of Aggregates Using the APM

Measurement of Friction Number Using the British Pendulum Tester

Determination of PSV Standard BS EN1097

Conclusions and Recommendations

2011/05/16

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A B C D E F Lime Stone Basalt

Description Designation Description DesignationLongitudinal

GroupRegular arrangement

DTransverse

GroupRegular arrangement

A

LongitudinalNon group

Regular arrangementE

TransverseAlternate

Non groupRegular arrangement

B

Irregular

RandomF

TransverseAlternate

Non groupRegular arrangement

C

2011/05/16

Experimental ProcedurePreparation of specimens

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(1) (2) (3) (4)

(5) (6) (7) (8)


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A B C D E F Lime Stone Basalt


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Experimental ProcedureTesting Procedure

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Experimental ProcedureTesting Procedure

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Results and DiscussionPSV for different specimens

2011/05/16

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Summery and Conclusions

Aggregate arrangement affects friction resistance; the highest change in PSV (about 7 units) has been obtained in this blending.

Transversal alternative arrangement of aggregates provides a better condition for the creation of a new texture.

The least friction is obtained when aggregates are placed in the specimens irregularly and randomly; this is usually the case.

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Summery and Conclusions

The best aggregate blending arrangement, with a different abrasion property, is achieved when aggregates are arranged regularly and also the conditions have been provided for the creation of a new texture.

The least friction reduction, during the test period, has been found from specimens with alternative non group regular arrangements.

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Acknowledgements

Friends who helped during this research

Sponsors of this research

Iran University of Science and Technology (IUST)

Transportation Research Institute (TRI)

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Thank you for your attention

slide 1 of 34 by shahin shabani transportation research institute (tri) tehran- iran presented on...

Documents

psv index

categories of aggregates

lab standard bs en

hpa psv60mpa