Slide 1 of 34 By Shahin Shabani Transportation Research Institute (TRI) Tehran- Iran Presented on May 16 3 rd International Road Surface Friction conference Safer Road Surface – Saving lives Effect of Aggregate Arrangement on Increasing frictional Resistance Through Blending of Stone Material

Slide 2 of 34 Slide 1 of 18 Presentation Outline 2011/05/16 oIntroduction oProblem Statement and Main Objectives oGeneral Work Plan oExperimental Procedure oPreparation of Specimens oTesting Process oResults and Discussion oConclusions

Slide 3 of 34 Slide 2 of /05/16 Introduction Factor 1 Factor 2 Factor 3 Factor i Surface Characteristics MacrotextureMacrotexture MicrotextureMicrotexture

Slide 4 of 34 Slide 3 of /05/16 MicrotextureMicrotexture: function of surface texture of aggregate particles MicrotextureMicrotexture is Polished under traffic action Introduction Polishing Loss of Microtexture

Slide 5 of 34 Slide 5 of /05/16  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

Slide 6 of 34 Slide 6 of 18 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

Slide 7 of 34 Slide 6 of 18 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).

Slide 8 of 34 Slide 7 of 18 Mechanism of Polishing Two mechanism can occur during an aggregate polishing process: A general polishing, which tends to remove materials A general polishing, which tends to remove materials A differential polishing, which tend to create relief between soft and hard minerals. A differential polishing, which tend to create relief between soft and hard minerals. 2011/05/16

Slide 9 of 34 Slide 8 of 18 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

Slide 10 of 34 Slide 9 of 18 DescriptionDesignationDescriptionDesignation Longitudinal Group Regular arrangement D Transverse Group Regular arrangement A Longitudinal Non group Regular arrangement E Transverse Alternate Non group Regular arrangement B Irregular Random F Transverse Alternate Non group Regular arrangement C 2011/05/16 Experimental Procedure Preparation of specimens

Slide 11 of 34 Slide 10 of /05/16 Experimental Procedure Preparation of specimens

Slide 12 of 34 Slide 7 of 50Slide 11 of /05/16 Experimental Procedure Preparation of specimens

Slide 13 of 34 Slide 12 of /05/16 Experimental Procedure Testing Procedure

Slide 14 of 34 Experimental Procedure Testing Procedure

Slide 15 of 34 Slide 14 of 18 Results and Discussion PSV for different specimens 2011/05/16

Slide 16 of 34 Slide 14 of 18 Results and Discussion PSV for different specimens 2011/05/16

Slide 17 of 34 Slide 15 of /05/16 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.

Slide 18 of 34 Slide 16 of /05/16 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.

Slide 19 of 34 Slide 17of /05/16 Acknowledgements  Friends who helped during this research  Sponsors of this research Iran University of Science and Technology (IUST) Transportation Research Institute (TRI)

Slide 20 of 34 Slide 18 of /05/16 Thank you for your attention