Optical Sizing and Roundness Determination of Glass Beads Used in Traffic Markings (2010)

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Web-Only Document 156: Optical Sizing and Roundness Determination of Glass Beads Used in Traffic Markings National Cooperative Highway Research Program Haleh Azari AASHTO Materials Reference Library Gaithersburg, MD Edward Garboczi National Institute of Standards and Technology Gaithersburg, MD Contractor’s Final Report and Appendices A through I for NCHRP Project 20-07, Task 243 Submitted March 2010 NCHRP

ACKNOWLEDGMENT This work was sponsored by the American Association of State Highway and Transportation Officials (AASHTO), in cooperation with the Federal Highway Administration, and was conducted in the National Cooperative Highway Research Program (NCHRP), which is administered by the Transportation Research Board (TRB) of the National Academies. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, Transit Development Corporation, or AOC endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP. DISCLAIMER The opinions and conclusions expressed or implied in this report are those of the researchers who performed the research. They are not necessarily those of the Transportation Research Board, the National Research Council, or the program sponsors. The information contained in this document was taken directly from the submission of the author(s). This material has not been edited by TRB.

CONTENTS ABSTRACT ACKNOWLEDGMENTS  CHAPTER 1- INTRODUCTION AND RESEARCH APPROACH  1.1  Background  1.2  Problem Statement  1.3  Research Objectives  1.4  Scope of Study  CHAPTER 2- DESIGN AND CONDUCT OF THE ILS  2.1  Materials Selection  2.2  Sample Preparation  2.3  Methods of Testing Used in ILS  2.4  Participating Laboratories  2.5  Instructions for Interlaboratory Study  CHAPTER 3- INTERLABORATORY TEST RESULTS AND ANALYSIS  3.1  Test Data  3.2  Method of Analysis  3.3  Analysis of Results from Traditional Methods  3.3.1  Size Measurements Using Mechanical Sieve  3.3.1.1  Type 1 Samples  3.3.1.2  Type 3 Samples  3.3.1.3  Type 5 Samples  3.3.1.4  Summary of Percent Retained by Mechanical Sieve  3.3.2  Roundness Measurements Using Roundometer  3.3.2.1  Type 1 Samples 

ii 3.3.2.2  Type 3 Samples  3.3.2.3  Type 5 Samples  3.3.2.4  Summary of Percent Round by Roundometer  3.4  Analysis of Results from COM-A  3.4.1  Size Measurements  3.4.1.1  Type 1 Samples  3.4.1.2  Type 3 Samples  3.4.1.3  Type 5 Samples  3.4.1.4  Summary of Percent Retained by COM-A  3.4.2  Roundness Measurements Using SPHT Parameter  3.4.2.1  Type 1 Samples  3.4.2.2  Type 3 Samples  3.4.2.3  Type 5 Samples  3.4.2.4  Summary of Percent Round by COM-A SPHT  3.4.3  Roundness Measurements Using b/l Parameter  3.4.3.1  Type 1 Samples  3.4.3.2  Type 3 Samples  3.4.3.3  Type 5 Samples  3.4.3.4  Summary of Percent Round by COM-A b/l  3.4.4  D10, D50, and D90 Measurements  3.4.4.1  Type 1 Samples  3.4.4.2  Type 3 Samples  3.4.4.3  Type 5 Samples  3.4.4.4  Summary of D10, D50, and D90 Measurements by COM-A  3.5  Analysis of Results from COM-B 

iii 3.5.1  Size Measurements  3.5.1.1  Type 1 Samples  3.5.1.2  Type 3 Samples  3.5.1.3  Type 5 Samples  3.5.1.4  Summary of Percent Retained by COM-B  3.5.2  Roundness Measurements  3.5.2.1  Type 1 Samples  3.5.2.2  Type 3 Samples  3.5.2.3  Type 5 Samples  3.5.2.4  Summary of Percent Round by COM-B  3.5.3  D10, D50, and D90 Measurements  3.5.3.1  Type 1 Samples  3.5.3.2  Type 3 Samples  3.5.3.3  Type 5 Samples  3.5.3.4  Summary of D10, D50, and D90 Measurements by COM-B  3.6  Comparison of Precision Estimates of Various Measurement Methods  3.6.1  Size Measurements  3.6.1.1  Type 1 Samples  3.6.1.2  Type 3 Samples  3.6.1.3  Type 5 Samples  3.6.1.4  Summary of Precision in Size Measurement  3.6.2  Roundness Measurements  3.6.2.1  Type 1 Samples  3.6.2.2  Type 3 Samples  3.6.2.3  Type 5 Samples 

iv 3.6.2.4  Summary of Precision in Roundness Measurement  3.7  Comparison of Bias of Various Measurement Methods  3.7.1  Size Measurements  3.7.1.1  Type 1 Samples  3.7.1.2  Type 3 Samples  3.7.1.3  Type 5 Samples  3.7.1.4  Summary of Bias in Size Measurement  3.7.2  Roundness Measurements  3.7.2.1  Type 1 Samples  3.7.2.2  Type 3 Samples  3.7.2.3  Type 5 Samples  3.7.2.4  Summary of Bias in Roundness Measurement  CHAPTER 4- X-RAY TOMOGRAPHY SCANS OF THE GLASS BEADS  4.1  Introduction  4.2  Description of X-ray CT  4.3  X-ray CT Sample Preparation  4.4  Spherical Harmonics  4.5  Shape (Roundness) Analysis in 2-D  4.6  Exact Results for 2-D Shapes  4.7  Shape (Roundness) Analysis in 3-D  4.8  Comparison with Mechanical Sieve Analysis  4.9  Shape Results  4.10  Dependence of Roundness Cutoff on Particle Size (Sieve Class)   4.11  Further Comparison of 2-D vs. 3-D Shape Parameters  4.12  Images of Non-Round Particles for Different Samples