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Table 2 Percent retained of round and non-round glass beads for each sample type Sieve U.S. Type 1 (Y) Type 3 (P) Type 5 (C) Opening Sieve Size Round Non-Round Round Non-Round Round Non-Round 2000 #10 1700 #12 4.5% 0.5% 1400 #14 49.5% 5.5% 1180 #16 4.0% 1.0% 31.5% 3.5% 1000 #18 44.0% 11.0% 4.5% 0.5% 850 #20 28.0% 7.0% 710 #25 4.0% 1.0% 600 #30 3.5% 1.5% 500 #50 42.0% 18.0% 425 #100 24.5% 10.5% gradation (percent passing) of the three blends and laboratories returned results using mechanical sieving, Table 2 on their roundness, which includes percent eight laboratories returned results using COM-A, and retained round and non-round beads in each size class. four laboratories returned results using COM-B. Specimen sets were sent to 30 participating labo- ratories for property measurements. Depending on ILS Instructions the measurement capability of each laboratory or its willingness to conduct both mechanical and comput- Instructions for performing the tests and collecting erized methods, some laboratories received more than data were provided to each participant. The laborato- one specimen set. ries conducting the mechanical measurements were requested to follow the instructions prepared accord- ing to ASTM D1214 and D1155 and report the mea- Test Methods Evaluated in the ILS sured retained weights and the corresponding percent- Participating laboratories were asked to conduct ages of round and non-round glass beads in specified traditional sieve and roundometer tests, computerized size classes. The laboratories using the computerized optical methods, or both. The traditional methods optical method were requested to follow instructions followed ASTM D1214, "Sieve Analysis of Glass prepared with the help of the COM-A and COM-B Spheres" and ASTM D1155, "Roundness of Glass manufacturers. Participants using the computerized Sphere" test methods. Two types of computerized optical method equipment measured percent retained optical scanning instruments were used, denoted and percent round in each size class of each sam- COM-A and COM-B. One set of Type 1 samples was ple type in terms of the specific parameters of the also tested by a second type of COM-B device, which COM-A and COM-B instruments as presented in operates exactly in the same way as the other COM-B Table 3 and Table 4. The ILS instructions are available devices, so that their results in this report are both in Appendix A of the project final report. referred to as COM-B and were combined in the pre- cision and bias analysis for the Type 1 samples. ILS TEST RESULTS AND ANALYSIS Participating Laboratories Test Results State department of transportation (DOT) lab- Of the 30 sets of glass beads that were distributed oratories and glass bead and equipment manufactur- to the laboratories, 27 sets of results were received. ers and distributors were invited to participate in the Fifteen laboratories submitted full sets of size distri- ILS. Thirty laboratories responded to the invitation; 15 bution data using sieve analysis. Ten laboratories 3