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From page 8... ... also found that smaller coarse aggregate particles provided more aggregate interlocking and resulted in increased HMA shear strength. Accelerated pavement testing seems to delineate the effect of maximum aggregate size on HMA performance much more effectively than do the laboratory methods. Read the entire page →
From page 9... ... , as affected by particle shape, angularity, and surface texture, is determined in accordance with ASTM C 1252 by measuring the voids ratio of loosely placed fine aggregate in a standard cylinder. In general, fine aggregates with high FAA values result in higher internal friction and stronger bonds with asphalt binder that leads to better stability and rut resistance of HMA mixtures. Read the entire page →
From page 10... ... It was found that the higher the rugosity of the coarse aggregate, the larger the size of fine particles that result in higher HMA mixture shear strength. The amount of mineral filler used in HMA mixtures does not seem to affect rutting performance adversely as measured by the Repeated Shear at Constant Height (RSCH) Read the entire page →
From page 11... ... tests were performed on a standard specimen consisting of 750 g of 12.5-mm 11 Aggregate Type Dolomite Limestone Uncrushed Gravel Granite Traprock #78 Designation CA-1 CA-2 CA-3 CA-4 CA-5 Source Location Indiana Indiana Indiana North Carolina Virginia Nominal Maximum Size (mm) 12.5 12.5 12.5 12.5 12.5 Percent Passing 19.0 100 12.5 100 100 100 100 89.0 9.5 87.0 87.9 84.1 90.0 60.0 4.75 25.0 24.7 18.1 23.0 7.0 2.36 1.4 4.7 1.1 4.0 2.0 1.18 0.4 2.0 0.2 3.0 0.6 0.60 0.4 1.7 0.2 2.0 0.6 0.30 0.3 1.5 0.2 1.0 0.6 0.15 0.3 1.4 0.2 1.0 0.6 Si ev e Si ze (m m) Read the entire page →
From page 12... ... Field Results In addition to testing aggregate samples received from the producers for mixture design purposes, flat and/or elongated tests were conducted on aggregate samples taken from the HMA plant stockpiles, aggregate recovered from plant-produced mixtures, and aggregate recovered from APT test section cores after binder extractions. Table 7 lists the flat and/or elongated values of the coarse aggregates from these sources. Read the entire page →
From page 13... ... fine aggregates were not used in the study. Aggregate Type Natural Sand A Crushed Gravel Sand Natural Sand B Granite Sand Dolomite Sand1 Traprock #161 Designation FA-1 FA-2 FA-3 FA-4 FA-5 FA-6 Source Location Indiana Indiana Ohio North Carolina Indiana Virginia Percent Passing 9.5 100 100 100 100 100 100 4.75 100 100 100 99.0 98.4 95.0 2.36 89.9 81.8 85.3 83.0 71.6 57.0 1.18 59.2 50.6 61.9 57.0 31.7 34.0 0.60 30.4 30.8 37.5 40.0 15.0 20.0 0.30 9.0 17.2 18.0 27.0 6.0 12.0 0.15 1.6 7.3 6.1 19.0 1.7 6.0Si ev e Si ze (m m) Read the entire page →
From page 14... ... The bulk specific gravity and absorption values of the fine aggregates were determined according to the ASTM C 128 method. Field Results In addition to testing laboratory samples received from aggregate producers, aggregate samples collected from the HMA plant stockpiles and recovered from plant-produced mixtures and APT cores were also tested. Read the entire page →
From page 15... ... Fine-Graded Mixtures A natural uncrushed gravel with a UVA of 42.2 percent was used as the coarse aggregate for all fine-graded HMA mixtures 15 Mixture ID FA-1 FA-2 FA-3 FA-4 FA-5b FA-6b Aggregate Type Natural Sand A Crushed Gravel Sand Natural Sand B Granite Sand Dolomite Sand Traprock Sand Uncompacted Voids Content, % Mixture Design 40.3 46.1 41.9 49.1 46.8 49.2 HMA Plant Stockpile 39.2 47.6 42.0 48.9 46.2 49.3 HMA Plant Mixture 38.7 45.1 40.9 46.2 45.0 46.6 APT Cores 38.3 44.7 41.0 45.5 45.1 46.4 Methylene Blue Value Mixture Design 3.3 1.3 4.9 11.1 2.8 5.1 Sa m pl e So ur ce HMA Plant Stockpile 7.8 1.3 5.5 5.8 2.8 6.9 Table 9. Fine aggregate uncompacted voids content (Method A) Read the entire page →
From page 16... ... Moisture Susceptibility Mixtures Five of the six fine aggregates used in the rutting study were selected for the moisture susceptibility experiment. Each fine aggregate was combined with a common, crushed dolomite coarse aggregate and mixture designs were completed; mixture design data are given in Table 10. Read the entire page →
From page 17... ... Each test lane was trafficked until a total rut depth of 20 mm was achieved or 20,000 wheel passes were applied, whichever occurred first. Profiles were recorded at nine locations over the length of a given test section; however, three consecutive sections nearest the center of the test section (Sections 4, 5, and 6, see Figure D.8) Read the entire page →
From page 18... ... Table 14 lists total rut depths at 1,000; 5,000; and 20,000 wheel passes and rutting rates for both early and later traffic stages. These rutting parameters were used as the basis for ranking mixture performance from 1 (best) Read the entire page →
From page 19... ... Table 17 shows total rut depths for 1,000; 5,000; and 20,000 wheel passes and total rutting rates for early and later traffic stages. These rutting parameters were used in ranking performance. Read the entire page →
From page 20... ... Testing mixtures with the greatest range of aggregate quality, as determined by the aggregate test methods, were expected to provide the most useful information for determining the strength of the relationships between the aggregate properties and fatigue performance. 20 0 5 10 15 20 25 30 0 5000 10000 15000 20000 Number of Wheel Passes, N A ve ra ge T ot al R ut D ep th , m m FAM1 Natural Sand A, IN FAM2 Crushed Gravel Sand, IN FAM3 Granite Sand, NC FAM4 Traprock Sand, VA FAM5 Natural Sand B, OH Figure 8. Read the entire page →
From page 21... ... After subgrade compaction, a geotextile fabric was placed on the subgrade and an unbound, crushed stone base course was placed and compacted such that the finished base course was 200 mm in depth. The 100-mm deep HMA test section mixtures were then constructed on the base course using conventional HMA construction techniques as described in Appendix D (available in NCHRP Web-Only Document 82) Read the entire page →
From page 22... ... Subgrade failure was repaired and traffic continued; however, damage at the edge continued to accumulate and it was necessary to discontinue trafficking of the section to avoid damage to the APT equipment. The third mixture to undergo fatigue testing was the FA-1 mixture produced using Natural Sand A Read the entire page →
From page 23... ... FA-1 test section after 2,000 wheel passes. fatigue results of the last three APT test sections. Read the entire page →

From page 8...

... also found that smaller coarse aggregate particles provided more aggregate interlocking and resulted in increased HMA shear strength. Accelerated pavement testing seems to delineate the effect of maximum aggregate size on HMA performance much more effectively than do the laboratory methods.