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9 Table 3. Features and consideration of test methods for experimental evaluation. Direct (D) or Indirect Features of Consideration for Further Experimental Test Method (I) Analysis Concept Evaluation Method Uncompacted Void Content of I Yes Fine Aggregates AASHTO T304 Uncompacted Void Content of Packing of aggregate that flows Coarse Aggregates AASHTO I Yes through a given sized orifice TP56 Rugosity I No Time Index I No Index for Particle Shape and Packing of aggregate in a mold I No Texture ASTM D3398 using two levels of compactions Compacted Aggregate Resistance I Yes CAR Exposing a compacted specimen Florida Bearing Ra tio I No to pressure or shear forces Angle of Internal Friction from I No Direct Shear Test Percentage of Fractured Particles in Coarse Aggregate ASTM D Visual inspection of particles Yes D5821 Flat and Elongated Coarse D Measuring particle dimension Yes Aggregates ASTM D4791 using caliper Multiple Ratio Shape Analysis D Yes VDG-40 Videogra d er D Yes Using one camera to image and Computer Particle Analyzer D No evaluate particles in the sample Micromeritics OptiSizer PSDA D No as they fall in front of a Video Imaging System (VIS) D backlight No Buffalo Wire Works PSSDA D Yes Uses two cameras to image and evaluate particles in the sample Camsizer D Yes as they fall in front of a back light Uses two cameras to capture WipShape D image of aggregates passing on a Yes mini conveyor system Uses three cameras to capture University of Illinois Aggregate D three projections of a particle Yes Image Analyzer (UIAIA) moving on a conveyor belt Uses one camera and autofocus Aggregate Imaging System microscope to measure the D Yes (AIMS) characteristics of coarse and fine aggregates Laser-Based Aggregate Analysis D Uses a laser scan Yes System computation of the volume of each aggregate particle and uation, it was not available to this study during the experi- provides information about the actual 3-D characteristics of mental evaluation period. the aggregate. AIMS uses one video camera and a microscope to capture different types of images based on the type of aggregate and Aggregate Selection the property to be measured. The system measures the three This section includes a description of the aggregates that were dimensions of the aggregate particles. Images can be captured selected and used to evaluate the testing methods presented using different resolutions based on the particle size detected in Table 3. Aggregates were selected to cover a range of origin, by the system. The system is reported to analyze the charac- rock type, and characteristics. The thirteen coarse aggregates teristics of fine and coarse aggregates and provide a detailed and five fine aggregates described in Table 4 were used in this analysis of texture for coarse aggregates. study. Three coarse sizes and three fine sizes were used to per- LASS uses a laser scan to determine particles' shape and form the evaluation (see Table 4). Experienced individuals from angularity; although this system was selected initially for eval- the industry and highway agencies assisted in selecting and
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10 Table 4. Aggregate sources and sizes. Aggregate Sizes 25.4 - 12.5 - 9.5 - 4.75 - 2.36 - 0.6 - Aggregate 19.0 9.5 4.75 2.36 1.18 0.3 Label Source Description mm mm mm mm mm mm (1- (1/2- (3/8"- (#4 - (#8 - (#30 - 3/4") 3/8") #4) #8) #16) #60) Uncrushed Montgomery 1 River Gravel and X X X X X X AL Sand Crushed Montgomery 2 River Gravel and X X X X X X AL Sand Childersburg 3 Limestone X X X AL Auburn 4 Dolomite X X X AL Birmingham 5 Slag X X X X X X AL Brownwood 6 Limestone X X X X X X TX Fairfield Crushed Glacial 7 X X X OH Gravel Fairfield Uncrushed 8 X X X OH Glacial Gravel Forsyth 9 Granite X X X GA Ruby 10 Granite X X X X X X GA Knippa 11 Traprock X X X TX San Antonio 12 Limestone X X X TX Augusta 13 Granite X X X GA providing these aggregates (pictures of representative samples reduced to smaller samples, and washed according to ASTM are provided in Appendix E). and AASHTO standard procedures. Mineralogical content of the thirteen aggregates was deter- The same sample used in the nondestructive tests was used mined using X-ray diffraction (XRD)--a technique that uses by all operators and for all test replicates. Each sample of a X-rays of a single wavelength for establishing the structures coarse aggregate size was 1 kg, while each sample of a fine aggre- of crystalline solids. The sample analyzed was in a powder gate was 0.5 kg. In conducting the tests, the operators were form, consisting of fine grains of single crystalline material. asked to return the aggregates to the sample after running each Aggregates of the size 9.5 to 4.75 mm (3/8 to sieve #4) were test, and mix the sample before running the following test ground to a powder form (smaller than 0.075 mm and passes using the same method or a different method. sieve #200). A few grams of the powder sample was placed in a holder, and then the sample was illuminated with X-rays of Table 5. Mineralogical content of aggregates. a fixed wave length in the diffractometer. The intensity of the reflected radiation was recorded. These data were then analyzed Aggregate Aggregate Description Minerals Present Uncrushed River Gravel Quartz, Dolomite (trace) for the reflection angle to calculate the interatomic spacing 1 and Sand (d-value in angstrom units of 10-7 cm). The intensity was mea- 2 Crushed Quartz River Gravel and Sand sured to discriminate the various d-spacing, and the results 3 Limestone Calcite, Dolomite, Quartz were compared to specific tables to identify possible matches 4 Dolomite Dolomite 5 Slag Akermanite, Calcite, Quartz with mineral phases. The mineralogical content of the aggre- 6 Limestone Calcite, Quartz, Dolomite gates used in this study is presented in Table 5. 7 Crushed Glacial Gravel Dolomite, Calcite, Quartz 8 Uncrushed Glacial Gravel Dolomite, Calcite, Quartz The ASTM C 702 test procedure was followed to obtain rep- 9 Granite Quartz, Biotite, Albite, Labradorite Quartz, Chlorite, Albite, Amesite, Anorthite, resentative aggregate samples. Randomization was employed in 10 Granite Phlogophite (Mica), Muscovite dividing the aggregate into smaller representative samples to 11 Traprock Tephrite, Diopside, Augite, Anorthite 12 Limestone Calcite reduce bias due to unforeseen factors that would affect mea- Quartz, Albite, Calcite, Anorthite, 13 Granite surements. Aggregates selected for evaluation were sieved, Microcline, Kaolinite