Supporting Materials for NCHRP Report 673 (2011) / Chapter Skim
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From page 207... ...
F-2 TUTORIAL This self-study document is meant to familiarize technicians and engineers with the most important parts of the Manual and with the HMA Tools spreadsheet. The first part of this tutorial covers Chapters 3, 4, and 5 of the manual, which cover asphalt binders, aggregates, and volumetric composition, respectively.
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F-3 Chapter 3. Asphalt Binders After studying Chapter 3 of the manual, answer the questions below.
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F-4 Chapter 3. Asphalt Binders Solutions 1.
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F-5 Chapter 4. Aggregates After studying Chapter 4 of the manual, answer the questions below.
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F-6 5. The following test data was gathered during a specific gravity determination on a coarse aggregate sample: Dry weight of aggregate in air: 2,307.7 g Weight of saturated, surface-dry aggregate in air: 2,315.2 g Weight of aggregate in water: 1,432.6 g What is the bulk specific gravity of this aggregate?
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F-7 Chapter 4. Aggregates Solutions 1.
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F-8 4. What are typical specific gravity values for the following aggregates: diabase, limestone, sandstone, basalt?
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F-9 Chapter 5. Mixture Volumetric Composition After studying Chapter 5 of the manual, answer the questions below.
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F-10 Chapter 5. Mixture Volumetric Composition Solutions 1.
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F-11 Chapters 8 and 9: Dense-Graded HMA Mix Design Example Please read through Chapters 8 and 9 of the Mix Design Manual and then work through this example mix design, which will take you through most of the steps of a typical HMA mix design. You should work through the problem using the HMA Tools spreadsheet, if possible.
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F-12 GENERAL INFORMATION Date (mm/dd/yyyy) : 1/19/2009 Project: Tutorial Tech./Engr.: J
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F-13 Enter Aggregate Gradation, Specific Gravity and Specification Propery Values The table below lists aggregate gradation data, specific gravity values and specification property data for four aggregates that will be used in this example mix design. Use this information to complete the "Aggregates" worksheet in HMA Tools.
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F-14 AGGREGATE PROPERTIES Help Appears Below Aggregate Name/Code Coarse 1 Coarse 2 Coarse 3 Mfg. Fines Bulk Spec.
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F-15 Calculate Average RAP properties and Maximum Allowable RAP Content Based on Variability. Standards and specification for designing HMA mixtures containing RAP vary widely among different agencies.
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F-16 RAP STATISTICS ANALYSIS OF RAP VARIABILITY AND ESTIMATED MAXIMUM RAP CONTENT 80.0 100 31 Enter in cell D28 on Worksheet General SAMPLE NUMBER: 1 2 3 4 5 6 7 8 9 10 11 Average Std.
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F-17 Enter RAP Aggregate Data Enter the average RAP aggregate gradation calculated in the previous step (cells A19:A31 of worksheet "RAP_Variability") in worksheet "RAP_Aggregates" in cells C31:C43.
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F-18 RAP Aggregates RAP 1 RAP 2 RAP 3 RAP4 Description: RSP No. 18 Binder Content, Wt.
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F-19 Enter Grading Data for New Binder When more than 15% RAP is used in a mix design, you must enter grading data for one or more new asphalt binders (HMA Tools allows you to enter data for up to four different new binders and binders from up to four RAP stockpiles)
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F-20 BINDERS Grade: Producer/Description: Specific Gravity 1.024 Unaged Binder Temp.
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F-21 Enter Grading Data for RAP Binder Now, enter the data below on the grading of the recovered RAP binder in worksheet "RAP_Binders." Again, remember that you don't need this information if you are using less than 15% RAP in your mix design. The specific gravity of the binder is 1.03.
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F-22 RAP BINDERS Specific Gravity 1.030 Unaged Binder Temp.
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F-23 Develop Aggregate Blends for Three Trial Mixes HMA Tools makes it easy to develop aggregate blends for trial mixes. Go to worksheet "Trial_Blends." Aggregate blends are developed by entering aggregate blend data -- in percentage by weight -- in cells F25:L36.
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F-24 As you develop your trial blends, look through worksheet "Trial_Blends" and try to make sure all or most requirements are given. However, most volumetric information won't be given, since it cannot be calculated until bulk and maximum specific gravity tests are performed on the trial mixes and the resulting data entered in HMA Tools.
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F-25 TRIAL AGGREGATE BLENDS help appears at lower right INCLUDE MAX.
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F-26 Comments on Trial Blends Because of the size of the "Trial_Blends" worksheet, only part of the worksheet is shown above. Again, remember that your three trial blends may not look the same as the ones given above.
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F-27 Calculate Batch Weights for Gyratory Specimens To complete the evaluation of the trial mixes, trial batches must be prepared and gyratory specimens compacted. When preparing trial batches, aggregate stockpiles are usually broken down into different fractions and weighed out separately.
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F-28 BATCHING REPORT Trial Batch No.: 2 Cylinders: Dia., mm Ht., mm No. Date (mm/dd/yyyy)
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F-29 Specific Gravity Measurements In order to complete the evaluation of the trial mixes, the specific gravity of the mixes -- both the theoretical maximum specific gravity values of loose mix and the bulk specific gravity of the compacted specimens -- are measured. Data from specific gravity measurements are entered in worksheet "Specific_Gravity." In this worksheet, you can either enter raw data from the measurements and have HMA Tools calculate the specific gravity values, or you can just enter the correct specific gravity values without the raw data -- this would happen, for instance, if your laboratory has its own forms for recording specific gravity measurements and does not want to use HMA Tools for this purpose.
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F-30 SPECIFIC GRAVITY CALCULATIONS BULK SPECIFIC GRAVITY Weight in Water/SSD Method 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 Dry mass in air, g, A 4683.0 4746.3 SSD mass in air, g, B 4695.2 4751.8 Mass in water, g, C 2697.0 2743.7 Water absorption, Wt.
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F-31 SPECIFIC GRAVITY CALCULATIONS (continued from previous page) User-Calculated Value Theoretical maximum specific gravity 2.462 2.463 USE THEORETICAL MAXIMUM SPECIFIC GRAVITY 2.467 2.462 2.463 VOLUMETRIC ANALYSIS Aggregate bulk specific gravity, dry basis 2.645 2.642 2.639 Air void content, % by volume 4.6 3.4 3.9 Asphalt content, % by weight 5.13 5.10 5.10 Aggregate content, % by weight 94.87 94.90 94.90 VMA, % by volume 15.6 14.6 14.9 Vbe, % by volume 11.0 11.2 11.0 Calculated Agg.
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F-32 TRIAL AGGREGATE BLENDS help appears at lower right INCLUDE MAX.
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F-33 Evaluating and Refining Trial Mixtures After mixing, compacting, and analyzing the volumetric composition of the three trial mixtures, the specification requirements of each should be analyzed. This is best done by reviewing information on the worksheet "Trial_Blends." But remember, specific gravity testing must first be performed on the trial mixtures and entered into worksheet "Specific_Gravity." Check the various specification requirements on all there trial mixtures.
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F-34 The table below summarizes all the various requirements for this HMA mix design. All three trial mixes meet most of the requirements, but mixes 1 and 2 fail the air void requirement of 3.5 to 4.5% (the air void content of mix 1 is too high, while the air void content of mix 2 is slightly low)
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F-35 Moisture Resistance Testing (AASHTO T 283) Just as in Superpave, one of the last steps in the mix design is performing moisture resistance testing following AASHTO T283.
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F-36 AASHTO T 283 Project: Tutorial Trial Blend Number: 1 Additive: None Additive Dosage: Compaction Method: Gyratory Compaction Effort: 75 Date Tested: 10/30/2009 Tested by: J Doe 1 2 3 4 5 6 7 8 Diameter, mm (in.)
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F-37 Performance Testing In the Superpave mix design method, there is no performance or "proof" test after completing a volumetric mix design. In the mix design procedure described in this manual, HMA mix designs intended for traffic levels of 3,000,000 ESALs or greater must be evaluated for rut resistance using one of six performance tests: • Asphalt mixture performance test (AMPT)
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F-38 Printing a Report on a Mix Design Once you have completed a mix design, or if you want to summarize one or more trial mixes, you can use HMA Tools to print out a report. Go to worksheet "Short_Report," and fill out the date in cell D4, and place "3" in cell D5, meaning you want to generate a report for trial mix No.
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F-39 SHORT REPORT ON HMA MIX DESIGN Material Gsb Gsa Wt. % MIXTURE VOLUMETRIC PROPERTIES 2.704 2.742 11.4 2.680 2.735 11.4 Specifications Value 2.628 2.713 24.7 Voids 3.5 to 4.5 3.9 2.666 2.737 19.0 VMA 14 to 16.0 14.9 #N/A #N/A 0.0 Dust/Binder 0.8 to 1.6 1.1 #N/A #N/A 0.0 #N/A #N/A 0.0 Vbe NA 11.0 #N/A #N/A 0.0 VFA NA 73.8 2.590 2.624 28.5 #N/A #N/A 0.0 #N/A #N/A 0.0 #N/A #N/A 0.0 5.10 Required Asphalt Binder Grade: 4.07 Blended Asphalt Binder Grade: Aggregate Blend Effective Specfic Gravity: 2.664 New Asphalt Binder Grade: AGGREGATE GRADATION OTHER AGGREGATE PROPERTIES Sieve Size, mm Min.
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F-40 Other Chapters in the Mix Design Manual Congratulations! You have completed the tutorial.
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