Refining the Simple Performance Tester for Use in Routine Practice (2008) / Chapter Skim
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From page 39... ...
39 A P P E N D I X A Proposed Standard Practices
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• NCHRP 9-29 PT 01, Determining the Dynamic Modulus and Flow Number for Hot Mix Asphalt (HMA) Using the Simple Performance Test System 2.2 Other Publications • Equipment Specification for the Simple Performance Test System, Version 3.0, Prepared for National Cooperative Highway Research Program (NCHRP)
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6. APPARATUS 6.1 Specimen Fabrication Equipment - Equipment for fabricating dynamic modulus test specimens as described in NCHRP 9-29 PP 01, Preparation of Cylindrical Performance Test Specimens Using the Superpave Gyratory Compactor.
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9. DYNAMIC MODULUS TEST DATA 9.1 Test Specimen Fabrication 9.1.1 Prepare at least two test specimens to the target air void content and aging condition in accordance with NCHRP 9-29 PP 01, Preparation of Cylindrical Performance Test Specimens Using the Superpave Gyratory Compactor.
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If a dynamic modulus test system other than the Simple Performance Test System is used, refer to Equipment Specification for the Simple Performance Test System, Version 3.0 for algorithms for computation of dynamic modulus, phase angle, and data quality statistics. 9.3 Dynamic Modulus Data Summary 9.3.1 Prepare a summary table of the dynamic modulus data.
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⎟⎟⎠ ⎞ ⎜⎜⎝ ⎛ − Δ += r a r TT Eff 11 14714.19 loglog (2) where: fr = reduced frequency at the reference temperature, Hz f = loading frequency at the test temperature, Hz Average Modulus Average Std Dev Temperature Frequency Modulus Phase Angle Modulus Phase Angle Modulus Phase Angle Modulus CV Phase Phase C Hz Ksi Degree Ksi Degree Ksi Degree Ksi % Deg Deg 4 0.1 1170.9 18.8 1214.8 19.6 1443.2 18.5 1276.3 11.5 19.0 0.5 4 1 1660.8 12.0 1743.5 12.5 2027.0 11.6 1810.5 10.6 12.0 0.4 4 10 2107.3 8.1 2245.6 8.4 2596.1 8.2 2316.3 10.9 8.2 0.2 20 0.1 259.1 33.9 289.9 33.5 315.2 34.6 288.1 9.8 34.0 0.6 20 1 604.1 27.4 657.3 26.8 711.2 27.0 657.5 8.1 27.1 0.3 20 10 1065.1 21.0 1181.5 18.8 1231.4 19.8 1159.3 7.4 19.9 1.1 40 0.01 17.2 18.6 16.5 18.8 18.8 19.2 17.5 6.7 18.9 0.3 40 0.1 26.5 24.8 26.4 26.1 30.6 26.0 27.8 8.6 25.6 0.7 40 1 62.9 31.5 63.9 32.1 74.5 32.7 67.1 9.6 32.1 0.6 40 10 180.1 35.2 197.6 35.1 220.6 35.2 199.4 10.2 35.2 0.1 Conditions Specimen 1 Specimen 2 Specimen 3
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= shift factor at temperature T Tr = reference temperature, °K T = test temperature, °K ΔEa = activation energy (treated as a fitting parameter) 10.3 Limiting Maximum Modulus.
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10.4.1.2 Compute the logarithm of the limiting maximum modulus and designate this as Max 10.4.2 Step 2. Select a the Reference Temperature 10.4.2.1 Select the reference temperature for the dynamic modulus master curve and designate this as Tr.
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Sy = standard deviation of the logarithm of the average dynamic modulus values 10.5 Evaluate Fitted Master Curve 10.5.1 The ratio of Se to Sy should be less than 0.05 10.5.2 The explained variance should exceed 0.99 10.6 Determine AASHTO Mechanistic-Empirical Pavement Design Guide Inputs 10.6.1 Substitute the logarithm of the limiting maximum modulus (Max) determined in Section 10.4.1.2 and the fitting parameters (δ, β, γ, and ΔEa)
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11.10 Goodness of fit statistics for the fitted master curve (Se, Sy, Se/Sy, R2) 11.11 Plot of the fitted dynamic modulus master curve as a function of reduced frequency showing average measured dynamic modulus data 11.12 Plot of shift factors as a function of temperature 11.13 Plot of average phase angle as a function of reduced frequency.
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• T 166, Bulk Specific Gravity of Compacted Asphalt Mixtures Using Saturated Surface-Dry Specimens. • T 209, Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures.
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Using the Simple Performance Test System 5.2 This practice may also be used to prepare specimens for other non-standard tests requiring 100 mm diameter by 150 mm tall cylindrical test specimens.
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6.2 Mixture Preparation Equipment – Balances, ovens, thermometers, mixer, pans, and other miscellaneous equipment needed to prepare gyratory specimens in accordance with AASHTO T 312 and make specific gravity measurements in accordance with AASHTO T 166, T 209, and T 269. 6.3 Core Drill – An air or water cooled diamond bit core drill capable of cutting nominal 100 mm diameter cores meeting the dimensional requirements of Section 9.5.3.
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9.1.2 The mass of mixture needed for each specimen will depend on the gyratory specimen height, the specific gravity of the aggregate, the nominal maximum aggregate size and gradation (coarse or fine) , and the target air void content for the test specimens.
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9.4.3 For open-graded mixtures, determine the bulk specific gravity of the gyratory specimen in accordance with Section 6.2 of AASHTO T 269. 9.4.4 Compute the air void content of the gyratory specimen in accordance with AASHTO T 269.
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9.5.3 Test specimens shall meet the dimensional tolerances given in Table 1. Table 1.
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Record the bulk specific gravity of the test specimen. 9.6.4 Compute the air void content of the test specimen in accordance with AASHTO T 269.
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10.2 Mixture design number for link to pertinent mixture design data including design compaction level and air void content, asphalt binder type and grade, binder content, binder specific gravity, aggregate types and bulk specific gravitities, consensus aggregate properties, and maximum specific gravity. 10.3 Type of aging used.
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A2. SUMMARY A2.1 Trial test specimens are prepared as described in this standard practice from gyratory specimens produced with a standard mass of 6,650 g and compacted to a standard height of 170 mm.
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s t t Va Va W 5257175 −= (A1) where: Wt = estimated mass of mixture required to produce a gyratory specimen for a test specimen with a target air void content of Vat, g Vat = target air void content for the test specimen, vol % Vas = test specimen air void content produced with a gyratory mass of 6,650 g, vol % A3.5 Prepare trial test specimen 3 following this standard practice from a gyratory specimen produced with the target mass estimated in Section A3.4 and compacted to the standard height of 170 mm.
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7175( −= WSVa (A4) A4.5 If gyratory specimens are compacted using a standard mass, Ws, and the air void contents for the resulting test specimens are determined to be Vas, then Equation A4 can be solved for the slope.
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Vas = test specimen air void content produced with a gyratory mass of Ws, vol % Ws = mass of mixture used to produce the gyratory specimen
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B2.2 The test specimens are cut into three slices of equal thickness and the bulk specific gravity or each slice is determined. B2.3 A statistical hypothesis test is conducted to determine the significance of differences in the mean bulk specific gravity of the top and bottom slices relative to the middle.
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( 2 3 12 ∑ = − = i i yy s (B2) where: y = slice mean s 2 = slice variance yi = measured bulk specific gravities B3.6 Statistical Comparison of Means- Compare the mean bulk specific gravity of the top and bottom slices to the middle slice using the hypothesis tests described below.
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Null Hypothesis: The mean bulk specific gravity of the bottom slice equals the mean bulk specific gravity of the middle slice, 22 mb μμ = Alternative Hypothesis: The mean bulk specific gravity of the bottom slice is not equal the mean bulk specific gravity of the middle slice, 22 mb μμ ≠ Test Statistic: ( )
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64 B4.2 Specimens with differences for the top and/or bottom slices relative to the middle slices on the order of 0.025 have performed satisfactorily in the dynamic modulus, flow number, flow time, and continuum damage fatigue tests. B4.3 Changing the height of the gyratory specimen can improve the uniformity of the density in the test specimen.
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