1、Standard Method of Test for Determining the Fracture Energy Density of Asphalt Binder Using the Binder Fracture Energy (BFE) Test AASHTO Designation: TP 127-171Technical Section: 2b, Liquid Asphalt Release: Group 3 (August 2017) American Association of State Highway and Transportation Officials 444
2、North Capitol Street N.W., Suite 249 Washington, D.C. 20001 Standard Method of Test for Determining the Fracture Energy Density of Asphalt Binder Using the Binder Fracture Energy (BFE) Test AASHTO Designation: TP 127-171Technical Section: 2b, Liquid Asphalt Release: Group 3 (August 2017) 1. SCOPE 1.
3、1. This test method covers the determination of fracture energy density of asphalt binder by means of a direct tension test. For evaluation of relative cracking performance, it is recommended that this test procedure be used with asphalt binder aged using T 240 (RTFO) plus R 28 (PAV). However, this
4、test can be used for determination of binder facture energy for any binder including any aged (RTFO plus PAV or PAV only) neat or modified binder and asphalt binder extracted and recovered from pavement. The test apparatus is designed for testing within the intermediate temperature range, from 0C to
5、 25C. 1.2. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to establish appropriate safety and health practices and to determ
6、ine the applicability of regularity limitations prior to use. 2. REFERENCED STANDARDS 2.1. AASHTO Standards: M 320, Performance-Graded Asphalt Binder R 28, Accelerated Aging of Asphalt Binder Using a Pressurized Aging Vessel (PAV) R 49, Determination of Low-Temperature Performance Grade (PG) of Asph
7、alt Binders R 66, Sampling Asphalt Materials T 240, Effect of Heat and Air on a Moving Film of Asphalt Binder (Rolling Thin-Film Oven Test) 2.2. ASTM Standards: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials E1, Standard Specification
8、for ASTM Liquid-in-Glass Thermometers E4, Standard Practices for Force Verification of Testing Machines E77, Standard Test Method for Inspection and Verification of Thermometers E83, Standard Practice for Verification and Classification of Extensometer Systems 2.3. ISO Standard: 2017 by the American
9、 Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law. ISO 10012, Measurement Management SystemsRequirements for Measurement Processes and Measuring Equipment 3. TERMINOLOGY 3.1. Definition: 3.1.1. asphalt binderan asphalt-based
10、 cement that is produced from petroleum residue either with or without the addition of particulate organic modifiers of size less than 250 m. 3.2. Description of Terms Specific to This Standard: 3.2.1. brittletype of failure in a direct tension test where the stressstrain curve is essentially linear
11、 up to the point of failure and the failure is sudden by rupture of the test specimen without appreciable reduction in cross-sectional area of the specimen. 3.2.2. brittleductiletype of failure in a direct tension test where the stressstrain curve is curvilinear and the failure is by the rupture of
12、the test specimen. Limited reduction in the cross-section of the specimen occurs before rupture. 3.2.3. ductiletype of failure in a direct tension test where the specimen does not rupture but fails by flow at large strain. 3.2.4. failurefor specimens exhibiting a stressstrain curve with a single pea
13、k stress followed by a continuously increasing reduction in stress, failure is the point at which the tensile stress reaches a maximum value. 3.2.5. failure strainthe tensile strain corresponding to the failure stress. 3.2.6. failure stressthe tensile stress at the point associated with failure as d
14、efined in Section 3.2.4. 3.2.7. fracture energy densitymaximum energy that can be stored in a unit volume of material without the occurrence of fracture. 3.2.8. large strain formulationanalysis, which includes changes in geometry due to excessively large strain. 3.2.9. neckingdisproportionately larg
15、e strain localized in a small region of the asphalt binder specimen which results in a prominent decrease in local cross-sectional area. 3.2.10. tensile strainaxial strain resulting from the application of a tensile load and calculated as the change in length of the effective gauge length caused by
16、the application of the tensile load divided by the original unloaded effective gauge length. 3.2.11. tensile stressaxial stress resulting from the application of a tensile load and calculated as the tensile load divided by the original area of cross-section of the specimen. 3.2.12. true strainstrain
17、 determined by accounting for reduction in cross-sectional area. 3.2.13. true stressratio of the applied load to the instantaneous cross-sectional area. 3.2.14. true stresstrue strain curvegraphical representation of the relationship between true stress and true strain. 2017 by the American Associat
18、ion of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.4. SUMMARY OF TEST METHOD 4.1. This method describes the procedure used to measure stress and strain on a fracture failure plane in an asphalt binder specimen pulled at a constant rat
19、e of displacement (displacement-control). Test specimens have a special geometry (Figure 1) and they are prepared using the specified mold. Two G10 phenolic end tabs are bonded to the asphalt binder, and they transfer the tensile load from the test machine to the asphalt binder. 4.2. This test metho
20、d was developed for asphalt binders at intermediate temperatures where they exhibit brittleductile or brittle failure. The test is not applicable at temperature where failure is by ductile flow (necking). 4.3. A displacement transducer is used to measure the elongation of the test specimen as it is
21、pulled in tension at a designated displacement rate. The load developed during the test is also measured. The tensile stress and strain from initial loading through failure are determined and used to calculate and report failure stress, failure strain, and fracture energy density. 4.4. Fracture ener
22、gy density can be used to evaluate the relative resistance to fracture of different asphalt binders. In addition, characteristics of the resulting true stresstrue strain curve can be used to identify the presence of polymer and/or rubber in the binder. Notes: aAll dimensions are in millimeters (inch
23、es in parentheses.) bTolerances are as follows: Fractions 1.6 (0.0625) X.X 0.8 (0.03) X.XX 0.25 (0.01) X.XXX 0.12 (0.005) cRemove all sharp edges. dSurface finish for machined surfaces equals 125unless otherwise specified. Figure 1Specimen Geometry 2017 by the American Association of State Highway a
24、nd Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2b TP 127-4 AASHTO 5. SIGNIFICANCE AND USE 5.1. The test is designed to measure fracture energy density of asphalt binder at intermediate temperatures. Fracture energy density has been shown to be an in
25、dicator of the resistance to fracture of an asphalt binder. 5.2. The test can be used to differentiate unmodified and modified binders by means of either the characteristics of the true stresstrue strain curve or fracture energy density value. The test can also be used as an effective tool to screen
26、 new binders that may result in deficient performance. 5.3. For a given binder, fracture energy density as measured by this procedure has been determined to be independent of displacement rate and testing temperature. Although test temperatures may vary from 0C to 25C, 15C was found to work well for
27、 a broad range of binders. Therefore, this temperature was recommended to determine fracture energy density. 5.4. Although the test displacement rate may vary from 100 mm/min to 900 mm/min, 500 mm/min was found to work best for a broad range of binders. Therefore, this displacement rate is primarily
28、 used to determine binder fracture energy density at 15C. Test outcomes at the 500 mm/min rate may require an increase or decrease in this rate as specified in the test procedure, Section 11.3.1. 6. APPARATUS 6.1. A forced-air convection oven capable of reaching and maintaining 170 10C for heating a
29、sphalt. 6.2. A loading system capable of pulling a test specimen at constant loading rates ranging from 100 to 900 mm/min. 6.2.1. Test chamber for temperature control and testing, which is capable of maintaining a temperature between 0C to 25C, 0.2C. 6.2.2. Load cell capable of accurately measuring
30、tensile load up to 448 N (100 lb) with a resolution of 0.01 lb. 6.2.3. Linear variable differential transducer (LVDT) with a resolution of 0.000001 in. 6.2.4. Load measuring and recording devices (data acquisition system) capable of acquisition rates of up to 1,000 samples per second, per channel. 6
31、.3. Figure 2 illustrates a miniature loading frame with two (or more) parallel precision rods, which allows 1.2-in. travel length and applies an axial load minimizing any eccentricity to the BFE specimen. 6.4. Specimen mold assemblies. 6.4.1. Specimen molds shall be manufactured from aluminum, with
32、the exception of the end tabs. 6.4.2. The specimen molds include: 6.4.2.1. Two side plates (Figure 5a), 6.4.2.2. One bottom plate (Figure 5b), 6.4.2.3. Two G10 phenolic end tabs (Figure 6a), and 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Dupl
33、ication is a violation of applicable law.TS-2b TP 127-5 AASHTO 6.4.2.4. Metal rings (Figure 6b). 6.4.3. Binder clips (Figure 9). 6.4.4. Trim knife (Section 10.6). 6.5. Demolding gauge (Figure 7). 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Dup
34、lication is a violation of applicable law.Notes: aAll dimensions are in millimeters (inches in parentheses.) bTolerances are as follows: Fractions null1.6 (0.0625) X.X null0.8 (0.03) X.XX null0.25 (0.01) X.XXX null0.12 (0.005) Angles 30 degrees cSurface finish for machined surfaces equals 125unless
35、otherwise specified. dThread to accommodate load cell. eDrilled and reamed to dimention 0.5-in. frelon bearing or similar (Pacific bearing FL08). fMaterial: 300-series stainless steel or 6061-T6 aluminum. Figure 2Loading Frame Assemblies: Upper Loading Head 2017 by the American Association of State
36、Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.Figure 3Loading Frame Assemblies: Lower Loading Head 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable l
37、aw.Figure 4Loading Frame Assemblies: Base 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.a) Side Plate b) Bottom Plate Notes: aAll dimensions are in millimeters (inches in parentheses). bTolerances are
38、 as follows: Fractions 1.6 (0.0625) X.X 0.8 (0.03) X.XX 0.25 (0.01) X.XXX 0.12 (0.005) cSurface finish for machined surfaces equals 125unless otherwise specified. Figure 5Specimen Mold Components 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Dup
39、lication is a violation of applicable law.a) End Tab b) Insert Metal Ring Notes: aAll dimensions are in millimeters (inches in parentheses). bTolerances are as follows: Fractions 1.6 (0.0625) X.X 0.8 (0.03) X.XX 0.25 (0.01) X.XXX 0.12 (0.005) Angles 30 degrees cRemove all sharp edges. dSurface finis
40、h for machined surfaces equals 125unless otherwise specified. eMaterial: G10 phenolic. fSee also metal ring and assembly drawings. Notes: aAll dimensions are in millimeters (inches in parentheses). bTolerances are as follows: Fractions 1.6 (0.0625) X.X 0.8 (0.03) X.XX 0.25 (0.01) X.XXX 0.12 (0.005)
41、Angles 30 degrees cRemove all sharp edges. dSurface finish for machined surfaces equals 125unless otherwise specified. eMaterial: Stainless Steel Type 316 or 304. Figure 6End Tab and Insert Metal Ring for Binder Fracture Energy Test 2017 by the American Association of State Highway and Transportatio
42、n Officials. All rights reserved. Duplication is a violation of applicable law.a) Plate b) Pins Notes: aAll dimensions are in millimeters (inches in parentheses). bTolerances are as follows: Fractions 1.6 (0.0625) X.X 0.8 (0.03) X.XX 0.25 (0.01) X.XXX 0.12 (0.005) cSurface finish for machined surfac
43、es equals 125unless otherwise specified. Notes: aAll dimensions are in millimeters (inches in parentheses). bTolerances are as follows: Fractions 1.6 (0.0625) X.X 0.8 (0.03) X.XX 0.25 (0.01) X.XXX 0.12 (0.005) Angles 30 degrees cRemove all sharp edges. dSurface finish for machined surfaces equals 12
44、5unless otherwise specified. Figure 7Demolding Gauge Assemblies 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.7. MATERIAL 7.1. Asphalt BinderPAV-aged or RTFO-plus-PAV-aged asphalt binder or recovered
45、binder from aged pavement. 7.2. Release AgentA mixture of 20 g of glycerin and 20 g of talc (USP) shall be used as a release agent for the aluminum molds. 7.3. Release FilmMylar, or similar, cut to the same size as the bottom mold plate. 7.4. Solvent (Varsol or Mineral Spirits) or a Degreasing Spray
46、 Cleanerformulated for use on asphalt for cleaning molds, end tabs, and plates. 7.5. Cotton Cleaning Clothsfor wiping molds, end tabs, and plates. 8. HAZARDS 8.1. Use standard laboratory safety procedures required for handling the hot asphalt binder when preparing test specimens and safety procedure
47、s required when cleaning with solvents or degreasers. 9. CALIBRATION AND STANDARDIZATION 9.1. Initial Loading Pin Distance Adjustment: 9.1.1. Adjust the distance between the two loading pins attached to the loading frame by matching the cavities of the demolding gauge to the loading pins (Figure 8).
48、 The demolding gauge should be able to slide in and out of the two loading pins smoothly. Adjust the distance between loading heads to achieve the proper spacing. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applic
49、able law.Figure 8Loading Frame Pins Distance Adjustment 9.2. Loading frame friction calibration. 9.2.1. Perform a test without a specimen to determine the frictional force of the loading frame. Repeat this friction test for various loading rates and record the average frictional force for use during data interpretation. 9.2.2. The obtained frictional force needs to be subtracted from the measured force before transforming the measured force to an average true
