1、Standard Method of Test for Measuring Interfacial Fracture Energy of Hot-Poured Asphalt Crack Sealant Using a Blister Test AASHTO Designation: T 371-171Technical Section: 4e, Joints, Bearings, and Geosynthetics Release: Group 2 (June 2017) American Association of State Highway and Transportation Off
2、icials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4e T 371-1 AASHTO Standard Method of Test for Measuring Interfacial Fracture Energy of Hot-Poured Asphalt Crack Sealant Using a Blister Test AASHTO Designation: T 371-171Technical Section: 4e, Joints, Bearings, and Geosyntheti
3、cs Release: Group 2 (June 2017) 1. SCOPE 1.1. The blister test is used to determine the interfacial fracture energy (IFE) of hot-poured asphalt crack sealant at the application temperature as specified in MP 25 and PP 85. 1.2. The blister test is a fracture test. The objective of the test is to appl
4、y tensile forces using hydrostatic pressure to delaminate sealant from a substrate. A thin film of sealant is poured on the top of a substrate (usually aluminum) disk that has a hole at the center. Hydrostatic pressure is applied through this hole at a constant flow rate causing delamination between
5、 the sealant film and substrate. Sealant deformation and applied hydrostatic pressure are recorded as a function of time. The amount of energy required to achieve complete delamination is called interfacial fracture energy and can be calculated from the pressure-deformation curve. This energy is con
6、sidered a measure of bonding potential. 1.3. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish and follow appropriate health and safety practices and to determine the applicability
7、 of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: MP 25, Performance-Graded Hot-Poured Asphalt Crack Sealant PP 85, Grading or Verifying the Sealant Grade (SG) of a Hot-Poured Asphalt Crack Sealant R 18, Establishing and Implementing a Quality Management System f
8、or Construction Materials Testing Laboratories T 314, Determining the Fracture Properties of Asphalt Binder in Direct Tension (DT) T 367, Accelerated Aging of Hot-Poured Asphalt Crack Sealant Using a Vacuum Oven 2.2. ASTM Standards: D5167, Standard Practice for Melting of Hot-Applied Joint and Crack
9、 Sealant and Filler for Evaluation E1, Standard Specification for ASTM Liquid-in-Glass Thermometers 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-2 AASHTO E77, Standard Test Method for Ins
10、pection and Verification of Thermometers 3. TERMINOLOGY 3.1. Definitions: 3.1.1. hot-poured asphalt crack sealanthot-poured modified asphaltic material used to seal pavement cracks and joints. Note 1Based on the references, hot-poured asphalt crack sealant is typically applied at a temperature of 16
11、0C or above. 3.1.2. interfacial fracture energy (IFE)the energy required to separate hot-poured asphalt crack sealant from a substrate. 4. SUMMARY OF METHOD 4.1. Hot-poured asphalt crack sealant material is homogenized following the procedure given in ASTM D5167. For each test, including four replic
12、ates, cut 320 g of sealant and heat to the manufacturers recommended pouring temperature. Sealant will be poured in the mold assembled on top of an annular-shaped disk of substrate. An aluminum plug will be inserted into the hole of the substrate to close it. The sealant will be poured on top of the
13、 plugged substrate to provide a film of 4.6-mm thickness. Hydrostatic pressure is applied through the hole to cause delamination between the sealant film and the substrate. Sealant deformations and applied hydrostatic pressure can be recorded as a function of time. The amount of energy required for
14、complete delamination is called interfacial fracture energy and can be calculated from the pressure-deformation curve. This energy can be considered an indication of bonding potential. 5. SIGNIFICANCE AND USE 5.1. This procedure is designed to measure the adhesion potential of hot-poured sealant to
15、aggregate. 5.2. Sealants must be homogenized (ASTM D5167) before measuring adhesion by this method. 6. APPARATUS 6.1. Direct Tension Test (DTT) DeviceModified T 314 direct tension test (DTT) machine or an equivalent system with environmental chamber and motor or screw driven actuator; 6.2. Test Cham
16、berTest chamber that can reach 40 0.5C; 6.3. Laboratory OvenAny standard laboratory oven capable of producing and maintaining temperatures up to 200C 2.0C; 6.4. Release AgentA proper release agent to prevent the crack sealant from sticking to indicated test specimen mold setup pieces. A silicon-base
17、d release agent is recommended. 6.5. Test Specimen Mold SetupsFour aluminum molds, four plugs, and four rubber bands. (See Figures 1, 2, and 3.) 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 3
18、71-3 AASHTO Figure 1Schematic of the Substrate Disk Figure 2Schematic of the Plug 25 mm10 mm5 mm 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-4 AASHTO Figure 3Schematic of One Section of
19、the Four-Piece Mold 7. HAZARDS 7.1. Standard laboratory caution should be used in handling hot sealant in accordance with ASTM D5167 and when using the Direct Tension/Blister Tester (DTT/Blister). Required safety procedures should be followed when chemical agents are used. 8. PREPARATION OF APPARATU
20、S 8.1. The test setup used to hold the blister molds must be placed in the environmental bath or chamber and leveled to function properly. The environmental chiller must be adjusted to specific temperature. 9. CALIBRATION AND STANDARDIZATION 9.1. Temperature of the ovens should be standardized accor
21、ding to a quality management system meeting the requirements of R 18. 9.2. Temperature of the test chamber should be verified using calibrated thermometers according to ASTM E1, ASTM E77, and a quality management system meeting the requirements of R 18. 2017 by the American Association of State High
22、way and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-5 AASHTO 9.3. Thermometer (temperature detector)Verify the calibration of the temperature-sensing device to 0.1C every 6 months in accordance with ASTM E1 or ASTM E220, as applicable. 10.
23、PREPARATION OF SAMPLES AND TEST SPECIMENS 10.1. All hot-poured asphalt crack sealants to be tested must undergo accelerated aging according to T 367. It is recommended that a minimum of 150 g of hot-poured asphalt crack sealant be prepared for a set of tests. 10.2. Once aged, hot-poured asphalt crac
24、k sealant should be molded, cooled, and stored for later usage. To store the sealant, it is recommended that a can or plastic-lined box be used. The mold must be of sufficient size that the sealant depth is no greater than 100 mm to allow for rapid cooling. 10.3. Adjust the ovens temperature to the
25、recommended pouring temperature for the sealant being tested. 10.4. Turn on the DTT/Blister machine, load the program, and cool the test chamber to test temperature. 10.5. Use a compass to draw a circle 27 mm in diameter on adhesive-backed fluoropolymer (FEP) film. 10.6. Punch out the circle using a
26、 sharp manual punch. 10.7. Peel the FEP film and place it on a level surface, adhesive side up (Figure 4). 10.8. Place the needle on the center (marked with the compass) of the FEP film (Figure 4). 10.9. Place the flat side of the plug on top of the needle and let the needle go through the plug (Fig
27、ure 4). Figure 4Performing Steps 10.7 through 10.9 10.10. Press the plug on the film gently to make sure it has adhered to the film. 10.11. Spray release agent (Figure 5) on the plug while keeping it inclined. 2017 by the American Association of State Highway and Transportation Officials. All rights
28、 reserved. Duplication is a violation of applicable law.TS-4e T 371-6 AASHTO Figure 5Spraying Release Agent on the Plugs 10.12. Taking care not to contaminate the surface of the disk, place the plug on top of the annular disk (Figure 6). Figure 6Placing the Plug on the Annular Disk and Pulling It fr
29、om Underneath until the Disk Fits in the Hole and the Film Edges Sit on the Disk 10.13. Place the substrate disk and the plug on a setting board. 10.14. Spray release agent on the molds (Figure 7). Figure 7Spraying Release Agent on the Molds 2017 by the American Association of State Highway and Tran
30、sportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-7 AASHTO 10.15. Assemble the mold on top of the disk (Figure 8). Figure 8Assembling the Molds on Top of the Disk 10.16. Wrap the mold with a rubber band stretched through the groove around the mold to
31、 keep the components in place (Figure 9). Figure 9Using a Rubber Band to Keep the Mold Together 10.17. Prepare four cans of sealant by cutting 80 g of homogenized sealant for each. 10.18. Place the can in the oven for 15 min, remove it from the oven, stir the sealant thoroughly, and place it back in
32、 the oven for another 15 min. 10.19. Remove the can from the oven, stir the sealant thoroughly, and pour into all the assembled setups. Use four replicates for each sealant. Care should be taken in filling up the molds to prevent any trapped air bubbles in the samples (Figure 10). 2017 by the Americ
33、an Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-8 AASHTO Figure 10Pouring Sealant onto the Center Top of the Plug so that the Sealant Flows to Fill the Mold 10.20. Let samples set 1 h at room temperature (Fig
34、ure 11). Figure 11Sealant Setting for 1 h at Room Temperature 10.21. Trim the excessive sealant away with a heated putty knife (Figure 12). Move the putty knife once over and parallel to the interface of the sample; trimming direction shall not be changed during trimming. Use a well-heated putty kni
35、fe to prevent any shearing of the sealant. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-9 AASHTO Figure 12Trimming Excess Sealant with a Heated Putty Knife 10.22. Place the specimens on t
36、he cooling rack (Figure 13). Care should be taken not to disturb the specimens. Figure 13Placing the Disks on the Rack with Clearance between Each Specimen 10.23. Place the rack in the cooling bath for 15 min (Figure 14). 2017 by the American Association of State Highway and Transportation Officials
37、. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-10 AASHTO Figure 14Placing the Rack in the Bath for 15 min 10.24. Remove the rubber band and gently disassemble the mold of one specimen (Figure 15). Figure 15Disassembling the Mold 10.25. Remove the plug and place the s
38、pecimen back in the bath (Figure 16). 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-11 AASHTO Figure 16Removing the Plug from Each Specimen 10.26. Repeat steps 10.24 and 10.25 until all sp
39、ecimens are demolded. 10.27. Leave the specimens in the cooling bath for 45 min before running the test. 10.28. Open the Blister test builder program; then open the outlet valve to prevent pressure from being applied to the specimen before the test starts. Place the specimen on the setup and clamp t
40、he specimen tightly. Check the program settings and run the test. Record the data. 10.29. Examine the failure surfaces visually for each replicate to ensure adhesive failure occurred. If sealant cohesive breakage occurred, discard the data. (See Figure 17.) Note 1Sealant cohesive breakage is defined
41、 as rupture in the blister prior to the start of delamination or during delamination of sealant from the disk. Sealant pieces covering an area of approximately less than 10% of total disk area and remaining at the periphery of the disk after test completion is not considered as sealant cohesive brea
42、kage (See Figure 17.) A sudden drop of load is an indication of sealant cohesive breakage. Adhesive failure usually follows a gradual delamination of sealant from the disk and is reflected by a smooth load reduction as blister size increases. Figure 17Removing the Specimen and Verifying that the Typ
43、e of Failure Was Adhesive Failure, in Which Sealant Separates from the Disk 11. CALCULATION OF RESULTS 11.1. Find the maximum load (Pmax) to failure and its correspondent displacement (d). 11.2. Find the Interfacial Fracture Energy, IFE, by multiplying half of the maximum load and the corresponding
44、displacement. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-12 AASHTO maxIFE P d= (1) where: IFE = Interfacial Fracture Energy, J/m2 = the force factor and is equal to 0.5 Pmax= the maximu
45、m load to failure, N; and d = the displacement at the maximum load, m. 12. REPORT 12.1. Report the following information: 12.1.1. Sealant identification and supplier, 12.1.2. Lot number, 12.1.3. Date received, 12.1.4. Date of apparent viscosity measurement, 12.1.5. Recommended pouring temperature, 1
46、2.1.6. Safe heating temperature, 12.1.7. IFE, J/m2, and 12.1.8. Any deviations from test temperature. 13. PRECISION AND BIAS 13.1. Single-Operator Precision (Repeatability)The results obtained in the same laboratory by the same operator using the same equipment, in the shortest practical period of t
47、ime, should not be considered suspect unless the difference in the two results, expressed as a percent of their mean, exceeds the value given in Table 1. Table 1Precision Estimates Condition Coefficient of Variation (1s%)aSingle-operator precision: Average IFE (J/m2) 8.77 aThe precision estimate giv
48、en in Table 1 is based on the analysis of test results from 12 sealants with a wide range of rheological properties. The data analyzed include results from two operators in the same laboratory who conducted each test in four replicates. 14. KEYWORDS 14.1. Adhesion; blister; bond; crack; fillers; hot
49、-poured asphalt crack sealant; interfacial fracture energy; joint. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4e T 371-13 AASHTO 15. REFERENCES 15.1. Al-Qadi, I. L., J. F. Masson, E. Fini, S. H. Yang, and K. K. McGhee. Development of Performance-Based Guidelines for Selection of Bituminous-Based Hot-Poured Pavement Crack Sealant: An Executive Summary Report. VTRC 09-CR7. Virginia Transportation Research
