1、Standard Method of Test for Determination of Asphalt Binder Resistance to Ductile Failure Using Double-Edge-Notched Tension (DENT) Test AASHTO Designation: TP 113-151American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-
2、2b TP 113-1 AASHTO Standard Method of Test for Determination of Asphalt Binder Resistance to Ductile Failure Using Double-Edge-Notched Tension (DENT) Test AASHTO Designation: TP 113-1511. SCOPE 1.1. This test method covers the determination of an asphalt binders resistance to ductile failure using a
3、 double-edge-notched tension test. 1.2. The test is conducted after thermal conditioning to determine the essential work of failure, the plastic work of failure, and an approximate critical crack tip opening displacement at a specified temperature and rate of loading. 1.3. The values stated in SI un
4、its are to be regarded as the standard. 1.4. 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 appropriate safety and health practices and determine the applicability of regulatory
5、 limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: R 28, Accelerated Aging of Asphalt Binder Using a Pressurized Aging Vessel (PAV) T 240, Effect of Heat and Air on a Moving Film of Asphalt Binder (Rolling Thin-Film Oven Test) T 300, Force Ductility Test of Asphalt Materials 3
6、. TERMINOLOGY 3.1. Definitions: 3.1.1. Wttotal work of failure, area under the load versus load-line displacement curve, J (cal). 3.1.2. wtspecific total work of failure (Wt /B), kJ/m2(kcal/in.2). 3.1.3. wespecific essential work of failure, the energy required to fracture or break the sample withou
7、t plastic deformation away from the fracture zone, kJ/m2(kcal/in.2). 3.1.4. wpspecific plastic work of failure term, the non-essential work dissipated during the deformation of a volume of asphalt around the failure zone, MJ/m3(Mcal/in.3). 3.1.5. geometric constant describing the shape of the plasti
8、c zone. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 113-2 AASHTO 3.1.6. tcritical crack tip opening displacement also referred to as CTOD, mm (in.). 3.1.7. Pload, N (lbf). 3.1.8. ddisplaceme
9、nt in test, m (in.). 3.1.9. Bsample thickness, m (in.). 3.1.10. ligament length, the space between the notches, m (in.). 3.1.11. nnet section stress of sample, N/m2(psi). 4. APPARATUS 4.1. Testing ApparatusA constant rate of displacement device capable of maintaining displacement at rates of 100 2.5
10、 mm/min (4 0.1 in./min). The maximum stroke for the instrument(s) shall be 1000 mm (39.5 in.) or greater. The apparatus shall have a set of loading pins that ensure precise alignment of the sample during the test. The apparatus shall be able to determine displacement to an accuracy of 0.05 mm ( 0.00
11、2 in.). Note 1The DENT testing apparatus is commonly a force-ductility apparatus installed in a ductilometer. 4.2. Load SensorThe sensitivity of the load sensor and recording electronics shall allow the load, P, to be measured every 0.3 s during the test with an accuracy of at least 1 percent. The l
12、oad sensor shall be capable of measuring a nominal maximum force of up to 133 N (30 lbf). 4.3. Temperature-Controlled Bath for TestingThe bath shall be large enough to contain the testing apparatus and samples in their molds prior to testing under 25 mm (1 in.) of water. The equipment shall be capab
13、le of maintaining the water at the testing temperature to an accuracy of at least 0.5C (0.9F). 4.4. Temperature-Controlled Bath for ConditioningA bath capable of maintaining a minimum of 25 mm (1 in.) of water over the sample at the conditioning temperature requirements to within 0.5C (0.9F). Typica
14、lly, the temperature controlled bath for testing is utilized. 4.5. Metal Stirring RodStick capable of stirring the hot asphalt binder vigorously. 4.6. Base PlatesThe base plates shall be made of non-absorbent material of sufficient thickness to prevent deformation and of a sufficient size to hold fr
15、om one to three molds, but still able to fit in the temperature-controlled bath for conditioning. The plate shall be uniformly flat to ensure that the bottom surfaces of each mold will touch it throughout. 4.7. MoldConsists of two end pieces for each sample and a silicone mold. Note 2User agencies a
16、nd asphalt binder suppliers may agree on an all metal design for the molds provided it does not deviate from the dimensions and tolerances given. 4.7.1. Silicone MoldConsists of a silicone mold with the dimensions shown in Figure 1 with capability of forming three samples. 2015 by the American Assoc
17、iation of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 113-3 AASHTO Note: All dimensions in mm, and general tolerance is 0.2 mm (0.008 in.). Figure 1Dimensions of Silicone Molds 4.7.1.1. DENT End PiecesFor three samples, six al
18、uminum end pieces with dimensions given in Figure 2. Note: All dimensions in mm, and general tolerance is 0.2 mm (0.008 in.). Figure 2DENT End Pieces 41.25 41.2542151053015141488.5142152.512.752021.35148+389.0215.05Dia 7.074.130.112.752.38.151.351.35 2015 by the American Association of State Highway
19、 and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 113-4 AASHTO 5. PREPARATION OF SAMPLES 5.1. Preparation of ApparatusPlace the mold on the base plate and insert the DENT end pieces. 5.2. Six samples shall be prepared using PAV-aged asphalt bind
20、er, two for each ligament length of 15, 10, and 5 mm (0.60, 0.40, and 0.20 in.) by fitting each of the three pairs of inserts firmly within their recessed positions in the silicone molds. 5.2.1. Asphalt binder shall be aged according to T 240 (RTFO) and R 28 (PAV). The aged asphalt binder shall then
21、 be heated for 1 h at 160 5C (320 9F) to ensure that the material readily flows when dispensed from the container into the prepared molds. Note 3The heating temperature may be raised to a maximum of 180C (356F) to provide a low-enough viscosity, but the sample material shall not be overheated. 5.3.
22、Prior to pouring the asphalt binder into the mold, measure and record the actual ligament length, , to within 0.1 mm (0.004 in.). 5.4. After thorough stirring, pour the asphalt material into the mold, taking care not to entrain any air bubbles. Pour the material in a thin stream back and forth from
23、end to end until the mold is level full. In filling the mold, take care not to disarrange the end pieces or distort the sample. Most accurate sample thicknesses are obtained by pouring the asphalt on an analytical balance at a constant weight for each specimen. Let the mold and contents cool to room
24、 temperature for 30 to 40 min, and then place the base plate and filled mold in the water bath maintained at the specified test temperature for 30 min. 5.5. Measure and record the sample thickness, B, in millimeters (inches) to 4 (4) decimal places to 0.1 mm (0.0001 in.). If the sample is flush with
25、 the mold, B will be equal to the thickness of the mold. 6. TEST PROCEDURES 6.1. Condition the samples on the base plates at 25 0.5C (77 0.9F) for 3 h 5 min in their molds in a temperature controlled bath under a minimum of 25 mm (1 in.) of water. 6.2. Once conditioned, prepare the sample for testin
26、g, without causing excessive deformation or stress concentrations to the sample, by removing the sample from the mold. Keep the sample always under the surface of the water, and load it through the holes in the end pieces onto the testing apparatus loading pins. The sample shall be loaded so there i
27、s a minimum of 25 mm (1 in.) of water below and above the sample. Allow the sample to sit and equilibrate for a minimum of 5 min before starting the test. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
28、TS-2b TP 113-5 AASHTO Note: Water was omitted in this photograph to improve the image quality but specimens are to be kept under water at all times. Figure 3DENT Samples Placed on Loading Pins 6.3. Perform the test according to T 300, but at a displacement rate of 100 2.5 mm/min (4 0.01 in./min) in
29、a bath maintained at 25 0.5C (77 0.9F), until ductile failure is reached or a stroke length of 1000 mm (39.5 in.) is reached. 6.4. If ductile failure is not achieved before a displacement of 1000 mm (39.5 in.) is reached, the test shall be stopped and the material retested as follows at a lower temp
30、erature: reheat the sample in a manner that minimizes damage to the material (see Section 5), prepare the sample according to Section 5, and condition and retest according to steps in Sections 6.1, 6.2, and 6.3 at a temperature of 15 0.5C (59 0.9F) after 3 h 5 min in the molds in a temperature-contr
31、olled bath under a minimum of 25 mm (1 in.) of water. 6.5. Record the actual sample ligament length, (as measured according to Section 5.3). Record displacement rate, water bath temperature, and load (every 0.3 s) for the entire test time. 6.6. Repeat steps in Sections 6.1 through 6.5 on the duplica
32、te sample and then on all the other ligament length samples. 7. CALCULATIONS 7.1. Calculate Wtfor each sample, where Wtis: Wt= 0, kJftPd(1) tf= time when ductile failure or the maximum stroke length is reached (see Section 6.4), whichever comes first. Note 4Any negative load readings or negative W(t
33、) values are not to be included in calculating Wt. Any W(t) obtained after tfare not to be included in calculating Wt. Although it is not always noticeable, additional data is often recorded for the run after failure. For example when the load is very small and then increases slightly or the load is
34、 very small and remains constant, this data is a residual load on the device. Please check each of the run sheets to ensure that these residual and any initial pre-start values are zeroed so they are not included in the total Wt. 7.2. Calculate wtfor each sample for each Wtwhere: wt= (Wt)/(B), J/m2(
35、cal/in.2). (2) 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 113-6 AASHTO 7.3. Plot wtfor the three ligament lengths, , and draw a best fit straight line (see Figure 4 for an example). From th
36、e graph or using the method of least squares fitting, obtain values for we, and the term wp, where: weis the specific essential work of failure, i.e., wtfor = 0.0 mm (in.). wpis the slope of the best fit straight line, for wt= we+ wp. 7.4. Determine t= we/n, where: ( )/n peakPB= (3) Ppeak = average
37、peak load obtained for the sample tested with the smallest ligament length, i.e., the average maximum load for the 5 mm (0.2 in.) ligament samples. is the average sample thickness for the 5mm runs. is the average ligament length for the 5 mm runs. 8. REPORT 8.1. Report the following information (see
38、 Figure 6 for an example): 8.1.1. Sample identification; 8.1.2. Test temperature, to the nearest 0.1C; 8.1.3. we; 8.1.4. wp; 8.1.5. t; 8.1.6. Ppeak; 8.1.7. Best fit line for the wtversus ligament lengths plot and the plot (see Figure 4, for example); and 8.1.8. For each ligament length, provide the
39、following: 8.1.8.1. Actual sample ligament length, 8.1.8.2. Actual sample thickness, 8.1.8.3. Wt , 8.1.8.4. wt, and 8.1.8.5. Load versus displacement curves (see Figure 5, for example). 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is
40、 a violation of applicable law.TS-2b TP 113-7 AASHTO Figure 4Example wtversus Ligament Length Plot for Determining Essential Work of Failure, we Figure 5Typical Duplicate Load-Displacement Curves for Essential Work of Failure Test 005 101015 2020304050Ligament Length, mmwt,SpecificTotalWork,k/m2 y =
41、 1.8x + 9.52R2= 0.99Specific Total Works of Fracture0050 10010150 2002030300250350Displacement, mmLoad, NLoad Displacement Curves5 mmRun 15 mmRun 210 mmRun 110 mmRun 215 mmRun 115 mmRun 2 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication
42、is a violation of applicable law.DENT Test Reporting Sheet PG Grade: Test Temp, C: Date of Test: Sample: Tested by: RESULTS: Run 1 Run 2 Ligament length 5 10 15 5 10 15 mm , measured ligament length m B, measured sample thickness m Wt, total work of failure J wt, specific total work of failure kJ/m2
43、we, specific essential work of failure kJ/m2wp, specific essential work of failure term MJ/m3Ppeak, average peak load for 5-mm runs N t, CTOD mm CHARTS: COMMENTS: Figure 6Example Reporting Sheet 00.005 10 15 200.100.200.300.400.500.600.700.800.901.00Ligament Length (mm)wt,specific totalwork (kJ/m2)y
44、 = 0R2= #N/ASpecific Total Work of Fracture00.025 10075 1250.10.20.30.40.50.60.70.80.91.0Displacement (mm)Load (N)Load vs. Displacement Curves505 mmRun 15 mmRun 210 mmRun 110 mmRun 215 mmRun 115 mmRun 2TS-2bTP 113-8AASHTO 2015 by the American Association of State Highway and Transportation Officials
45、.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 113-9 AASHTO 9. PRECISION AND BIAS 9.1. PrecisionThe research required to develop precision estimates has not been conducted. 9.2. BiasThe research required to establish the bias has not been conducted. 10. KEYWORDS 10.1. As
46、phalt binders; DENT; double-edge-notched tension; ductile failure; fatigue; specification testing. 1This provisional standard was first published in 2015. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
