1、Standard Method of Test for Estimating Fatigue Resistance of Asphalt Binders Using the Linear Amplitude Sweep AASHTO Designation: TP 101-12 (2015)1American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2b TP 101-1 AASHTO
2、Standard Method of Test for Estimating Fatigue Resistance of Asphalt Binders Using the Linear Amplitude Sweep AASHTO Designation: TP 101-12 (2015)11. SCOPE 1.1. This test method covers the determination of an asphalt binders resistance to fatigue damage by means of cyclic loading employing systemati
3、c, linearly increasing load amplitudes. The amplitude sweep is conducted using the Dynamic Shear Rheometer (DSR) at the intermediate pavement temperature determined from the performance grade (PG) of the asphalt binder according to M 320. The test method can be used with binder aged using T 240 (RTF
4、OT) and R 28 (PAV) to simulate the aging for in-service asphalt pavements. 1.2. The values stated in SI units are to be regarded as the standard. 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 s
5、tandard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 320, Performance-Graded Asphalt Binder R 28, Accelerated Aging of Asphalt Binder Using a Pressurized Aging Vessel (PAV
6、) T 240, Effect of Heat and Air on a Moving Film of Asphalt Binder (Rolling Thin-Film Oven Test) T 315, Determining the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer (DSR) 2.2. ASTM Standard: D8, Standard Terminology Relating to Materials for Roads and Pavements 3. TERMINO
7、LOGY 3.1. Definitions: 3.1.1. Definitions of terms used in this test method may be found in ASTM D8, determined from common English usage, or combinations of both. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applic
8、able law.TS-2b TP 101-2 AASHTO 4. SUMMARY OF TEST METHOD 4.1. Asphalt binder is first aged using T 240 (RTFOT) to represent short-term aging of asphalt pavements. The binder may be further aged using R 28 (PAV) prior to testing in order to simulate long-term aging of asphalt pavements. A sample is p
9、repared according to T 315 (DSR) using the 8-mm parallel plate geometry with a 2-mm gap setting. The sample is tested in shear using a frequency sweep to determine its rheological properties. The sample is then tested using a series of oscillatory load cycles at systematically increasing amplitudes
10、at a constant frequency to cause accelerated fatigue damage. The continuum damage approach is used to calculate the fatigue resistance from the rheological properties and amplitude sweep results. 5. SIGNIFICANCE AND USE 5.1. This method is intended to evaluate the ability of an asphalt binder to res
11、ist fatigue damage by employing cyclic loading at increasing amplitudes in order to accelerate damage. The characteristics of the rate of damage accumulation in the material can be used to indicate the fatigue performance of the asphalt binder given pavement structural conditions and/or expected amo
12、unt of traffic loading using predictive modeling techniques. 6. APPARATUS 6.1. Use the apparatus as specified in T 315. 7. PROCEDURE 7.1. Condition the asphalt binder in accordance with T 240 (RTFOT) for short-term performance, or condition the asphalt binder in accordance with T 240 (RTFOT) followe
13、d by R 28 (PAV) for long-term performance. 7.2. Sample PreparationThe sample for the Amplitude Sweep is prepared following T 315 for 8-mm plates. The temperature control also follows the T 315 requirements. 7.2.1. This test may be performed on the same sample that was previously used to determine th
14、e rheological properties in the DSR on PAV residue as specified in M 320. 7.3. Test ProtocolTwo types of testing are performed in succession. The first test, a frequency sweep, is designed to obtain information on the rheological properties, and the second test, an amplitude sweep, is intended to me
15、asure the damage characteristics of the material. 7.3.1. Determination of “Alpha” ParameterIn order to perform the damage analysis, information regarding the undamaged material properties (represented by the parameter ) must be determined. The frequency sweep procedure outlined in Section 7.3.1.1 is
16、 used to determine the alpha parameter. 7.3.1.1. Frequency SweepFrequency sweep test data are used to determine the damage analysis “alpha” parameter. The frequency sweep test is performed at the selected temperature and applies oscillatory shear loading at constant amplitude over a range of loading
17、 frequencies. For this test method, the frequency sweep test is selected from the DSR manufacturers controller software, employing an applied load of 0.1 percent strain over a range of frequencies from 0.2 to 30 Hz. Data are sampled at the following 12 unique frequencies (all in Hz): 0.2 0.4 0.6 0.8
18、 1.0 2.0 4.0 6.0 8.0 10 20 30 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 101-3 AASHTO Complex shear modulus |G*|, Pa and phase angle , degrees are recorded at each frequency, as shown in Fi
19、gure 1. Figure 1Example Output from Frequency Sweep Test 7.3.2. Amplitude SweepThe second test is run at the selected temperature using oscillatory shear in strain-control mode at a frequency of 10 Hz. The loading scheme consists of 10-s intervals of constant strain amplitude, where each interval is
20、 followed by another interval of increased strain amplitude as follows: 0.1 percent, 1.0 percent, 2.0 percent, 3.0 percent, 4.0 percent, 5.0 percent, 6.0 percent, 7.0 percent, 8.0 percent, 9.0 percent, 10 percent, 11 percent, 12 percent, 13 percent, 14 percent, 15 percent, 16 percent, 17 percent, 18
21、 percent, 19 percent, 20 percent, 21 percent, 22 percent, 23 percent, 24 percent, 25 percent, 26 percent, 27 percent, 28 percent, 29 percent, 30 percent. Peak shear strain and peak shear stress are recorded every 10 load cycles (1 s), along with phase angle , degrees and dynamic shear modulus |G*|,
22、Pa. Figure 2Loading Scheme for Amplitude Sweep Test 8. CALCULATION AND INTERPRETATION OF RESULTS 8.1. In order to determine the parameter from frequency sweep test data, the following calculations are performed: 0.1 1.0 10.0 100.01.0E + 081.0E + 071.0E + 061.0E + 05Complex ShearModulus58565452504846
23、444240Complex Shear Modulus, PaPhaseAngle,degreesFrequency, HzFrequency Sweep DataPhase Angle0 500 1000 1500 2000 2500 3000 350005101520253035AppliedStrain, %Loading Cycles 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation
24、of applicable law.TS-2b TP 101-4 AASHTO 8.1.1. First, data for the dynamic modulus |G*|() and phase angle () for each frequency are converted to storage modulus, G(): G() = |G*|() cos () (1) 8.1.2. A best-fit straight line is applied to a plot with log on the horizontal axis and log G() on the verti
25、cal axis using the form: log G() = m(log ) + b (2) 8.1.3. The value obtained for m is recorded and the value of is obtained by performing the following transformation: 11m= + (3) 8.2. For the results of the amplitude sweep test, the data are analyzed as follows: Note 1The following damage calculatio
26、n method is adapted from Kim et al. (see Section 12.1). 8.2.1. The damage accumulation in the specimen is calculated using the following summation: ( )( )( )121110 1sin sinNi D i i iiDt I G G t t+= (4) where: ID= initial value of |G*| from the 1.0 percent applied strain interval, MPa; 0= applied str
27、ain for a given data point, percent; |G*| = complex shear modulus, MPa; = value reported in Section 7.1.3; and t = testing time, s. 8.2.2. Summation of damage accumulation begins with the first data point for the 1.0 percent applied strain interval. The incremental value of D(t) at each subsequent p
28、oint is added to the value of D(t) from the previous point. This is performed up until the final data point from the test at 30 percent applied strain. 8.2.3. For each data point at a given time t, values of |G*| sin and D(t) are recorded (it is assumed that |G*| sin at D(0) is equal to the average
29、undamaged value of |G*| sin from the 0.1 percent strain interval, and D(0) = 0). The relationship between |G*| sin and D(t) can then be fit to the following power law: ( )2*01sinCG C CD= (5) where: C0= the average value of |G*| sin from the 0.1 percent strain interval; and C1and C2= curve-fit coeffi
30、cients derived through linearization of the power law adapted from Hintz, et al., in the form shown below: ( )( ) ( )*0 12log sin log logCG CC D=+ (6) 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2
31、b TP 101-5 AASHTO Using the above equation, C1is calculated as the antilog of the intercept and C2is calculated as the slope of line formed as log(C0 |G*| sin ) versus log(D). For calculation of both C1and C2, data corresponding to damages less than 100 are ignored. 8.3. The value of D(t) at failure
32、, Df, is defined as the D(t) that corresponds to a 35 percent reduction in undamaged |G*| sin (C0). The calculation is as follows: ( )21010.35=CfCDC(7) 8.4. The following parameters (A35and B) for the binder fatigue performance model can now be calculated and recorded as follows: ( )( )3512kfDfDAk I
33、 CC=(8) where: f = loading frequency (10 Hz); k = 1 + (1 C2); and B = 2. 8.5. The binder fatigue performance parameter Nfcan now be calculated as follows: Nf= A35(max)B (9)where: max= the maximum expected binder strain for a given pavement structure, percent. 9. REPORT 9.1. Report the following: 9.1
34、.1. Sample identification; 9.1.2. PG grade; 9.1.3. Test temperature, nearest 0.1C; 9.1.4. Fatigue model parameters A35and B, four significant figures; and 9.1.5. Binder fatigue performance parameter Nf, nearest whole number. 10. PRECISION AND BIAS 10.1. To be determined upon results of interlaborato
35、ry testing. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 101-6 AASHTO 11. KEYWORDS 11.1. Asphalt binder; continuum damage; DSR; fatigue; performance grading. 12. REFERENCES 12.1. Kim, Y., H.
36、J. Lee, D. N. Little, and Y. R. Kim. “A simple testing method to evaluate fatigue fracture and damage performance of asphalt mixtures.” Journal of Association of Asphalt Paving Technologists, Vol. 75, 2006, pp. 755788. 12.2. Hintz, C., R. Velasquez, C. Johnson, and H. Bahia. “Modification and valida
37、tion of the linear amplitude sweep test for binder fatigue specification.” In Transportation Research Record TBD: Journal of the Transportation Research Board. Transportation Research Board, National Academies of Sciences, Washington, DC, 2011, pp. 96106. APPENDIXES (Nonmandatory Information) X1. SA
38、MPLE CALCULATIONS X1.1. Example data from the amplitude sweep test are given in Table X1.1. Table X1.1Example Data Output from Amplitude Sweep Test Testing Time, s Shear Stress, MPa Shear Strain, % |G*|, MPa Phase Angle, degrees |G*| sin , MPa 34 0.212 1.996 10.646 49.18 8.057 35 0.212 2.001 10.619
39、49.22 8.041 36 0.212 2.003 10.595 49.26 8.028 37 0.211 2.003 10.574 49.29 8.016 38 0.211 2.004 10.555 49.32 8.005 39 0.211 2.003 10.539 49.34 7.995 40 0.210 2.003 10.524 49.37 7.987 X1.2. The following values have already been assumed: D(33) = 10.77 = 2.58 ID= 8.345 MPa |G*| sin t = 33= 8.075 MPa X1
40、.3. Sample calculations: X1.3.1. To calculate the accumulation of damage from t = 33 sec to t = 34 sec: 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 101-7 AASHTO ( ) ( )( )( )12* * 110134 33
41、sin sinD i i iiD D I G G tt+=+ ( ) ( ) ( )( ) ( ) ( )2.58121 2.581 2.5834 33 8.345 1.996 8.075 8.057 34 33DD+=+ ( )34 12.36D = X1.3.2. This procedure is repeated, giving the following results shown in Table X1.2. Table X1.2Example Data Output and Damage Calculation from Amplitude Sweep Test Testing
42、Time, s Shear Stress, MPa Shear Strain, % Complex Modulus, MPa Phase Angle, degrees |G*| sin, MPa D(t) 34 0.212 1.996 10.646 49.18 8.057 12.36 35 0.212 2.001 10.619 49.22 8.041 13.79 36 0.212 2.003 10.595 49.26 8.028 15.06 37 0.211 2.003 10.574 49.29 8.016 16.26 38 0.211 2.004 10.555 49.32 8.005 17.
43、35 39 0.211 2.003 10.539 49.34 7.995 18.40 40 0.210 2.003 10.524 49.37 7.987 19.26 X2. EXAMPLE PLOTS X2.1. The following example plots may be useful in visualizing the results: Figure X2.1Example |G*| sin versus Damage Plot with Curve-Fit from Section 7.2 2015 by the American Association of State Hi
44、ghway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2b TP 101-8 AASHTO Figure X2.2Plot of Fatigue Parameter Nf(Normalized to 1 million ESALs) versus Applied Binder Shear Strain on a Log-Log Scale (Allowable fatigue life can be determined for given
45、strain amplitudes, as shown by the arrows.) 1This provisional standard was first published in 2012. 1.E + 011.E + 001.E 011.E 021.E 031.E 041.E 051 10Applied Shear Strain, %(Pavement Structure Indicator)Nf/ESALs(TrafficVolumeIndicator)Fatigue Law: Nf= A(gmax)BAB 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
