1、Standard Practice for Evaluating the Elastic Behavior of Asphalt Binders Using the Multiple Stress Creep Recovery (MSCR) Test AASHTO Designation: R 92-181Technical Section: 2b, Liquid Asphalt Release: Group 3 (August) American Association of State Highway and Transportation Officials 444 North Capit
2、ol Street N.W., Suite 249 Washington, D.C. 20001 TS-2b R 92-1 AASHTO Standard Practice for Evaluating the Elastic Behavior of Asphalt Binders Using the Multiple Stress Creep Recovery (MSCR) Test AASHTO Designation: R 92-181Technical Section: Group 2b, Liquid Asphalt Release: Group 3 (August) 1. SCOP
3、E1.1. This practice provides a means of evaluating the elastic behavior of an asphalt binder by using theresults (percent recovery and non-recoverable creep compliance) from the Multiple Stress CreepRecovery (MSCR) test. The MSCR test is conducted using the Dynamic Shear Rheometer (DSR)at a specifie
4、d temperature. It is primarily intended for use with residue from T 240 (Rolling Thin-Film Oven Test (RTFOT), but may also be run on residue from R 28 (Pressurized Aging Vessel(PAV).1.2. The elastic behavior of an asphalt binder can provide insight to the technologist indicating to whatextent, if an
5、y, the binder could be modified with an elastomeric polymer.1.3. This practice may be used in conjunction with M 320 or M 332.1.4. The values stated in SI units are to be regarded as the standard.1.5. This standard does not purport to address all of the safety concerns, if any, associated with its u
6、se.It is the responsibility of the user of this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limitations prior to use.2. REFERENCED DOCUMENTS2.1. AASHTO Standards: M 320, Performance-Graded Asphalt Binder M 332, Performance-Graded Asphalt
7、 Binder Using the Multiple Stress Creep Recovery(MSCR) Test R 28, Accelerated Aging of Asphalt Binder Using Pressurized Aging Vessel (PAV) T 240, Effect of Heat and Air on Moving Film of Asphalt (Rolling Thin-Film Oven Test) T 315, Determining the Rheological Properties of Asphalt Binder Using a Dyn
8、amic ShearRheometer (DSR) T 350, Multiple Stress Creep Recovery (MSCR) Test of Asphalt Binder Using a Dynamic Shear Rheometer (DSR) 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2b R 92-2 AASHTO 2.
9、2. 2.3. ASTM Standard: D8, Standard Terminology Relating to Materials for Roads and Pavements Other Reference: LTPP Seasonal Asphalt Concrete Pavement Temperature Models, http:/ 3. TERMINOLOGY3.1. Definitions:3.1.1. Definitions of terms used in this practice may be found in ASTM D 8, determined from
10、 commonEnglish usage, or combinations of both.3.2. Definitions of Terms Specific to This Standard:3.2.1. creep and recoverya standard rheological test protocol whereby a specimen is subjected to aconstant load for a fixed time period and then allowed to recover at a constant zero load for a fixedtim
11、e period.3.2.2. non-recoverable creep compliance (Jnr)the residual strain in a specimen after a creep andrecovery cycle divided by the stress applied.3.2.3. Average percent recovery (R)the ratio of the difference between the peak strain and the residualstrain to the peak strain, expressed as a perce
12、ntage. This is a measure of the elastic response of anasphalt binder at a given temperature and applied stress level.4. SUMMARY OF PRACTICE4.1. This practice is used to evaluate the elastic response of an asphalt binder under shear creep andrecovery at a specified temperature. For most asphalt binde
13、rs, this temperature will be the hightemperature grade as determined only by environmental conditions (not as adjusted for trafficspeed or loading).4.2. Asphalt binder is first aged in accordance with T 240 (RTFOT). A sample of the RTFO-agedasphalt is tested in accordance with T 350 (MSCR). Unless o
14、therwise specified, the 25-mmparallel plate geometry is used with a 1-mm gap setting. The sample is tested in creep andrecovery at two stress levels. The stress levels used are 0.1 kPa and 3.2 kPa. The creep portion ofthe test lasts for one second which is followed by a nine-second recovery. Ten cre
15、ep and recoveryconditioning cycles are first conducted at a shear stress of 0.1 kPa. The test is then executed byconducting ten creep-recovery cycles at each shear stress level (0.1 and 3.2 kPa). Two parametersare derived from the MSCR test: the non-recoverable creep compliance (Jnr) and percent rec
16、overy(R).4.3. Using the Jnrand R values from testing conducted at 3.2 kPa shear stress (identified as Jnr-3.2 andR-3.2, respectively) data is compared to a curve of R as a function of Jnr. Values that plot on orabove the curve are considered to represent an asphalt binder with a significant elastic
17、responseindicative of modification using elastomeric polymers.4.3.1. As an alternative, the equation of the curve may be used and the R-3.2 value compared to the calculated minimum R-3.2 value determined using the measured Jnr-3.2 value. 2018 by the American Association of State Highway and Transpor
18、tation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2b R 92-3 AASHTO 5. SIGNIFICANCE AND USE 5.1. This practice is used to evaluate the elastic response of an asphalt binder under shear creep and recovery at a specified temperature in accordance with T 350. 6. APPA
19、RATUS 6.1. Use apparatus as specified in T 315, T 240, T 350, and R 28. 7. PROCEDURE 7.1. ConditioningUnless otherwise specified, condition the asphalt binder to be tested in accordance with T 240 (RTFOT). 7.2. Sample Preparation and TestingPrepare test specimens and test the specimens in accordance
20、 with T 350. For most asphalt binders, the test temperature will be the high temperature grade as determined only by environmental conditions (not as adjusted for traffic speed or loading) using the LTPPBind 3.1 software or the principles behind the temperature determination in LTPPBind. In the abse
21、nce of this information, use the temperature that corresponds to the high temperature grade of the standard unmodified grade of asphalt binder that would be used for the project location. 7.3. AnalysisAfter determining the Jnr-3.2 and R-3.2 values for the asphalt binder at the specified temperature,
22、 plot the data on Figure 1. Data that is plotted on or above the curve in Figure 1 is considered to have a significant elastic response for the associated value of non-recoverable creep compliance (indicating that the asphalt binder has been modified by an elastomeric polymer). Note: The curve stops
23、 at Jnr-3.2 = 2.00 kPa1and 0.1 kPa1. Jnr-3.2 values greater than 2.00 kPa1are not required to have any minimum R-3.2 value. Jnr-3.2 values less than 0.1 kPa1are required to have a minimum R-3.2 value of 55 percent. Figure 1Comparison of MSCR Jnr-3.2 and R-3.2 to Assess Elastic Response 0.00 0.50 1.0
24、0 1.50 2.00 2.500102030100908070605040Jnr-3.2 kPa1R-3.2,percent 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2b R 92-4 AASHTO 7.3.1. Alternatively, if the Jnr-3.2 value is between 0.10 and 2.00 kP
25、a1, inclusive, substitute the Jnr-3.2 value determined from testing the asphalt binder into the equation as shown below and solve for the minimum required R-3.2 value. ( )0.2633min-3.2 29.371 -3.2nrRJ= (1) where: R-3.2min= minimum required value of R-3.2 to indicate significant elastic behavior, per
26、cent Jnr-3.2 = measured value of Jnr-3.2 from T 350 testing, kPa17.3.2. If the Jnr-3.2 value is less than 0.10 kPa1then the R-3.2minvalue is 55.0 percent. 7.3.3. If the Jnr-3.2 value is greater than 2.00 kPa1then the R-3.2minvalue is 0.0 percent. 7.3.4. Compare the measured value of R-3.2 from T 350
27、 testing to the R-3.2minvalue as determined in Sections 7.4.1 to 7.4.3 (represented by the curve shown in Figure 1). If the measured R-3.2 value equals or exceeds the R-3.2minvalue, then the asphalt binder sample is considered to have shown a significant elastic response for the associated value of
28、non-recoverable creep compliance indicating that the asphalt binder has been modified. Note 1The R-Jnrand R-3.2minvalues described in Sections 7.3.1 through 7.3.3 (represented by the curve shown in Figure 1) are intended to be used to evaluate the elastic response of modified asphalt binders when te
29、sted at the appropriate climatic temperature. It should not be used with asphalt binders that have Jnr-3.2 values greater than 2.00 kPa1. 8. REPORT 8.1. Report the following information: 8.1.1. Sample identification; 8.1.2. PG grade and test temperature, nearest 0.1C; 8.1.3. Average percent recovery
30、 at 3.2 kPa, R-3.2, to nearest 0.1 percent; 8.1.4. Non-recoverable creep compliance at 3.2 kPa, Jnr-3.2, to nearest 0.01 kPa1; and 8.1.5. Figure 1 with data point plotted representing the measured Jnr-3.2 and R-3.2 values or calculation showing the minimum required value of R-3.2 (R-3.2min) compared
31、 to the measured R-3.2 value to indicate significant elastic behavior. 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. 2018 by the American Association of Sta
32、te Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2b R 92-5 AASHTO 10. KEYWORDS 10.1. Asphalt binders; creep and recovery; creep compliance; Dynamic Sheer Rheometer (DSR); elastomer identification; Multiple Stress Creep and Recovery (MSCR) Test; percent recovery; polymer modification; elastic behavior. 1This full standard was first published in 2018. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
