AASHTO TP 101-12 pdf free download
AASHTO TP 101-12 pdf free download.EstimatingI Fatigue Resistance . of Asphalt Binders Using the Linear Amplitude Sweep.
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 he further aged using R 28 (PAV) prior to testing in order to simulate long-term aging of asphalt pavements. A sample is prepared 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 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 resist tätigue 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 amount 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) followed by R 28 (PAV) for long- term performance.
7.2. Sample Preparation—The 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 the rheological properties in the DSR on PAV residue as specified in M 320.
7.3. Test Protocol—Two 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 measure the damage characteristics of the material.
7.3.1. Determination of “Alpha “Parameter—In order to perform the damage analysis, information regarding the undamaged material properties (represented by the parameter a) must be determined. The frequency sweep procedure outlined in Section 7.3. 1 . I is used to determine the alpha parameter.
7.3.1 .1. Frequency Sweep—Frequency 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 frequencies. For this test method, the frequency sweep test is selected from the DSR manufacturer’s 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):Complex shear modulus [|G*|, Pa] and phase angle [δ, degrees] are recorded at each frequency, as shown in Figure 1.11. KEYWORDS 11.1. Asphalt binder; continuum damage; DSR; fatigue; performance grading. 12. REFERENCES 12.1. Kim, Y, H.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.755 -788. 12.2. Hintz, C., R. Velasquez, C. Johnson, and H. Bahia.“Modification and validation 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, W ashington, DC, 2011, pp.96- -106.AASHTO TP 101-12 pdf download.
