AASHTO TP 134-19 pdf free download

AASHTO TP 134-19 pdf free download.Stress Sweep Rutting (SSR) Test Using Asphalt Mixture Performance Tester (AMPT).
TERMINOLOGY
confining pressure—stress applied to all surfaces in a confined test.
3.2. deviatoric stress—difference between the vertical stress and the confining pressure.
3.3. loading hlock—200 repetitions of loading cycles.
3.4. permanent strain—non-recovered strain in a repeated load test.
3.5. repeated load cycle—loading of 0.4 s followed by a 3.6-s rest period at the high test temperature (i’ll) and loading of 0.4 s followed by a 1.6-s rest period at the low test temperature (71).
3.6. shift model—permanent strain model that can predict permanent strain under various load times, deviatoric stress levels, and temperatures.
3.7. vertical stress—total vertical stress, including applied stress and confining pressure.
SUMMARY OF THE TEST METHOD
The SSR test is conducted at two test temperatures. referred to as T,, (the high temperature) and 71
(the low temperature). and under constant confining pressure of 69 kPa (10 psi). with three
200-cycle loading blocks of three deviatoric stress levels.
4.2. The load pulse is 0.4 s for each cycle. The rest period is dependent on the test temperature. The permanent axial deformation that occurs at each load cycle is measured using actuator displacement.
SIGNIFICANCE AND USE
The SSR test measures permanent deformation characteristics of asphalt mixtures as a function of deviatoric stress. loading time, and temperature. The results from two SSR tests at each of the high and low temperatures can be used to develop the shift model. The shift model has been incorporated into the pavement performance prediction program, FIexPAVE , to predict the permanent deformation of asphalt layers under various deviatoric stress levels, loading times, and temperatures as a function of pavement depth and time. The SSR test results also can be employed as part of a performance-engineered mix design for asphalt mixtures.
5.2. The shift model is based on the permanent deformation behavior of an asphalt mixture in the primary and secondary regions. If tertiary flow occurs during the SSR test, the applicability of the shift model to the test results depends on when the tertiary flow occurs. If the tertiary flow occurs during the first or second loading blocks, the test results should not be used to develop the shift model. If the tertiary flow occurs toward the end of the third loading block, the test results can be used to develop the shift model.
APPARATUS
Specimen Fabrication Equipment—Equipment used to fabricate SSR test specimens as described in R 83.
6.2. Asphalt Mixwre Performance Tester (‘AMPT,i—Dynamic testing apparatus that meets the requirements of Equipment Specification for the Simple Performance Test System, Version 3.0.
6.3. C’oiditioning chamber—Environmental chamber that is used to condition the test specimens to the desired test temperature. The environmental chamber shall he able to control the temperature of the specimen over a temperature range from 4 to 70°C (39 to 158°F) to an accuracy of ±0.5°C (±0.9°F). The chamber shall be large enough to accommodate at least Iwo specimens to be tested, plus a dummy specimen with a temperature sensor mounted in the center for temperature verification.
Note ‘1—The temperature range required for the conditioning chamber is a function of the anticipated test temperature. The temperature control range provided in this section is intended to be inclusive of all areas of the U.S. In many climatic regions. it may not be necessary to have equipment capable of controlling the temperature up 1070°C (158°F).AASHTO TP 134-19 pdf download.