AASHTO T 321-17 pdf free download

AASHTO T 321-17 pdf free download.Determining the Fatigue Life of Compacted Asphalt Mixtures Subjected to Repeated Flexural Bending.
3. TERMINOLOGY 3.1. Definition: . 3.1.1. failure point- -the load cycle at which a peak occurs in the plot of stiffness multiplied by load cycles versus load cycles, which is indicative of the formation of a crack in the specimen. 4. SIGNIFICANCE AND USE 4.1. The fatigue life and failure energy determined by this standard can be used to estimate the fatigue life of asphalt mixture pavement layers under repeated traffic loading. The performance of asphalt mixtures can be more accurately predicted when these properties are known. 5. APPARATUS 5.1. Test System- The test system shall consist of a loading device, an environmental chamber (optional), and a control and data acquisition system. The test system shall meet the minimum requirements specified in Table 1.5.1.1. Loading Device- The test system shall include a closed-loop, computer controlled loading component that, during each load cycle in response to commands from the data processing and control component, adjusts and applies a load such that the specimen experiences a constant level of strain during each load cycle. The loading device shall be capable of (1) providing repeated sinusoidal loading at a frequency range of 5 to 10 Hz; (2) subjecting specimens to four-point bending with free rotation and horizontal translation at all load and reaction points; and (3) forcing the specimen back to its original position (i.e., zero deflection) at the end of each load pulse. (Figure 1 illustrates the loading conditions.) 5.1.2. Environmental Chamber (Optional)- The environmental chamber shall enclose the entire specimen and maintain the specimen at the test temperature土0.5°C during testing. An environmental chamber is not required if the temperature of the surrounding environment can be maintained within the specified limits. 5.1.3. Control and Data Acquisition System- During each load cycle, the control and data acquisition system shall be capable of measuring the deflction of the beam specimen, computing the strain in the specimen, and adjusting the load applied by the loading device such that the specimen experiences a constant level of strain on each load cycle. In addition, it shall be capable of recording load cycles, applied loads, and beam deflections and computing and recording the maximum tensile stress, maximum tensile strain, phase angle, stiffiness, dissipated energy, and cumulative dissipated energy at load cycle intervals specified by the user. 5.2. Miscellaneous Apparatus and Materials- A suitable saw for cutting the beams and a mechanism for setting proper clamp spacing. For loading devices that require a glued nut for deformation measurement, a screw, nut (suggested size M 8 by 1) and block assembly for referencing the linear variable differential transducer (LVDT) to the neutral axis of the specimen, and epoxy for attaching a target to the specimen at the neutral axis are also needed. .7. SAMPLING AND SPECIMEN PREPARATION 7.1. Laboratory-Mixed and Compacted Specimens- Sample asphalt binder in accordance with R 66 and sample aggregate in accordance with R 90. Prepare three replicate asphalt mixture beam specimens, from slab(s) or beam(s) compacted in accordance with PP 3 or T 247. Note 1- -The type of compaction device may influence the test results. It is recommended to cut beams from a large slab compacted by a vibratory roller. Note 2- Normally, test specimens are compacted using a standard compactive effort. However, the standard compactive effort may not reproduce the air voids of roadway specimens measured according to T 269. If specimens are to be compacted to a target air void content, the compactive effort to be used should be determined experimentally. Note 3- -This standard is suitable for testing asphalt mixtures with a nominal size of 19 mm or smaller. Care should be taken when interpreting results obtained from specimens that do not meet this requirement.AASHTO T 321-17  pdf download.