AASHTO T321 PDF
February 4, 2021 | by admin
AASHTO T Standard Method of Test for Determining the Fatigue Life of Compacted Asphalt Mixtures Subjected to Repeated Flexural Bending. standard . AASHTO T/TP8 is a Test Standard for Determining the Fatigue Life of Compacted Hot-Mix Asphalt (HMA) Subjected to Repeated Flexural Bending. AASHTO T (AASHTO, ) and the European Standard (EN , ). When evaluating fatigue resistance through four point bending beam.
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Laboratory-Mixed and Compacted Specimens—Sample asphalt binder in accordance with T 40 and sample aggregate in accordance with T 2. Select a sashto level strain level such that the specimen will undergo a minimum of 10, load cycles before its stiffness is reduced to aaashto percent or less of the initial stiffness.
Note 3—Selection of load cycle intervals at which test results are computed and recorded may be limited by the amount of memory available for storing data. Report the cycles to failure.
A minimum of 10, load cycles ensures that the specimen does not decrease in stiffness too rapidly. Open the clamps and slide the t3211 into position Figures 3, 4, and 5.
Figure 1 illustrates the loading conditions. Note 7—See E 29 for information on determination of significant figures in calculations.
Miscellaneous Apparatus and Materials—A suitable saw for cutting awshto beams and a mechanism for setting proper clamp aazhto. See Figure 6 for a typical dissipated energy versus load cycle plot. An environmental chamber is not required if the temperature of the surrounding environment can be maintained within the specified limits. When the specimen and clamps are in the proper positions, close the outside clamps by applying sufficient pressure to aashho the specimen in place.
Compacted specimens are suitable for volumetric and physical property testing. Environmental Chamber Optional —The environmental chamber shall enclose the entire specimen and maintain the specimen at The total dissipated energy to failure is summarized as part of the output. Activate the recording and control components so that the test results at the selected load cycle intervals are monitored and recorded, ensuring that the test system is operating properly.
Report the test results listed in Table 2 for each load cycle interval selected by the operator to three significant figures. This standard may involve hazardous materials, operations, and equipment. However, the standard compactive effort may not reproduce the air voids of roadway specimens measured according to T Figure 2 illustrates a nut epoxied to the neutral axis of the specimen. Specimen Measurement—Measure the height and width of the specimen to the nearest 0.
The constant A represents the initial stiffness. Initial Stiffness Pa —The initial stiffness is determined by plotting stiffness S against load cycles n and best-fitting the data to an exponential function of the form shown in Equation 7.
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Place the specimen in an environment that is at Determine the specimen stiffness at the 50th load cycle. Attach the LVDT block to the specimen by screwing the screw into the nut epoxied on the specimen.
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Hot Mix Asphalt Description—Report the binder type, binder content, aggregate gradation, awshto air void percentage. 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, stiffness, dissipated energy, and cumulative dissipated energy at load cycle intervals specified by the user.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. After selecting the appropriate test parameters, begin the test.
See Notes 1 and 2. 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 the nut to the specimen are also needed.
aashto If specimens are to be compacted to a target air void content, the compactive effort to be used should be determined experimentally. Agencies that meet the criteria of Specification D are generally considered capable of competent and objective testing, sampling, inspection, etc.
Use the jig to ensure proper horizontal spacing of the clamps, mm center-to-center. This stiffness is an estimate of the initial stiffness, which is used as a reference for determining specimen failure. 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.
Apply epoxy in a circle around this center point and place the nut aasyto the epoxy such that the center of the nut is over the center point.