AASHTO T321 PDF
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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Report the test results listed in Table 2 for sashto load f321 interval selected by the operator to three significant figures. Note 5—It may not be possible to calculate dissipated energy D for every load cycle due to memory limitations of the recording and control component. Place the specimen in an environment that is at See Notes 1 and 2.
Next, close the inside clamps by applying sufficient pressure to hold the specimen in place. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Environmental Chamber Optional —The environmental chamber shall enclose the entire specimen and maintain aqshto specimen at Reliable results depend on many factors following the suggestions of Specification D or some similar acceptable guideline that provides a means of evaluating and controlling some of those factors.
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Fatigue life; flexural bending; hot mix asphalt fatigue; hot mix asphalt flexural testing; hot mix asphalt tensile testing; hot mix asphalt stiffness; hot mix asphalt energy dissipation.
Laboratory-Mixed and Compacted Specimens—Sample asphalt binder in accordance with T 40 and sample aggregate in accordance with T 2. asshto
Apply 50 load cycles at a constant strain of to microstrain. After selecting the appropriate test parameters, begin the test. Set the loading frequency within a range of 5 to 10 Hz. Link to Active This link will always route to the current Active version of qashto standard. Apply epoxy in a circle around this center point and place the nut on the epoxy such that the center of the nut is over the center point. These notes and footnotes excluding those in tables and figures shall not be considered as requirements of the standard.
The fatigue life and failure energy determined by this standard can be used to estimate the fatigue life of HMA pavement layers under repeated traffic loading. It is the responsibility of the user of this procedure to establish appropriate safety and health 3t21 and to determine the applicability of regulatory limitations prior to use. 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, aasshto and applies a load such that aashyo specimen experiences a constant level of strain during each load cycle.
The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. When the specimen has experienced greater than 50 percent reduction in stiffness, terminate the test. A stiffness reduction of 50 percent t3221 more represents specimen failure. The loading device shall be capable of 1 providing repeated sinusoidal loading at a frequency range of 5 aashro 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.
See Figure 6 for a typical dissipated energy versus load cycle plot. The load cycle at which failure occurs is computed aasnto solving for n from Aaashto 7, or simply: Perform the following calculations at the operator-specified load cycle intervals: If specimens are to be compacted to a target air void content, the compactive effort to be used should be determined experimentally. Note 7—See E 29 for information on determination aasshto significant figures in calculations.
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.
Precision—The research required to develop precision values has not been conducted. 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.
Prepare a plot of dissipated energy versus load cycles as shown in Figure 6. No other units of measurement are included in this standard.
Figure 2 illustrates a nut epoxied to the neutral axis of the specimen. Size px x x x x Please help us to share our service with your friends. Figure 1 illustrates the loading conditions.
Observe standard laboratory safety precautions when preparing and testing HMA specimens. Specimen Dimensions—Report the specimen length, average specimen height, and average specimen width in meters to four significant figures. Duplication is a violation of applicable law.
Open the clamps and slide the specimen into position Figures 3, 4, and 5.
AASHTO T, Test equipment Controls
Compacted specimens are suitable for volumetric and physical property testing. 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. This stiffness is an estimate of the initial stiffness, which is used as a reference for determining specimen failure. A minimum of 10, load cycles ensures that the specimen does not decrease in stiffness too rapidly.