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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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Place the specimen in an environment that is aasshto Maximum Tensile Stress Pa: Bias—The research aqshto to establish the bias of this method has not been conducted. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. Agencies that meet the criteria of Specification D are generally considered capable of competent and objective testing, sampling, inspection, etc. Initial Stiffness Pa —The initial stiffness is determined by plotting stiffness S against load cycles n and best-fitting the data to an exponential aasyto of the form shown in Equation 7.

It is the responsibility of the user of this procedure to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.

AASHTO T, Test equipment Controls

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. However, the standard compactive effort may not reproduce the air voids of roadway specimens measured according to T Figure 1 illustrates the loading conditions.

Select a deflection level strain level such that the specimen will undergo a minimum of 10, load cycles before its stiffness is reduced to 50 percent or less of the initial stiffness. No other units of measurement are included in this standard. Link to Active This link will always route to the current Active version of the standard.

T_321-07_2011

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.

Open the clamps and slide the specimen into position Figures 3, 4, and 5. This practice should not be used for acceptance or rejection of a material or for purchasing purposes.

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Miscellaneous Apparatus and Materials—A suitable saw for cutting the beams and a mechanism for setting proper clamp spacing.

Perform the following calculations at the operator-specified load cycle intervals: Environmental Chamber Optional —The environmental chamber shall enclose the entire specimen and maintain the specimen at An environmental chamber is not required if the temperature of the surrounding environment can be maintained within the specified limits. 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.

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. Specimen Dimensions—Report the specimen length, average specimen height, and average specimen width in meters to four significant figures.

Control and Data Acquisition System—During each load cycle, the control and data acquisition system shall be capable of measuring the deflection 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.

After selecting the appropriate test parameters, begin the test.

Please fill this form, we will try to respond as soon as possible. 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 aashtl the specimen experiences a constant level of strain during each load cycle.

Please copy and paste this embed script to where you want to embed Embed Script. See Notes 1 and 2. Attach the LVDT block to the specimen by screwing the screw into the nut epoxied on the specimen.

When the specimen has experienced greater than 50 percent reduction in stiffness, terminate the test. It is recommended to cut beams from a large slab compacted by a vibratory roller. Report the test results listed in Table 2 for each load cycle interval selected by the operator to three significant figures. Prepare a plot of stiffness versus load cycles as shown xashto Figure 7.

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Apply 50 load cycles at a aashot strain of to microstrain. Size px x x x x Please help us to share our service with your friends.

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. Set the loading frequency within a range of 5 to 10 Hz. When the specimen and clamps are in the proper positions, close the outside clamps by applying sufficient pressure to hold the specimen in place.

Avoid applying epoxy such that it fills the center of the nut. Use the jig to ensure proper horizontal spacing of the clamps, mm center-to-center. Determine the average of the three measurements for each dimension and record the averages to the nearest 0. 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. 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.

The area under the curve represents the cumulative dissipated energy. Figure 2 illustrates a nut epoxied to the neutral axis of the specimen. 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.

These notes and footnotes excluding those in tables and figures shall not be considered as requirements of the standard. For loading devices y321 require gluing a nut for deformation measurement, these cut surfaces provide smooth surfaces for mounting the measurement gauges.

This standard may involve hazardous materials, operations, aashtk equipment. A stiffness reduction of 50 percent or more represents specimen failure. This standard does not purport to address all of the safety concerns associated with its use.

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