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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Avoid applying epoxy such that it fills the center sashto the nut. Environmental Chamber Optional —The environmental chamber shall enclose the entire specimen and maintain the specimen at However, the standard compactive effort may not reproduce the aqshto voids of roadway specimens measured according to T Size px x x x x Set the loading frequency within a range of 5 to 10 Hz. Agencies that meet the criteria of Specification D are generally considered capable of competent and objective testing, sampling, inspection, etc.

It is the responsibility of the user of this procedure t231 establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use. 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. The total dissipated energy to failure is summarized as part of the output. Apply 50 load cycles at a constant strain of aashho microstrain.

The quality of the results produced by this standard sashto dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance aasjto the equipment used. Figure 1 illustrates the loading conditions. This standard provides procedures for determining the fatigue life and fatigue energy of mm long by 50 mm thick by 63 mm wide hot mix asphalt HMA beam specimens sawed from laboratory or field compacted HMA and subjected to repeated flexural bending until failure.

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. The performance of HMA can be more accurately predicted when these properties are known.


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.

A stiffness reduction of 50 percent or more represents specimen failure. Duplication is a violation of applicable law. No other units of measurement are included in this standard. Referenced Documents purchase separately The documents zashto below are referenced within the subject standard but are not provided as part aaashto the standard.

AASHTO T, Test equipment Controls

If specimens are to be compacted to a target air void content, the compactive effort to be used should be determined experimentally. Maximum Tensile Stress Pa: Report the initial flexural stiffness in pascals.

The area under the curve represents the cumulative dissipated energy. 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.

Report the cycles to aashtoo. These notes and footnotes excluding those aaxhto tables and figures shall not be considered as requirements of the standard.

Laboratory-Mixed and Compacted Specimens—Sample asphalt binder in accordance with T 40 and sample aggregate in accordance with T 2. When the specimen has experienced greater than 50 percent reduction in stiffness, terminate the test.

r321 Bias—The research required to establish the bias of this method 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.

Note 7—See E 29 for information on determination of significant figures in calculations. Determine the average of the three measurements for each dimension and record the averages to the nearest 0.

Figure 2 illustrates a nut epoxied to the neutral axis of the specimen. Perform the following calculations at the operator-specified load cycle intervals: Report the average test temperature to the nearest 0. Specimen Dimensions—Report the specimen length, average specimen height, and average specimen width in meters to four significant figures.



For loading devices that require a glued nut for deformation measurement, a screw, nut aashtk 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.

The loading asshto 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. Allow the epoxy to cure before moving the specimen.

Please help us to share our service with your friends. Next, close the inside clamps by applying sufficient pressure to hold the specimen in place. Link to Active This link will always route t312 the current Active version of the standard.

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 h321 during each load cycle.

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See Notes 1 and 2. We need your help! Cycles to Failure—Failure is defined as the point at which the specimen stiffness is reduced to 50 percent of the initial stiffness. 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.

Use the jig to ensure proper horizontal spacing of the clamps, mm center-to-center. Note 1—The type of compaction device may influence the test results.