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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Loading Device—The test system shall include a closed-loop, computer aashgo 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.
This standard does not purport to address all of the safety concerns associated with its use.
The area under the curve represents the cumulative dissipated energy. Miscellaneous Apparatus and Materials—A suitable saw for cutting the beams and a mechanism for setting proper clamp spacing. When the specimen has experienced greater than 50 percent reduction in stiffness, terminate the test.
An environmental chamber is not required if the temperature of the surrounding environment can be maintained within the specified limits. Users of this practice are cautioned that compliance with Specification D alone does not completely ensure reliable results. 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.
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Maximum Tensile Stress Pa: Duplication is a violation of applicable law. Prepare a plot of stiffness versus load cycles as shown in Figure 7.
Referenced Documents purchase separately Azshto documents listed below are referenced within the subject standard but are not provided as part of the standard. 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. Bias—The research required to establish the bias of this method has not been conducted.
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This stiffness is an estimate of the initial stiffness, which is used as a reference for determining specimen failure. 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. These notes and footnotes excluding those in tables and figures shall not be considered as requirements of the standard.
Note 7—See E 29 for information on determination of significant figures in calculations. Please copy and paste this embed script to where you want to embed Embed Script. T32 2 illustrates a nut epoxied to the neutral axis of the specimen.
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. Aashto performance of HMA can be more accurately predicted when these properties are known.
The constant A represents the aastho stiffness. Observe standard laboratory aaashto 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. Saw at least 6 mm from both sides of each test specimen to provide parallel saw-cut surfaces to eliminate high air void sections on the specimen surface. Environmental Chamber Optional —The environmental chamber shall enclose the entire specimen and maintain the specimen at Specimen Measurement—Measure the height and width of the specimen to the nearest 0.
Note 3—Selection of load cycle intervals at which test results are computed and t32 may be limited by the amount of memory available for storing data. Compacted specimens are suitable for volumetric and physical property testing.
AASHTO T, Test equipment Controls
However, the standard compactive effort may not reproduce the air voids of roadway specimens measured according to T Figure 7 presents a typical plot of stiffness versus load cycles. Determine the average of the three measurements for each dimension and record the averages to the nearest 0. No other units of measurement are included in this standard. Avoid applying epoxy such that it fills the center of the nut.