AASHTO TP 131:18(2020) Proposed Standard Test Method for Determining the Dynamic Modulus of Asphalt Mixtures Using the Indirect Tension Test.
7.1. This practice and associated standards involve handling of hot asphalt binder, aggregates and asphalt mixtures. It also includes the use of sawing and coring machinery and servo-hydraulic testing equipment. Use standard safety precautions, equipment. and clothing when handling hot materials and operating machinery.
8.1. Items associated with this practice that require calibration are included in the documents referenced in Section 2.2. Refer to the pertinent section of the referenced documents for information concerning calibration.
9. 1. Test Specimen Fabrication
9.1.1. Testing shall be performed on 150 ± 9 mm diameter by 38 to 50 mm thick test specimens fabricated in accordance with AASHTO PP 95. Preparation of Indirect Tension Performance Test Specimens.
9.1.2. Prepare at least three test specimens to the target air void content and aging condition in accordance with AASHTO PP 95, Preparation of Indirect Tension Performance Test Specimens. Note 1–A reasonable air void tolerance for test specimen fabrication is ± 0.5 percent.
9.2. Test Specim en bis!run en lalion
9.2.1. Attach the gauge points to the specimen with epoxy using the alignment device mentioned in Section 6.7. The recommended gauge length is 101.6 mm ± 1.0 mm measured center to center of the gauge points. The gauge length is centered on the intersection of the diametral lines drawn according to AASHTO PP XX-XX Preparation of Indirect Tension Performance Test Specimens, Section 10.7. Attach the gauge points on the horizontal and vertical lines. Repeat the process on the opposing cut face of the specimen. Allow the epoxy to harden according to manufacturer’s specifications.
Note 2—For open-graded asphalt mixtures with large surface voids, prior to gluing the gauge points, examine the locations where gauge points would be placed before gluing to avoid large surface voids under the gauge points. Follow the instructions in Section 10.7.2 of PP 95, Preparation of Indirect Tension PerfOrmance Test Specimens to avoid large surface voids under the gauge points.
9.2.2. Attach LVDT core rods and heads.
9.3. Alignment of Loud Guide Device—performed when initially setting up the machine or when the difference of the horizontal or vertical LVDT strains on both faces are greater than 20 ml crostrains.
9.3.1. Once the LGD has been placed in the chamber, the device needs to be aligned. To align the device, use a stiff specimen (Section 6.8) which has been instrumented according to Section 9.2.
9.3.2. Place the stiff specimen on its edge and align the vertical line with center lines marked on the LGD. Apply a small seating load of 0.05 kN to hold the specimen while aligning.AASHTO TP 131 pdf download.