New Product Release: Asphalt Direct Tensile Tester (Fracture Performance)

New Product Release: Asphalt Direct Tensile Tester (Fracture Performance)

Recently, our company has launched a new asphalt direct tensile tester (fracture performance). Below is a detailed introduction of this product:

1、 Product Introduction

The Direct Tensile Test (DTT) for asphalt is specifically designed to evaluate the stiffness and fatigue characteristics of asphalt binders under low temperature conditions. Designed and manufactured by Hebei Tianqi Xingzi Testing Equipment Co., Ltd. in accordance with the requirements of T 0631-1993 "Asphalt Floatation Test" specified in the industry standard JTG E20-2011 "Test Code for Asphalt and Asphalt Mixtures in Highway Engineering" of the People's Republic of China. To provide accurate and reproducible experimental results for ZJ, the following key features have been incorporated into the system design. The asphalt direct tensile tester adopts a high stiffness loading frame and testing head, which almost completely avoids friction and errors caused by system flexibility. The test head is driven by a high-performance Exlar actuator, which can provide Z-large dynamic response and sensitivity, while the gear motor drive system does not produce clearance or shutdown. All key sensors and load cell components are isolated from the liquid bath, ensuring a safe and stable environment. Linear sensors are installed diagonally on the sample to provide accurate strain rate and position information for ZJ.

2、 Data collection

Based on Windows software, it operates fully automatically and requires almost no human intervention. It is specifically designed to complete the low-temperature thermal performance test of AASHTO TP 314 asphalt binder, and can control and record all required parameters. During the experiment, the experimental data can be displayed on the computer screen and stored on the disk simultaneously. The data can be easily exported to other application software, such as Microsoft Excel. Both data acquisition and closed-loop control use 16 bit digital processors to ensure accuracy and sensitivity.

3、 Performance characteristics

1. Complete set of software packages

2. 16 bit real-time data acquisition

3. Automatic or manual operation

4. Conventional and research modes

5. Closed-loop drive control

6. High precision linear servo motor

7. Computer-controlled liquid bath

8. Refrigerator optional

4、 Technical specifications

1. Test temperature: from room temperature to -40 ℃

2. Temperature control accuracy: ± 0.1 ℃

3. Output control: A. Stepper motor; B、 Heating wire (1kW); C、 Compressor x 2 (1kW x 2)

4. Display parameters: A. Temperature display; B、 Tension display; C、 Displacement display

5. Communication interface: Three core serial port

6. Working power supply: AC (220 ± 10%) V, 50Hz

7. Power consumption of the whole machine: not exceeding 3500W

8. Applicable ambient temperature: (20-25) ℃

9. Relative humidity: ≤ 80%

10. Dimensions (mm): 920 × 740 × 930 (length × width × height)

4、 Operation steps

1. Preparation work

1.1 Prepare the sample according to the method specified in Test Procedure T0602. Set the cold bath at the required test temperature and stabilize it within the range of ± 0.1 ℃. Heat the asphalt sample until it is in an easy to pour state, but the heating temperature should not exceed 135 ℃; For modified asphalt or aged asphalt, the flowability during pouring should be ensured, and the heating temperature should not exceed 165 ℃. The heating time should be as short as possible. To ensure uniformity, slight mixing can be used. During mixing, care should be taken not to let bubbles get trapped in the asphalt. 1.2 Apply isolation agent to the two inner templates of the test mold, so that a thin layer of isolation agent is evenly distributed on the metal surface without any exposed parts. Place a pre cut isolation paper on the pallet of the trial mold, place the side template on the isolation paper, place the end mold on both ends of the trial mold, and place the other side mold on the bottom plate to form a complete trial mold assembly. Place the trial module on a flat ceramic tile and keep it in a 163 ℃ oven for 30 minutes. 1.3 Remove the tiles and test molds from the oven, place them on a flat surface, and then pour them into shape in one go. The level of hot asphalt should be slightly higher than the surface of the test mold for easy adjustment after cooling. 1.4 Cool the test mold naturally at room temperature for about 60 minutes, and then use a hot scraper to scrape off excess asphalt on the top. Note that the surface of the repaired asphalt specimen should be flat. 1.5 Place the molded specimen in a 0 ℃ refrigerator or cold bath for about 5 minutes, and carefully demold it after the specimen has hardened. Attention: During the demolding process, twisting or bending of the specimen should be avoided, otherwise it will affect the test results.

2. Experimental steps

2.1 Prepare 6 test specimens as described in section 1. 2.2 Set the cold bath temperature to the test temperature and stabilize it at ± 0.2 ℃; Then adjust the force value to zero according to the program. 2.3 Place the specimen in a constant temperature cold bath for curing for 60 minutes ± 5 minutes; Then use Z to clamp the specimen and install it on the pin. Note that the holes of the trial mold match the upper and lower axes of the sample holder. After the specimen is in place, check whether it is placed steadily. Note that the force value displayed on the computer at this time, T., is 0.1N, otherwise the cause needs to be checked. Set the stretching rate to 1mm/min. Reset the displacement and strain to zero and start the experiment. 2.6 Stop the test when the specimen breaks or the strain exceeds 10%, and remove the specimen and asphalt fragments. When the load reaches its peak, the specimen suddenly fractures and is recorded as brittle failure, which is the Z-strain under Z-stress state; If the specimen continues to deform without breaking when subjected to high stress Z, the failure strain is recorded as the strain corresponding to the high stress Z; When the strain exceeds 10%, there is no need to continue the test. Record the failure strain as "greater than 10%", and the asphalt meets the requirements of the relevant standard test temperature. 2.8 Record the failure load and the failure shape of the specimen. If the specimen fails at the neck, record the failure data and indicate it at the neck; if it does not break by more than 10%, record the load at 10% elongation and indicate that the specimen has not broken. 2.9 Repeat steps 2.2-2.7 until 6 specimens have been tested. 2.10 The plastic end mold can be reused, and after the test is completed, it should be carefully cleaned. Soak the plastic end mold in a solvent, then wipe it clean with a soft cloth, and use clean soap or detergent Q to remove the oil film left by the solvent on the bonding surface.

5、 Result calculation

1. Calculate the failure stress of each specimen according to equation (T0629-1).

σf=Pf/A (T0629-1)；

In the formula: σ f - failure stress (MPa);

Pf - destructive load (N);

A - Initial cross-sectional area of the specimen (mm2).

2. Calculate the failure strain of each specimen according to equation (T0629-2).

εf=δf/L (T0629-2)；

In the formula: ε f - failure strain (mm/mm);

δ f - elongation value at failure (mm);

L - Y-effect tensile length of specimen (mm).

6、 Preparation of experimental report

Remove two specimens with low failure stress Z from the same test result. If two or more specimens have the same failure stress but different strains, remove the two specimens with lower failure strain values. Use the test results of the remaining four specimens to calculate the average and standard deviation of the failure stress and failure strain.