How to Use an Asphalt Penetration Tester

　　Instructions for using the asphalt penetration tester:
　　1. Heat and melt the pre-dewatered sample. The heating temperature must not exceed 90°C above the sample’s estimated softening point, and the heating duration must not exceed 30 minutes. After thorough stirring and sieving, pour the melted sample into a sample dish. The depth of the sample in the dish should be at least about 10 mm greater than the expected penetration value. Place the dish in a room at a temperature of 15–39°C and allow it to cool for 1 hour. During cooling, ensure that no dust falls into the sample.
　　2. Immerse the sample dish into a water tank filled with clean water, and maintain it at a constant temperature for 1 to 1.5 hours, keeping the water temperature at 25 ± 0.5℃. The water level should be at least 25 mm above the surface of the sample.
　　3. Adjust the asphalt penetration tester so that it is level (if necessary, adjust the weight of the additional weights). Press down the release button with your hand and lift the standard needle rod.
　　4. After the sample container has been kept warm for 1–1.5 hours, remove it and place it into a flat-bottomed thermal-insulation container whose water temperature is strictly maintained at 25℃. The height of the water layer above the sample surface should be no less than 10 mm. Place the thermal-insulation container onto the circular working platform of the penetration tester, and adjust the working platform so that the sample surface just touches the needle tip (if the adjustment of the working platform is insufficient, use the adjusting nut to fine-tune the linkage accordingly).
　　5. Set the time switch to the desired duration for the test specimen (5 seconds or 60 seconds). Press the start button; the electromagnet will engage, allowing the standard needle to freely penetrate the specimen until the red light comes on. At this point, the standard needle has been penetrating the specimen for either 5 seconds or 60 seconds, and the electromagnet’s release mechanism will automatically lock the needle rod in place, preventing it from continuing to descend. The depth value displayed at this moment is the penetration depth.
　　6. The same sample must be tested repeatedly at least three times. Each penetration point must be spaced at least 10 mm apart from the other penetration points as well as from the edge of the sample dish. The average of the results obtained from these individual tests shall be taken as the final test result for this sample.
　　7. Before each experiment, the water temperature in the保温皿 should be checked and adjusted. After the experiment, the standard needle should be removed and wiped clean with cotton or cloth soaked in a solvent (trichloroethylene), then dried thoroughly with cotton or cloth.