The penetration test of bitumen is an important method to evaluate its temperature sensitivity and fluidity. This detection method is suitable for the residues of road petroleum asphalt, polymer modified asphalt and liquid petroleum asphalt distilled or emulsified asphalt. According to the national standard T0604-2011, the test was carried out in a standard environment of 25°C, and the main equipment used included a needle penetratIon Meter for automatic timing, a standard needle and a sample container. This article describes the test preparation, test steps and result calculations in detail, aiming to provide a systematic reference for asphalt testing.
Test preparation
The first step in conducting a bitumen penetration test is the preparation of the sample. Inject the asphalt sample into the sample container to ensure that the sample height exceeds the expected penetration value by 10 mm. Samples should be cooled at room temperature for 1.5 h and then transferred to a thermostatic sink and kept at 25 °C for 2 h. This process ensures that the temperature of the asphalt sample is uniform and that test errors are avoided.
In the preparation of the test equipment, it is necessary to adjust the penetratIon Meter to the level to ensure that the needle connecting rod and guide rail are free of interference. Standard needles should be cleaned and dried with trichloroethylene or other appropriate solvents to ensure a clean surface that would not affect the test results.
Test Steps
Place the sample container on the platform of the needle penetratIon Meter and slowly lower the needle connecting rod to ensure that the needle tip is in contact with the asphalt surface. Use a reflector or light to observe contact.
Start the test, press the release button, the timing and the standard needle fall into the asphalt start at the same time, and stop automatically after 5 seconds.
Reads the displacement gauge or dial hand to the nearest 0.1 mm. Each sample should be tested in parallel at least three times to ensure that the distance between the test points and the edge of the sample dish is not less than 10mm.
When testing bitumen samples with penetration greater than 200, use at least three standard needles and leave the needles in the sample after each test until all parallel tests have been completed.
When measuring the penetration index, it is necessary to measure the penetration under multiple temperature conditions such as 15°C, 25°C, and 30°C.
Data calculation and reporting
Test results are reported in 0.1 mm increments and include penetration at standard temperature (25°C) as well as penetration index, equivalent softening point and equivalent brittle point at different temperature conditions. During the calculation, regression analysis or nomogram method can be used to perform linear regression according to the penetration values at different temperatures to determine the penetration temperature index and correlation.
In the report, the penetration values at the standard temperature of the test and other test temperatures should be included, as well as the indicators derived from the calculation method. The validity of the test results depends on the margin of error for repeatability and reproducibility and must meet the requirements of the standard.
summary
Asphalt penetration testing is a key test method that provides engineers with important performance metrics by accurately measuring the flow and temperature sensitivity of asphalt at different temperatures. These indicators not only help to evaluate the suitability of asphalt, but also guide the selection and application of materials in actual construction. Through standardized testing process and data analysis, the accuracy and reliability of asphalt test results are ensured, and a scientific basis is provided for road construction and maintenance.
