Asphalt ductility test is a key method to evaluate the fluidity of materials such as road petroleum asphalt and polymer modified asphalt. The test is performed at a specific temperature, using a ductility meter and a Thermostatic Water Bath, which ensures accurate stretching of the specimen. The testing process includes sample preparation, cooling, and measurement, with multiple parallel tests to obtain reliable ductility values to guide the engineering application and quality control of asphalt.
The ductility testing method of asphalt is mainly used to determine different types of asphalt materials, including road petroleum asphalt, polymer modified asphalt, liquid petroleum asphalt distillation residue and emulsified asphalt evaporation residue. Ductility is a key indicator to evaluate the fluidity of asphalt under temperature change conditions, and the test temperature is usually 25°C, 15°C, 10°C or 5°C to adapt to different engineering needs.
The equipment required to perform the ductility test includes a ductility meter, a Thermostatic Water Bath, and a thermometer. The ductility meter should have the function of automatic temperature control and speed control, and its measurement length should not be greater than 150cm. In addition, the temperature control accuracy of the thermostatic tank needs to reach 0.1°C to ensure the accuracy and repeatability of the test. The release agent used is a mixture of glycerol and talc to reduce the adhesion between the specimen and the mold.
Release agent treatment – glycerin is evenly mixed with talcum powder and applied to the inside of the tryout.
Specimen Preparation – Prepare asphalt specimens in accordance with the relevant standards to ensure that there are no bubbles when injected into the tryout.
Cooling & Scraping – After cooling the specimen at room temperature for at least 1.5 hours, use a thermal scraper to scrape the surface of the specimen.
Keep warm – put the tryout mold in a constant temperature sink and keep it warm for 1.5 hours.
Specimen Placement – Put the specimen and the base plate into the sink of the ductometer and adjust the water level to 25mm below the surface of the specimen.
Start the instrument – turn on the ductility meter and observe the extension of the asphalt to ensure that the water temperature is maintained within the set range.
Record the results - after the specimen is broken, read the ductility value, under normal circumstances, the specimen should be cone-pointed, and the cross-section should be close to zero.
At least three parallel tests are required. According to the measured results, if they are all larger than 100cm, they are reported as "> 100cm". If the result is less than 100cm, the difference between the maximum and minimum values and the average value will be judged, and the test will be re-performed as required.
Through the detection of asphalt ductility, it can not only effectively evaluate its performance under different temperature conditions, but also provide a scientific basis for the use and modification of asphalt. With the continuous progress of technology, it is recommended to strengthen the improvement of the accuracy and stability of the ductility instrument to improve the reliability of the test.