This paper introduces the detailed steps and requirements of the asphalt standard viscometer method, which is suitable for determining the viscosity of liquid petroleum asphalt, coal asphalt and emulsified asphalt. By adjusting the test temperature and pore size, the viscosity value of the asphalt in the flow state can be accurately measured. The article describes in detail the composition of the instrument, sample preparation, test procedures and result reports to ensure the accuracy and repeatability of the measurement results.
The purpose and scope of the test
This method is suitable for determining the viscosity of asphalt materials at different temperatures using a standard viscometer. The determination of viscosity can characterize the fluidity of materials and help determine their performance in practical engineering applications. Especially in pavement construction, the control of viscosity directly affects the construction quality and pavement service life. This method is suitable for petroleum asphalt, coal asphalt and emulsified asphalt and other materials. The test results should indicate the measurement temperature and the pore size of the flow pore, and be expressed by C [l is the test temperature (°C), d is the pore size (mm)].
Instrument and material requirements
Road Asphalt Standard Viscometer – This equipment consists of a sink, a sample tube, a ball plug, a thermometer and an acceptance bottle, etc. The inner diameter of the sink is 160mm, the depth is 100mm, and it is equipped with a water circulation system to keep the temperature of the liquid in the sink constant, and the temperature accuracy is ±0.2°C.
Sample Tube - used to load the asphalt sample to be tested, the bottom is equipped with flow holes with different pore sizes, the pore diameter is 3mm, 4mm, 5mm and 10mm optional, according to the characteristics of the sample to select the appropriate pore size.
Ball plug – used to plug the flow hole of the sample tube, the diameter and length of the ball plug vary according to the pore size, and is used to determine the height of the sample level.
Thermometer – with an accuracy of 0.1°C, it is used to measure the temperature in the specimen and the Water Tank.
Acceptance Bottle – used to collect outgoing specimens with a capacity of 100 mL and graduation markings of 25 mL, 50 mL, 75 mL and 100 mL for easy reading.
Thermostatic Water Tank - used to control the test temperature, the temperature control accuracy is ±0.1°C.
Test procedure
Depending on the type and consistency of the material, select the appropriate pore size of the sample tube and place it in the tank. Plug the flow hole with a ball plug to prevent the specimen from flowing out in advance. The temperature of the Thermostatic Water Bath is adjusted to the test temperature, and the Water Tank is connected to the viscometer to ensure the normal water circulation.
The asphalt specimen is heated to 2-3°C above the test temperature (or cooled to 2-3°C lower) than the test temperature and injected into the sample tube, and the liquid level reaches the ball plug rod mark. The sample tube is then placed in the Water Tank and kept at a constant temperature for 30 minutes to ensure that the sample temperature meets the requirements.
Lift the ball plug so that the specimen flows into the receiving bottle. The timing starts when the sample flows into 25mL and stops when it flows to 75mL. The time taken to record the outflow of the sample for 50mL is the viscosity of the sample, accurate to the second.
Each specimen is measured at least twice in parallel, and the average value is taken as the final result. When the difference between the two measurements is not greater than 4% of the mean value, the test result is valid.
Precautions
1. In order to ensure the accuracy of the test, the temperature of the sample should be strictly controlled during the test, and the temperature error of the constant temperature tank should not exceed ±0.1°C.
2. After the sample is injected into the sample tube, it should be stirred in time to ensure that the temperature of the sample is uniform.
3. After each test, the equipment should be thoroughly cleaned, especially the sample tube and flow hole, to avoid the influence of residual samples on the results of the next test.
4. The selection of flow pore size should be reasonably determined according to the viscosity of the sample, and the larger pore size should be selected for thicker asphalt materials.
Data analysis and reporting
The report of the test data shall indicate the measurement temperature and pore size specifications. The allowable error for repeat trials is 4% of the mean. The test results are expressed as viscosity values, and the final result should be an integer.
conclusion
Based on the T 0621-1993 standard asphalt viscosity test method, it provides an accurate and reliable method for viscosity determination. Through the measurement of the flow state of the specimen, the rheological properties of asphalt materials can be evaluated, so as to provide a scientific basis for the selection of asphalt in road engineering.
summary
The standard viscosity test for asphalt (standard viscometer method for road asphalt) provides an accurate and reliable way to determine the viscosity of liquid asphalt to evaluate its performance in real-world engineering applications. This method ensures accurate measurement of bitumen in the flow state by adjusting the test temperature and flow pore size. The detailed test procedures and instrument requirements make the method have high repeatability and reliability, and can provide a scientific basis for road construction, so as to improve the construction quality and prolong the service life of the pavement.
