Centrifugal separation is an effective method for determining the content of asphalt mixture, which is suitable for many types of asphalt mixture. This method accurately determines the amount of bitumen in the mixture by placing the sample in a centrifuge and using centrifugal force to separate the asphalt and the mineral material. The protocol includes sample preparation, centrifugation, extraction, and sieving to ensure the accuracy and reliability of the final results.
Test of asphalt content in asphalt mixture (centrifugal separation method)
Purpose and Scope of Application
This method adopts centrifugal separation method, which is mainly used to determine the asphalt content or oil-stone ratio in the asphalt mixture mixed with viscous petroleum asphalt. It is suitable for testing the amount of asphalt during the construction of hot-mix hot-paved asphalt mixture pavement to evaluate the product quality of the mixing plant. In addition, this method can also be used to detect the amount of asphalt in asphalt mixture during old road survey, and to evaluate the aging properties of asphalt through the extracted asphalt solution.
Technical requirements for instruments and materials
Centrifugal extractor – including specimen container and centrifugal separator with a speed of not less than 3000 r/min. The equipment needs to be equipped with a filtrate outlet and an oil-resistant annular filter paper seal.
Recovery bottles – with a capacity of at least 1700 mL.
Pressure filtration device
Balance – inductance not more than 0.01 g.
Graduated cylinder – 1 mL indexing value.
Electric oven – equipped with automatic temperature regulator.
Trichloroethylene – for industrial use.
Ammonium carbonate saturated solution – used to determine the mineral powder content in filter paper by combustion method.
Others – small spatula, metal plates, large beakers, etc.
Methods and Steps:
Preparation
1. According to the "Asphalt Mixture Sampling Method", collect the asphalt mixture sample from the mixing plant truck, put it into a metal tray and mix, wait for the temperature to drop slightly below 100 °C, and the sampling amount is 1000~1500 g (the high limit for coarse-grained type and the low limit for fine-grained type).
2. The samples on the construction site should be dried with an electric fan and sampled after proper heating in the oven to avoid the crushing of aggregates caused by hammering.
Test procedure
Soaking and stirring - the sample is immersed in trichloroethylene solvent, soaked for 30 minutes and stirred to fully dissolve the asphalt.
Centrifugal separation - the mixture and solution are poured into the centrifugal separator, the clean annular filter paper is weighed, and the quality is recorded. Cap and turn on the centrifuge until the bitumen solution flows into the recovery bottle through the outlet.
Repeat the cleaning - if the outgoing extract is clear and yellowish, stop; Otherwise, repeat the addition of new solvent until conditions are met.
Drying & Weighing – Remove the filter paper and dry it in a 105°C oven, weigh the mass to calculate the weight gain of the finezing. After the aggregate is removed, it is also dried and weighed.
Mineral Powder Analysis – Filter the asphalt solution using a pressure filter and calculate the mineral powder content based on the weight gain. If a pressure filter is not available, the combustion method is used for the measurement.
Calculations & Reporting
At least two parallel trials, the average was taken as the result. If the difference between the two results is greater than 0.3% but less than 0.5%, the parallel test should be supplemented, and the average of the three tests should be used as the result, and the difference between the maximum and minimum values should not be greater than 0.5%.
Asphalt mixture gradation inspection method
Purpose and Scope of Application
This method is used to determine the mineral gradation of asphalt mixture in the process of asphalt pavement construction to ensure the evaluation of construction quality.
Technical requirements for instruments and materials
Standard screen - the size includes 53.0mm, 37.5mm, 31.5mm, etc., and the corresponding screen number is selected according to the asphalt mixture gradation.
Balance - inductance not more than 0.1 g.
Shake the sieve machine
Oven – equipped with automatic temperature controller.
Others – sample trays, brushes, etc.
Methods and Steps:
Preparation
1. Select representative samples from the mixing plant according to the "Asphalt Mixture Sampling Method".
2. The extracted mineral mixture is dried in a 105°C oven and cooled to room temperature.
3. According to the design requirements of ore gradation, select the required standard screen.
Test procedure
1. Weigh all mineral samples to an accuracy of 0.1 g.
2. Put the mineral mixture into the shaker for sieving for 10 minutes. After that, hand sieving is carried out one by one to ensure that the mass of the sieved particles does not exceed 0.1% of the total mass.
3. For the particles of 0.075mm sieve, the water sieve method can be used for determination, or appropriate conversion can be carried out according to the need.
summary
The determination of asphalt mixture content by centrifugal separation can provide important data support for road construction. This method not only improves the accuracy of the test, but also effectively evaluates the performance and quality of the asphalt. Accurate bitumen content data is essential to ensure the safety and durability of roads, so it is important in practical applications. Choosing the right inspection method can help improve the overall quality of the construction project.
