Asphalt dynamic viscosity meter (vacuum depressurization capillary method)

SYD-0620 typeAsphalt dynamic viscosity meter (vacuum depressurization capillary method)

This method is applicable for determining the dynamic viscosity of viscous petroleum asphalt using a vacuum depressurization capillary viscometer. Unless otherwise specified, the test temperature is 60 ℃ and the vacuum degree is 40kPa.

[Instruments and Materials]

1. Vacuum pressure reducing capillary viscometer: a set of 3 capillary tubes, the shape of which is shown in Figure 1, and the model and size are shown in Table 1.

2 thermometers: 50 ℃~100 ℃, with a division of 0.1 ℃

3 Constant temperature water bath: made of hard glass, its height should be such that when the viscometer is placed, the highest time mark should be at least 20mm below the liquid level. It is equipped with a heating and temperature automatic controller, which can keep the water temperature at the test temperature of 0.1 ℃, and has a stirrer and clamping device. The temperature difference at different positions in the sink shall not exceed 0.1 ℃. The temperature control precision of the insulation device should reach 0.1 ℃.

4. Vacuum pressure reduction system: The vacuum degree reaches a pressure of 40kPammHg ± 66.5Pa (300mmHg ± 0.5mmHg), and the schematic diagram of the entire device is shown in Figure 2. There should be no air leakage at each connection to ensure airtightness. When opening the capillary pressure reducing valve for measurement, there should be no negative pressure reduction. Connect a vacuum pump at the open end to evacuate.

5 stopwatches: 2, with a division of 0.1s, and a total range error of no more than ± 0.05% within 15 minutes.

[Method and Steps]

preparation

Estimate the viscosity of the sample and select the model of vacuum capillary viscometer based on the time it takes for the sample to flow through the specified volume for at least 60 seconds.

Wash the vacuum capillary viscometer thoroughly with solvents such as trichloroethylene. If the viscometer has oil stains, it can be carefully washed with detergent, distilled water, etc. After washing, dry in an oven or blow dry with hot air through cotton.

Prepare asphalt samples according to T0602 of this regulation, and carefully heat the dehydrated and sieved samples to a fully flowing state. During heating, stir appropriately to ensure even heating. Then pour the sample into another small container that is convenient for filling into the capillary tube, with a quantity of 50ml each, and cover it with a lid.

Heat the sink and adjust the temperature to within the range of 60 ℃± 0.1 ℃. The thermometer should be pre calibrated.

Heat the selected vacuum capillary viscometer and sample in an oven (135 ℃± 5 ℃) for 30 minutes.

4 Experimental Steps

Place the heated viscometer in a container, and then inject the hot asphalt sample from tube A into the capillary viscometer

The sample should not stick to the pipe wall and the liquid level of the sample should be within ± 2mm of the E-line. Place the capillary viscometer with the loaded sample back into the oven (135 ℃± 5.5 ℃) and keep it warm for 10 minutes ± 2 minutes to allow the bubbles generated by the sample in the tube to escape.

Take out 3 capillary viscometers from the oven, cool them at room temperature for 2 minutes, and install them in a constant temperature water bath that maintains the test temperature. The position should be such that the I-line is at least 20mm below the liquid level in the bath. The operation time from taking out the viscometer from the oven to placing it in the constant temperature water bath should be controlled within 5mm.

Connect the vacuum system to the viscometer, start the vacuum pump or vacuum pump to achieve a vacuum degree of 40kPa (300mmHg ± 0.5Hg).

After keeping the viscometer in a constant temperature water bath for 30 minutes, open the valve connecting the pressure reducing system. When the sample reaches the * mark, start two stopwatches at the same time to measure the interval time between consecutive pairs of marks, accurate to 0.1 seconds. Record the symbol and interval time of * marks that exceed 60 seconds.

Perform parallel tests on the other two viscometers using this method.

After the experiment is completed, remove the capillary tube from the constant temperature water bath and clean it in the following order:

Invert the capillary tube in a beaker of appropriate size and place it in an oven preheated to 135 ℃ for about 0.5 to 1 hour to allow the asphalt in the capillary tube to flow out completely, but the time should not be too long to prevent the asphalt from coking and adhering to the tube.

Take out the beaker and capillary tube from the oven, quickly and gently wipe the asphalt around the capillary tube mouth with clean cotton yarn.

Inject trichloroethylene solvent from the sample tube mouth, and then use an ear ball to aim at the upper opening of the capillary tube to extract air. The asphalt gradually dissolves and is sucked out from the capillary tube mouth, entering the ear ball, and repeated several times. Until the injected trichloroethylene is clear and transparent after extraction, rinse with distilled water, dry, and store for future use.

【 Usage and Precautions 】

1. This tester should be placed horizontally on a workbench, with a room temperature of 0-30 ℃, a relative humidity of no more than 80%, no vibration, no corrosive gases, and good grounding protection.

2. Before use, inject pure tap water into a constant temperature water bath with a water level of about 15mm above the upper plane, and connect the two instruments together using a random hose.

3. Plug both instruments into the power supply (220V, 50Hz), first turn on the power switch of the constant temperature water bath section, adjust the temperature to the desired value according to the instructions of the temperature controller, start the heating and stirring switch, and after a period of time, the desired temperature value can be reached.

4. After setting up the constant temperature water bath section, turn on the power switch of the vacuum control section. When the power switch is turned on, the vacuum pump starts working directly, and the user can set the vacuum degree according to the vacuum gauge manual (generally, it has already been set for the user at the factory and does not need to be reset). According to the values on the table, slowly adjust the vacuum degree with the pressure regulating valve, and this process needs to be repeated several times. At this point, the valve connecting the capillary tube must be closed.

6. During the experiment, turn on the lighting switch to clearly observe the entire experiment process