AS NZS 2891.7.1:2015 – Methods of sampling and testing asphalt Method 7.1: Determination of maximum density of asphalt-Water displacement method.
9.2 Pycnometer on balance method
The procedure shall be as follows:
(a) Place the test portion in the pycnorneter.
(b) Weigh the pycnometer, lid and test portion, and record the mass (rn3).
(c) Pour water into the pycnometer until the water level is about 50 mm above the level of the test portion. 2 mL of detergent solution may be added to the pycnometer to aid evacuation of air from the sample.
(d) Attach the pycnometer to the vacuum pump and evacuate the pycnometer to a vacuum of—90 kPa gauge pressure or lower, and maintain the vacuum for a period of not less than 1 5 minutes. Vigorously agitate the pycnometer frequently to loosen the particles and release any entrapped air.
NOTES:
1 Care should be taken when applying the vacuum particularly in the initial stages to prevent loss of material.
2 Care should he taken to ensure the sample is not left under vacuum for an excessive period of time as this may lead to rupture of’ the bitumen film and absorption of water by the aggregate; typically 15—20 minutes of vacuum with frequent agitation is sufficient.
3 Where a glass pycnomeler is used a rubber mat below the pycnometer is recommended.
(e) When no entrapped air is observed, release the vacuum slowly and disconnect the vacuum pump from the pycnometer.
(0 Fill the pycnorneter with water from the water bath and place in the water bath, ensuring no loss of the test portion during the process and that no air is introduced into the test portion.
(g) Leave the pycnorneter in the water bath until the water temperature in the flask and water bath are the same. Record the temperature of the water (t1).
(h) Top up the pycnometer with water from the water bath and slide on the lid, ensuring that no air bubbles are trapped.
(1) Remove the pycnometer from the water bath and with the lid securely held in place, invert the pycnometer several times.
(j) If’ air bubbles are observed, repeat Step (h) until all air is eliminated.
(k) Carefully dry the pycnometer. Weigh the pycnometer, lid, test portion and water, and record the mass (m4).
9.3 Flask under balance method
The procedure shall be as follows:
(a) Weigh the flask and record the mass (1115).
(b) Place the flask in the water bath allowing it to fill, ensuring no air bubbles are present.
(c) Suspend the fully immersed flask from the balance and record the mass in water (“). Record the temperature of the water (12).
(d) Remove the flask from the water bath, empty and dry.
NOTE: Step (a) to Step (d) determine the mass of the flask in water at the test temperature (12). Following an initial determination, only periodic checks need be carried out for each specific flask—at least six monthly.
(e) Place the test portion into the flask and record the mass of the test portion (m7). Pour water into the flask until the water level is about 50 mm above the level of the test portion. 2 mL of detergent solution may be added to the flask to aid evacuation of air from the sample.
(f) Seal the flask and connect it to the vacuum pump and evacuate the flask to a vacuum of —90 kPa gauge pressure or lower and maintain the vacuum for a period of not less than 15 minutes. Vigorously agitate the flask frequently to loosen the particles and release any entrapped air.
NOTES:
I Care should be taken when applying the vacuum particularly in the initial stages to prevent loss of material.
2 Care should be taken to ensure the sample is not left under vacuum for an excessive period of time as this may lead to rupture of the bitumen film and absorption of water by the aggregate. Typically 15—20 minutes of vacuum with frequent agitation is sufficient.
3 Where a glass flask is used a rubber mat below the flask during agitation is recommended.
(g) When no entrapped air is observed, release the vacuum slowly and disconnect the vacuum pump from the flask.
(h) Submerge the flask carefully into the water bath ensuring no loss of the test portion during the process and that no air is introduced into the test portion. Suspend the fully submerged flask from the balance.
(i) Record the mass of the test portion and flask in water (m8).
(j) Record the temperature of the water in the bath (12).
10 CALCULATIONS
10.1 On Balance method
The maximum density (max) for each test portion shall he calculated from the following equation.