This method is intended to determine the percent residue of emulsified asphalt. The apparatus and procedure are identical to Iowa Test Method No. 615, Residue by Evaporation Procedure.
a) Electric Heater Container-the container in which the sample is to be tested shall be an iron, hemispherical, sand bath dish, 6 in. (150 mm) in diameter.
b) Oven Container-the container in which the sample is to be tested shall be, a disposable aluminum pan 3”x5”x2”.
2. Heat Source-
a) Continuous adjusting electric heater
b) Convection oven set at temperature range of 235°F to 275°F (113°C to 135°C)
3. Balance-capable of weighing accurately to within 0.5 gram
B. Test Procedure
I. Electric Heater Procedure
1. Weigh 100 ± 5 grams of thoroughly mixed emulsified asphalt to the nearest 0.5 gram into the sand bath dish.
2. Place the dish containing the sample on the electric heater and adjust to moderate heat so that the sample boils, without popping and spitting.
3. Continue the boiling until the bubbling slows at which time the heater is adjusted to very low heat.
4. When the bubbling stops, immediately remove the dish from the heater and weigh to the nearest 0.5 gram.
II. Convection Oven Procedure
1. Weigh 100 ± 5 grams of thoroughly mixed emulsified asphalt to the nearest 0.5 gram into the aluminum pan.
2. Place the pan containing the sample in the oven. The sample will begin to bubble.
3. After approximately 90 to 120 minutes the amount of bubbles will diminish and the material will take on a smooth black finish. Confirm completion by verifying sample has reached a constant mass to the nearest 0.5 gram.
C. Calculation & Report
Calculate the percent of residue as follows:
Where: A = the sample weight (mass) in grams
B = weight (mass) of the dish and residue in grams
C = tare of dish in grams
Report the result of one test to the nearest 0.1 percent.
NOTE 1: When specifications require that tests be performed on the emulsion residue, the test samples shall be prepared immediately after step B4, while the residue is hot and in a fluid condition. If the amount of residual asphalt is insufficient for testing, the emulsion sample size for this method may be increased accordingly.
NOTE 2: Rejection of an emulsion, except diluted emulsions, cannot be made on the percent residue, or results of tests on the residue, when determined by this method. The noncompliant emulsions must have the residue obtained by distillation. Percent residues by this method on diluted emulsions are valid.
Electric Heater & Sand Bath Dish