ASTM D4 Standard Test Method for Bitumen Content
8. Procedure No. 2
8.1 Weigh approximately 2 g of the sample into a tared 50-mL beaker. Add to the beaker about 0.5 g, weighed to the nearest 0.001 g, of freshly dried CAFA. Cover with about 25 mL of carbon disulfide and stir the filter aid into the liquid. Let stand, covered with a watch glass, at least 1 h, stirring occasionally in order to dissolve the sample completely.
8.2 Transfer 0.45 to 0.55 g of dry CAFA to a clean, dry, filtering crucible. Distribute the Celite evenly over the bottom. Immediately weigh and record the mass of crucible plus Celite.
8.3 Immediately before starting the filtering process, stir the filter aid into the liquid. Wet the CAFA mat in the crucible with carbon disulfide. Pour the solution from the beaker onto the pad, filling the crucible to the top. Apply light suction and, as the liquid filters through, pour the remaining contents of the 50-mL beaker into the crucible. Wash the beaker with a small amount of carbon disulfide and transfer all sediment from the beaker to the mat. Do not allow the CAFA mat to dry out until filtration is complete. Wash with carbon disulfide until the filtrate is substantially colorless, then apply strong suction to remove the remaining carbon disulfide. Remove the crucible from the adapter, wash the bottom free of any bitumen, and place on top of the oven until practically all of the carbon disulfide has been driven off. Place in the oven at 110 more or less 10°C for at least 20 min. Cool in a desiccator and weigh.
8.4 If insoluble matter adheres to the beaker, dry the beaker in the oven at 110°C and weigh. Add the mass of this adherent material as a correction to the mass of the insoluble matter in the crucible.
8.5 Ignite the evaporating dish to a dull red heat, cool in a desiccator, and weigh. Pour the filtrate from the filtering flask into the dish and wash the flask thoroughly with carbon disulfide, putting these washings into the dish also. Burn off the carbon disulfide in a hood and ignite the residue until no black or glowing spots remain. Extreme care must be exercised during the ignition to prevent the light mineral matter from being blown out of the dish. Cool in a desiccator and weigh immediately. This mass shall be added as a correction to the weight of the insoluble matter in the crucible.
8.6 If a determination of mineral matter is required, heat the crucible and its contents from 8.3 until they glow with a dull red color. Hold at this temperature until all carbon has been consumed; then raise the temperature to produce a bright red. After cooling, add to the residue about five times its mass of saturated ammonium carbonate solution and let it digest for 1 h at room temperature in a covered beaker; then dry in an oven at 105 to 110°C to constant mass (Note 2). Add the corrections described in 8.4 and 8.5 to the mass of mineral matter in the crucible.
8.7 The mass of additional filter aid used must be subtracted from the total mass of insoluble residue and also from the total mass of mineral matter in the crucible in order to obtain net mass.
