AASHTO T 330:07(2019) Standard Method of Test for The Qualitative Detection of Harmful Clays of the Smectite Group in Aggregates Using Methylene Blue.
Amber-colored buret of at least 50-mL capacity with 0.1-mL graduations.
5.2. Magnetic mixer with stir bar.
5.3. Balance complying with M 231, Class G 1.
5.4. Glass rod of approximately 250-mm (10-in.) length and approximately 8-mm (0.3-in.) diameter.
5.5. Timer or stopwatch.
5.6. Pan and 75-um (No. 200) sieve.
5.7. Volumetric flask of 1000-mL capacity.
5.8. Whatman No. 2 filter paper.
5.9. Three 500-mL griffin beakers.
5.10. Methylene Blue, reagent grade-dated and stored for no more than four months in a brown bottle wrapped with foil in a dark cabinet at lab temperature.
Note 2 —One gram of Methylene Blue is dissolved in enough distilled water to produce 200 rnL of solution, with each 1 mL of solution containing 5 mg of Methylenc Blue.
5.11. Distilled water at lab temperature.
5.12. Oven capable of maintaining a temperature of 110 ± 5°C (230 ± 9°F).
Note 3—For the purposes of this procedure. lab temperature is defined as 15 to 25°C (60 to 77°F).
This test shall be performed on a sample of material passing the 75-jim (No. 200) sieve, taken from the washed portion of a representative sample of individual or combined material (as required). The material shall be washed through the 75-um (No. 200) sieve and collected in a clean container. This container shall be large enough to hold several gallons of water and material passing the 75-um (No. 200) sieve. Allow the material to settle and remove the excess water. The portion passing the 75-um (No. 200) sieve is collected, transferred to a smaller container, and dried for testing. The collected material is mixed thoroughly prior to testing. The minimum oven- dry mass of the collected material shall be at least 30 g to ensure enough material for a possible retest.
7.2. Add 30 mL of distilled water and stir with the mixer to make a slurry.
7.3. With the slurry still mixing, fill the buret with the Methylene Blue solution, add 0.5 mL of the solution to the slurry, and stir for 1 mm.
7.4. Remove a drop of the slurry, using the glass stirring rod, and place on the filter paper.
7.5. Observe the appearance of the drop on the filter paper. The end point is indicated by the formation of a light blue halo around the drop. Continue adding the Methylene Blue solution to the slurry in O.5-mL increments stirring for I mm after each addition, then testing, until the end point is reached.
7.6. After the end point is reached, continue stirring for 5 mm and retest.
Note 4 With experience, the person performing the test can reach the end point more quickly by skipping early increments.AASHTO T 330 pdf download.