Applied Clay Mineralogy Phần 10 pdf

3b. Sample preparation

3b.1. Approximately 700 g of sample is weighed in a 1000 ml beaker.

3b.2. Mix sample for approximately 1 min.

3b.3. Transfer sample to beaker and measure the Brookfield viscosity.

3b.4. Record reading.

3b.5. Return sample to 1000 ml beaker.

3b.6. Add two drops of deflocculant.

3b.7. Repeat steps 2–6 until minimum viscosity is reached.

3c. Procedure

3c.1. Measure out 200 ml of sample.

3c.2. Filter 200 ml of sample through a baroid filter press using Whatman #42

filter paper with a pressure of 90 psi (filter slurries for 1 h).

3c.3. After filtration period, remove baroid and allow sample to drain for

5 min.

3c.4. Remove cast from baroid and record weight. This is the casting rate.

3c.5. Place cast into drier for a minimum of 18 h.

3c.6. Remove cast from drier and place in dessicator until it reaches room

temperature.

3c.7. Record weight of cast.

3d. Calculations

Casting rate: Read directly from scale

% moisture retention ¼ wet weight of cast dry weight of cast

dry weight of cast 100

4. Modulus of rupture (MOR)

Purpose: To determine the dry strength of a clay.

4a. Apparatus

Plaster mold which forms bars 3/4 in. 7 in.

Low shear mixer

Drying oven

Dessicator

Compression tester

Calipers

4b. Sample preparation

4b.1. Clay and slurry.

4b.1a. Clay and water are mixed together to form a slurry with a specific gravity

of 1.519 (55.52% solids).

4b.1b. Water is added to a slurry so that a specific gravity of 1.519 is achieved.

4b.2. Mix in the weight of quartz which will give a 50% clay and 50% flint body.

4c. Procedure

4c.1. Add deflocculant to sample until minimum Brookfield viscosity is reached.

4c.2. Cast samples in plaster molds forming bars 3/4 in. diameter and 7 in. long.

Allow bars to cast overnight.

4c.3. Remove bars from mold and allow to air dry for 6 h.

4c.4. Place bars in drier at 2401F overnight.

4c.5. Place bars in dessicator and allow to cool to room temperature.

4c.6. Remove bars one at a time from dessicator and break on a compression

tester with a span of 2 in.

4c.7. Record breakage pressure in pounds and accurately measure the diameter of

the bar at the breaking point in inches with calipers.

Appendix B 163