Bentonite’s expansion index

Equipment:

1. Plug-scale measuring cylinder: 100ml, from the bottom of the inner side to the 100ml scale value, the height is 180mm±5mm.
2. Thermometer: range 0℃±0.5℃～105℃±0.5℃
3. Balance: The accuracy is 0.01g

Bentonite test procedure:

Accurately weigh 2g±0.01g of bentonite sample that has been dried at 105℃±3℃ for 2h, and add the sample to a 100ml graduated cylinder containing 90ml of distilled water in multiple times. Each addition does not exceed 0.1g, and it takes about 30s. Add it slowly over time. After the previously added bentonite settles to the bottom of the measuring cylinder, add it again. The time interval between two adjacent additions is not less than 10 minutes until the sample is completely added to the measuring cylinder.

After all the additions are completed, carefully rinse the powder particles adhering to the inside of the graduated cylinder with distilled water to make them fall into the water, and finally increase the water level in the graduated cylinder to the 100ml mark, and cover it tightly with a glass stopper (after 2h, if you find the bottom of the graduated cylinder If there is a separation layer of air or water in the sediment, the graduated cylinder should be tilted at a 45 degree angle and slowly rotated until the sediment is uniform). After standing for 24 hours, record the graduated cylinder scale value of the sediment interface (the sediment does not include low density Peptized or flocculent substances), accurate to 0.5ml.

Record the temperature of the test chamber at the beginning and end of the test to the nearest 0.5°C.

Allowable tolerance

For two parallel measurements of the same sample, when the average value is greater than 10, the absolute error shall not be greater than 2ml, and when the average value is less than or equal to 10, the absolute error shall not be greater than 1ml.