Determining the Mass of Water Contained in a Rock Sample

Determining the Mass of Water Contained in a Rock Sample

Objective

To find out how much water is contained in a rock sample by measuring the mass difference before and after drying.

Standards used

IS 13030:1991 

Apparatus Used

1. Electric Oven

Electric oven

• Temperature: 105 ± 3°C and capable for maintaining it for 24 Hours.
• Accuracy: ± 1°C

2. Balance

Weighing balance 

• Capacity: Suitable for the sample size
• Accuracy: 0.01% of the sample weight

3. Desiccator 

Procedure

1. Prepare the Container:

Moisture container 

• Clean and dry the container and its lid.
• Weigh the empty container with its lid and record this weight as M1

2. Weigh the Sample:

• Place the rock sample in the container.
• Weigh the container with the sample and record this weight as M2.

3. Dry the Sample:

• Remove the lid from the container.
• Place the container with the sample in the oven set at 105 ± 3°C.
• Allow the sample to dry until it reaches a constant weight.

4. Cool and Weigh the Dried Sample:

• After drying, remove the container from the oven.
• Replace the lid and let the container cool in a desiccator for 30 minutes.
• Weigh the container with the dried sample and lid and record this weight as M3.

Calculation

Calculate the water content using the formula:

Water Content (w)=(M2−M3/M3−M1) ×100

Where:

M1 = Mass of the container and lid (in grams)
M2 = Mass of the container, lid, and wet sample (in grams)
M3 = Mass of the container, lid, and dried sample (in grams)

Report

Report the water content to the nearest 0.1%.

References: IS 13030:1991, ISRM