My first soil mechanics lab was an exercise in analyzing the moisture content of a soil mixture. Soil is an aggregate consisting of what are called “phases”. The 3 phases are solids (tiny rocks and minerals), water, and air. The water and air make up what is called the void space. In evaluating moisture content (w), we are only interested in the water and solids portion. In fact, the moisture content is defined as the ratio of the weight of the water content (Ww) to the weight of the solid content (Ws). The weight of the air is considered negligible.
The procedure we followed to obtain values for these calculations was to use 3 small metal tins or canisters. First we used a digital scale to measure the weight of each canister. This weight we called W1. Next we partially filled each canister with a small sample of soil. Next we measured the canister and the soil. This weight we called W2. Finally we placed the canisters in a soil drying oven to dry out the soil and remove the water from the samples. After 24 hours we returned to the lab and used the digital scale to measure the dried soil samples in the canisters. This weight we called W3. To find the weight of the water (Ww) we used:
To find the weight of the solids (Ws) we used:
Here is a tabulation of the results we obtained: