Geotechnical Engineering

Step 1: State the purpose of the oven drying method. The goal is to remove the water from the soil pores by evaporation without altering the soil's chemical composition, particularly by not burning the organic matter present.
Step 2: Identify the standard temperature range. The standard temperature for drying soil samples is maintained between 105 C and 110 C. This range is chosen because it is safely above the boiling point of water (100 C), ensuring efficient evaporation, but below the temperature at which soil organic matter begins to char or decompose, which would lead to an inaccurate measurement of the dry soil mass.

Step 1: State the formula for moisture content (dry weight basis).
The moisture content ( ) is the ratio of the mass of water ( ) to the mass of dry soil solids ( ), expressed as a percentage. Step 2: Calculate the mass of water and mass of solids from the given data.
- Mass of moist soil (total mass), g
- Mass of oven-dried soil (mass of solids), g
- Mass of water, g
Step 3: Calculate the moisture content.

Step 1: Define void ratio ( ) and porosity ( ).
Let be the volume of voids, be the volume of solids, and be the total volume of the soil sample.
- Void Ratio ( ): The ratio of the volume of voids to the volume of solids. - Porosity ( ): The ratio of the volume of voids to the total volume. Step 2: Establish a relationship between them.
We know that the total volume is the sum of the volume of voids and the volume of solids: .
Let's express in terms of . Start with the definition of porosity: Divide the numerator and the denominator by : Substitute : This is a fundamental relationship.
Step 3: Check which of the given options matches this relationship. Let's analyze option (C): . Move the term to the left side: Factor out : Solve for : This matches the derived relationship. Therefore, option (C) is the correct representation.

Step 1: Recall the standard procedure for determining soil moisture content. The oven-drying method is the most common and accurate method for determining the moisture content of a soil sample. This method involves weighing a moist soil sample, drying it in an oven at a specific temperature until it reaches a constant weight, and then weighing it again.
Step 2: Identify the standard drying period. To ensure all the soil water has evaporated, the sample is typically kept in the oven for a period of 24 hours. The temperature is maintained at 105 C to 110 C. After 24 hours, the sample is weighed, and it may be returned to the oven for shorter periods and re-weighed until consecutive weighings show no change, confirming all moisture has been removed. The 24-hour period is the standard initial duration.