For soil having a void ratio of 0.75 and a percentage saturation of 85%, determine porosity and air void ratio
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STUDENT
To determine the porosity and air void ratio of a soil given its void ratio and percentage saturation, you need to understand the relationships between these parameters.
1. Porosity: Porosity is a measure of the volume of voids (i.e., the empty spaces) in a soil sample relative to its total volume. It is expressed as a decimal or percentage.
The formula to calculate porosity is:
Porosity = (Void Ratio / (1 + Void Ratio)) * 100
In this case, the given void ratio is 0.75. Plugging this value into the formula, we get:
Porosity = (0.75 / (1 + 0.75)) * 100
Calculating this, Porosity ≈ 42.86%
So, the porosity of the given soil is approximately 42.86%.
2. Air Void Ratio: Air void ratio is the ratio of the volume of air voids to the volume of solid particles in a soil sample. It is expressed as a fraction, decimal, or percentage.
The formula to calculate air void ratio is:
Air Void Ratio = (1 - Saturation) / (1 + Void Ratio - Saturation)
In this case, the given saturation is 85% (or 0.85). Plugging this value and the void ratio (0.75) into the formula, we get:
Air Void Ratio = (1 - 0.85) / (1 + 0.75 - 0.85)
Calculating this, Air Void Ratio ≈ 0.6
So, the air void ratio of the given soil is approximately 0.6 (or 60%).
Note: These calculations assume that the soil contains only air and water. In reality, soils can have other constituents such as organic matter, minerals, or contaminants that may affect the calculations.