1. What is Specific Gravity?

Specific Gravity (SG) is a dimensionless unit defined as the ratio of the density of a substance to the density of a reference substance (typically water for liquids and solids). For soils, it helps characterize the material properties and is used in various geotechnical calculations.

2. How Does the Calculator Work?

The calculator uses the specific gravity formula:

Where:

• \( Density_{soil} \) — Mass density of the soil sample (g/cm³)
• \( Density_{water} \) — Mass density of water (typically 1 g/cm³ at 4°C)

Explanation: The specific gravity indicates how much denser the soil is compared to water. Typical values for soils range from 2.60 to 2.80.

3. Importance of Specific Gravity

Details: Specific gravity is used in soil mechanics for void ratio calculations, moisture content determinations, and in the phase relationships of soils. It's essential for classification and understanding soil behavior.

4. Using the Calculator

Tips: Enter the measured density of your soil sample in g/cm³. The water density defaults to 1.0 g/cm³ (standard value at 4°C) but can be adjusted for different temperatures if needed.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical specific gravity for soils?
A: Most common minerals in soils have specific gravities between 2.60-2.80. Organic soils may have lower values (1.0-2.0).

Q2: Why is water density important in this calculation?
A: Since specific gravity is a ratio, the reference substance's density affects the result. Water density changes slightly with temperature.

Q3: How is soil density measured?
A: Typically using a pycnometer for small samples or sand replacement methods for field measurements.

Q4: Does specific gravity vary with soil moisture?
A: No, specific gravity is a property of the soil solids. However, bulk density (which includes voids) changes with moisture.

Q5: What are the units of specific gravity?
A: Specific gravity is dimensionless since it's a ratio of two densities with the same units.