1. What is Porosity from Bulk Density?

Definition: This calculator determines the porosity (void fraction) of a material based on its bulk density and particle density.

Purpose: It helps geologists, soil scientists, and material engineers quantify the pore space in granular materials or porous media.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \phi \) — Porosity (unitless, between 0 and 1)
• \( \rho_{bulk} \) — Bulk density (kg/m³)
• \( \rho_{particle} \) — Particle density (kg/m³)

Explanation: The ratio of bulk to particle density gives the solid fraction, and subtracting from 1 gives the void fraction (porosity).

3. Importance of Porosity Calculation

Details: Porosity affects fluid flow, storage capacity, strength, and thermal properties of materials. It's crucial in geology, construction, and material science.

4. Using the Calculator

Tips: Enter bulk density (mass of dry material divided by total volume including pores) and particle density (default 2650 kg/m³ for quartz). Bulk density must be less than particle density.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical particle density for soils?
A: For mineral soils, particle density is typically 2.65 g/cm³ (2650 kg/m³) which is quartz density. Organic matter lowers this value.

Q2: How do I measure bulk density?
A: Measure dry mass of a known volume of material (including pores). Core sampling is common for soils.

Q3: What porosity values are typical?
A: Well-packed sands: 0.3-0.4, clays: 0.4-0.6, gravels: 0.2-0.4, concrete: 0.1-0.2.

Q4: Why can't bulk density exceed particle density?
A: Particle density is the maximum possible (no pores). Bulk density must be lower as it includes pore space.

Q5: How does porosity relate to permeability?
A: Higher porosity often means higher permeability, but pore connectivity and size matter more than total porosity.