1. What is Bulk Specific Gravity of Asphalt?

Definition: Bulk specific gravity (SG_bulk) is the ratio of the mass of asphalt mix to the mass of an equal volume of water at a specified temperature.

Purpose: It's a critical parameter in asphalt mix design, used to calculate air voids, voids in mineral aggregate, and other important mix properties.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( SG_{bulk} \) — Bulk specific gravity (unitless)
• \( m \) — Mass of asphalt mix (kg)
• \( V_{total} \) — Total volume of asphalt mix (m³)
• \( \rho_{water} \) — Density of water (typically 1000 kg/m³)

Typical Values: For asphalt mixes, bulk specific gravity typically ranges between 2.3 and 2.5.

3. Importance of Bulk Specific Gravity

Details: Accurate measurement of bulk specific gravity is essential for quality control in asphalt production, ensuring proper compaction and durability of the pavement.

4. Using the Calculator

Tips: Enter the mass of asphalt in kg, total volume in m³, and water density (default 1000 kg/m³). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between bulk and apparent specific gravity?
A: Bulk SG includes air voids in the calculation, while apparent SG considers only the volume of impermeable material.

Q2: How is total volume typically measured?
A: In lab testing, volume is often measured using the saturated surface dry (SSD) method or paraffin-coated method.

Q3: Why is water density important in this calculation?
A: Specific gravity is defined relative to water, so we need water's density as the reference point.

Q4: What affects bulk specific gravity values?
A: Factors include aggregate type, asphalt content, compaction level, and air void content.

Q5: How does this relate to field compaction?
A: Field cores are tested for bulk SG to verify they meet the design target (usually 92-96% of theoretical maximum SG).