This standard details the laboratory methods for determining the specific gravity of tar and bitumen using a specific gravity bottle, pycnometer, or displacement balance. Determining the specific gravity is crucial for volumetric calculations in asphalt mix design and converting measured mass into volume for quality control.
Describes the method for determining the specific gravity of tar and bitumen, crucial for quality control of waterproofing materials.
Quick Reference Values
Standard test temperature27°C
Temperature tolerance for water bath± 0.1°C
Specific gravity bottle capacity50 ml
Key Formulas
Specific Gravity = (W3 - W1) / ((W2 - W1) - (W4 - W3)) — where W1=weight of empty bottle, W2=weight of bottle filled with water, W3=weight of bottle partially filled with bitumen, W4=weight of bottle + bitumen + filled with water
Practical Notes
Ensure all entrapped air is completely eliminated from the bitumen sample before final weighing (often done by gentle warming), as air bubbles will falsely lower the specific gravity result.
Strict adherence to the 27°C water bath temperature is critical because bitumen density is highly temperature-sensitive.
The specific gravity bottle method is typically used for liquid or less viscous semi-solid bitumens, while the pycnometer is better suited for harder semi-solid or solid materials.