What is the Difference Between Coal Tar and Asphalt?

Coal tar and asphalt are both dark-colored, hydrocarbon-rich substances used in construction applications, but they have different origins, properties, and uses. The key difference between coal tar and asphalt is:

• Origin: Coal tar is derived from the destructive distillation of organic substances such as coal, wood, or other bituminous materials, while asphalt is obtained as a residue from the distillation of petroleum or from natural deposits.
• Composition: Coal tar consists of high carbon content and contains polycyclic aromatic hydrocarbons (PAHs), heterocyclic compounds, and phenols. Asphalt, on the other hand, is a composite material composed of mineral aggregates and bitumen, with varying degrees of hardening at different conditions.
• Water Resistance: Coal tar is more resistant to water, gas, oil, and other chemicals due to its chemical makeup. Asphalt is less resistant to these substances.
• Odor and Contractor Experience: Asphalt is less odorous and causes far less burning to the contractor compared to coal tar.
• Usage: Coal tar is known for its hard, durable film, deep dark color, and increased fuel resistance. It is also used in the medical field due to its antifungal, anti-inflammatory, anti-itch, and antiparasitic properties. Asphalt is more flexible, faster drying, and has no skin irritation or strong smell. It is also more forgiving in cooler temperatures. However, asphalt requires additives to match the durability and fuel resistance of coal tar.

In summary, coal tar and asphalt are both important hydrocarbon materials with different origins, properties, and uses. Coal tar is more resistant to water, gas, oil, and other chemicals, while asphalt is less odorous and more flexible.

Comparative Table: Coal Tar vs Asphalt

The key difference between coal tar and asphalt is their origin and composition. Coal tar is a dark-colored substance that forms as a byproduct of the production of coke from coal, while asphalt is obtained as a residue from the distillation of petroleum or from natural deposits. Here is a table summarizing the differences between coal tar and asphalt:

Both coal tar and asphalt are hydrocarbon substances and are collectively known as bituminous materials. They have different properties and applications, with coal tar being more commonly used in medical and wood preservation applications, while asphalt is more widely used in construction and paving applications.