Asphalt Vs Tar
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Asphalt Vs Tar: Which One Should You Use for Paving?
Ever wonder why asphalt roads dominate modern infrastructure while tar has faded into obscurity?
Choosing the right material for paving projects can be a daunting task. With terms like "asphalt" and "tar" often used interchangeably, it's crucial to understand the differences and make informed decisions.
In this comprehensive guide, we delve into the differences between asphalt and tar, helping you choose the best option for your paving needs.
By the end of this article, you'll understand the composition, appearance, application, durability, health and safety concerns, and environmental impacts of asphalt and tar, empowering you to make the right choice for your next project.
Understanding Asphalt and Tar: Primary Differences
Composition Differences
Asphalt is a composite material made of aggregates (like gravel, sand, or crushed rock) and bitumen, a viscous black substance derived from petroleum. It's the binding agent that holds everything together, providing durability and flexibility.
Tar, on the other hand, is a thick liquid produced by heating organic materials such as coal or wood. Historically, it served as a binder in road construction, known as "tarmacadam" or "tarmac." Unlike asphalt, tar's origin is not petroleum-based, and it owes its existence to the thermal breakdown of raw materials.
Appearance Differences
At first glance, both materials might look similar, but there are distinct differences:
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Color: Freshly laid asphalt boasts a deep, jet-black color that gradually fades to gray due to exposure to sunlight, rain, and traffic. Tar, especially coal tar, retains a darker, glossier appearance over time, maintaining its bold inky finish.
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Texture: Asphalt typically offers a smooth and even surface, ideal for roads and driveways. Tar, being a liquid, doesn't have a texture of its own but can create a slick surface. Historically, tarmac surfaces were coarser than modern asphalt.
Application Differences
Asphalt is the go-to material for a myriad of applications: roads, highways, parking lots, and even airport runways. Its ability to withstand heavy traffic and extreme temperatures makes it indispensable. Beyond paving, it's used in roofing, waterproofing, and stormwater management.
Tar's role in paving has diminished over time. Once popular in "tar and chip" driveways, it now serves niche uses. Most "tar and chip" surfaces today use liquid asphalt instead, offering a textured and budget-friendly alternative to asphalt.
Durability Differences
Asphalt's durability is unmatched. Its flexibility allows it to expand and contract with temperature changes, reducing the risk of cracking. It also resists chemical damage better than tar, standing up to substances like gasoline. With proper maintenance, asphalt surfaces can last up to 30 years, outliving tar surfaces that become brittle over time and require more frequent upkeep.
Health and Safety Differences
Working with asphalt and tar involves exposure to fumes and high temperatures. Asphalt emits fumes that can irritate the skin, eyes, and lungs. However, tar poses a greater health risk, especially coal tar, which contains carcinogenic polycyclic aromatic hydrocarbons (PAHs). The fumes are harsher, and the chemical burns more severe.
For these reasons, professional handling is advised for both materials, with asphalt being the safer choice as tar use declines.
Environmental Impact Differences
Neither material is environmentally benign, but tar is notably worse. Coal tar contains persistent pollutants like PAHs that can contaminate soil and water. Asphalt, while energy-intensive to produce, is more environmentally friendly due to its recyclability. Reclaimed Asphalt Pavement (RAP) reduces waste and the demand for new materials, positioning asphalt as the better choice for sustainability-conscious consumers.
Tips and Reminders for Choosing the Right Material
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Project Scope: Consider the scale and purpose of your project. For high-traffic areas, asphalt is generally more suitable.
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Budget: Assess your budget constraints. Tar and chip might offer cost savings but consider long-term maintenance expenses.
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Environmental Considerations: If sustainability is a priority, asphalt's recyclability is a distinct advantage.
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Health Concerns: For DIY enthusiasts, be aware of the health risks associated with each material, and consider hiring professionals.
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Longevity: Factor in the expected lifespan of the material and the maintenance it will require over the years.
Conclusion
Choosing between asphalt and tar depends on various factors, including your project's requirements, budget, and environmental considerations. While tar has historical significance, asphalt's durability, recyclability, and widespread use make it the preferred choice for most modern paving projects.
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Frequently Asked Questions
Is asphalt the same as tarmac?
No, asphalt and tarmac are distinct. Tarmac uses tar as a binder, while asphalt uses bitumen. Modern "tarmac" often refers to asphalt surfaces.
What’s the difference between tar and bitumen?
Tar is derived from heating organic materials, while bitumen is a petroleum product from crude oil refining. Both serve as binders, but bitumen is standard in current asphalt paving.
What is tar and chip?
A "tar and chip" surface uses liquid asphalt topped with stone chips, offering a textured, durable finish. Despite the name, modern applications use asphalt rather than tar.
How much does an asphalt driveway cost?
An asphalt driveway costs $7 to $13 per square foot for new installations and $8 to $15 per square foot for upgrades. Costs vary based on material and labor, with reclaimed asphalt offering savings.
How long does it take for asphalt to dry?
Asphalt dries in 24 to 72 hours for light traffic, with full curing taking three months to a year. During this period, avoid heavy loads to prevent marks.
By understanding the nuances between asphalt and tar, you can make informed decisions that align with your goals and values, paving the way for successful projects.