Asphalt Materials Are The Future of Self-Healing Road Construction

A brief introduction to Asphalt materials

Roofs and highways predominantly utilize asphalt materials due to their hardness and resistance to extreme pressure and friction. Aggregates and binders are the two primary parts of asphalt materials. Crude oil or naturally occurring deposits serve as the raw materials for producing binders. Meanwhile, aggregates, constructed from broken rocks, sand, and gravel, make up the majority of the mixture. The quality of the aforementioned components strongly influences the durability, performance, strength, stability, flexibility, and drainage of the final product. Compared to other materials with similar features, Asphalt is affordable, widely available, and weather resistant making it undeniably the best material over competitors such as gravel, tarmac and macadam for road construction.

Major disadvantage of using Asphalt

Regular maintenance is essential for asphalt materials since they are susceptible to temperature changes, rain runoff, and cracking and fissures as they age. Thus, asphalt’s structural integrity changes with time. Consequently, managing and maintaining roads comes at a cost of millions of dollars. Various experts have proposed several solutions to address the expensive maintenance.

  • Self-healing Asphalt
  • Improved traditional Asphalt
  • Enhanced low cost maintenance and repair techniques

We haven’t used better conventional asphalt for a sufficient duration to assess its efficacy fully. Consequently, its effectiveness remains uncertain. Despite enhancements, conventional asphalt may still struggle to seal every crack and break in the road. Furthermore, it is preferable to have no repairs than few, inexpensive ones. For this reason, self-healing asphalt is still the best choice in the present situation.

Self-healing Asphalt materials

Self-healing asphalt is an exciting development in road construction that aims to address the cracks and damages on asphalt surfaces. Current manufacturing approaches for self-healing asphalt are as follows.

  1. Microencapsulation: Microscopic capsules embedded in asphalt contain rejuvenators, bitumen, or polymers. The healing chemical seeps into the fracture and fills it, thus “sealing” the wound, as the capsules burst open.
  2. Intrinsic healing: Using unique chemicals, this method alters the asphalt itself to enable it to mend minor fractures on its own. These additives might be polymers that, when heated by sunshine or traffic, alter viscosity with temperature, allowing them to flow and fill gaps.
  3. Induction heating: Mix steel fibres with asphalt and utilize an external induction heating source to melt the surrounding asphalt when a fracture occurs, thereby closing the crack by “welding” it.
  4. Microvascular networks: Tiny tubes embedded in the asphalt contain healing chemicals. The agent promotes healing by moving through the network to the injured location when a crack appears.
  5. Bio-based techniques: Inspired by the body’s inherent wound-healing mechanisms, scientists are investigating the use of bacteria or enzymes that might encourage self-healing inside the asphalt.

Benefits and applications

The potential benefits of self-healing asphalt are numerous:

  • Reduced maintenance costs: By automatically repairing minor damage, self-healing asphalt can significantly reduce the need for frequent patching and repairs, leading to substantial cost savings.
  • Improved road safety: Self-healing properties can prevent small cracks from developing into larger potholes, which pose a safety hazard for drivers.
  • Extended pavement lifespan: By addressing damage early on, self-healing asphalt can extend the overall lifespan of the pavement, reducing the need for costly replacements.
  • Environmentally friendly: Reduced maintenance and extended lifespan translate to lower energy consumption and raw material use, contributing to a more sustainable infrastructure.

While still under development and field testing, self-healing asphalt holds promise for various applications, including:

  • High-traffic roads and highways: These pavements experience significant wear and tear, making them ideal candidates for self-healing properties.
  • Airports and runways: Maintaining smooth and crack-free surfaces is crucial for safety in these critical transportation hubs.
  • Bridge decks and other structures: Self-healing asphalt can protect these structures from water infiltration and extend their service life.

Challenges and Future

Despite its potential, self-healing asphalt still faces some challenges:

  • Cost: The addition of healing agents can increase the initial cost of the asphalt mixture.
  • Durability: The long-term effectiveness of the healing agents under real-world conditions needs further evaluation.
  • Standardization: Establishing industry standards and performance testing protocols for self-healing asphalt is crucial for wider adoption.

Nonetheless, these issues are being addressed by continued study and development. Standardized testing procedures are being developed, and new healing agents with enhanced efficacy and cost-effectiveness are being investigated. In the future, self-healing asphalt should become a more popular option for durable and sustainable pavements as costs come down and technology progresses.

Sources: https://www.mdpi.com/1996-1944/15/10/3672

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