Porous Asphalt

Porous Asphalt Paving

What is Porous Asphalt?

Porous asphalt is an innovative paving material designed to mimic the natural water infiltration process of undisturbed soil. Unlike traditional impermeable asphalt, porous asphalt allows rainwater to seep through its surface and into the underlying layers, reducing stormwater runoff and mitigating its impact on the environment.

The porous asphalt course typically ranges from 2 to 4 inches in thickness and contains approximately 16% voids, significantly higher than traditional asphalt. This void space allows rainwater to rapidly penetrate the pavement, reducing surface runoff and improving water quality.

Cost of Porous Asphalt

Porous asphalt typically carries a higher upfront cost compared to traditional asphalt, with material costs alone being 20-50% more expensive due to the specialised composition required for permeability. However, it’s essential to consider the long-term benefits and potential cost savings.

Initial Costs: The increased cost is attributed to the need for specific aggregates and additives that create the open-graded structure necessary for effective water infiltration. This structure requires careful engineering and precise application to ensure its effectiveness.

Long-Term Benefits and Savings

Stormwater Management: Porous asphalt significantly reduces or eliminates the need for costly stormwater management infrastructure such as detention basins and retention ponds. By naturally managing stormwater on-site, it can save substantial expenses related to stormwater control and treatment.
Land Utilisation: The elimination of extensive stormwater management systems allows for more efficient land use, potentially increasing the value and utility of the property.
Environmental Savings: By reducing surface runoff, porous asphalt helps to minimise erosion and improve water quality, contributing to environmental cost savings. These benefits can lead to reduced regulatory compliance costs and potential incentives for sustainable practices.
Maintenance and Durability: Properly installed and maintained porous asphalt can have a long service life, often exceeding 20 years. This durability reduces the frequency and cost of repairs and replacements.

Value Proposition

While the initial investment for porous asphalt is higher, the long-term value proposition often justifies the added expense. The combination of reduced stormwater infrastructure costs, environmental benefits, and potential land-use efficiencies make porous asphalt a cost-effective solution for many projects. It provides both immediate and long-term savings, making it an attractive option for sustainable development and infrastructure improvements.

Benefits of Porous Asphalt

Reduces Surface Water Runoff

By allowing water to pass through the pavement, porous asphalt reduces surface runoff and the risk of flooding.

Improves Drainage

The high void content in the asphalt allows for efficient water filtration through the pavement structure into an underlying drainage base, enhancing overall drainage.

Enhances Groundwater Recharge

Facilitates the natural process of groundwater recharge, reducing the impact on stormwater systems.

Cost-Effective Stormwater Management

Eliminates the need for traditional stormwater management solutions like retention ponds, freeing up land for other profitable uses.

Environmental Benefits

Reduces energy consumption and greenhouse gas emissions during production and placement compared to hot mix asphalt.

How porous asphalt works

Porous asphalt pavements are designed with high void content, enabling water to filter through the pavement structure. This water then enters an underlying drainage base and eventually the water table, protecting both the subgrade and the pavement structure itself. This design contrasts with traditional asphalt, which is engineered to minimise water infiltration to prevent damage to the pavement layers.

Porous asphalt systems include several layers:

Top Filter Course: A 2-inch thick layer using 1/2-inch crushed stone aggregate, providing filtration and protecting the reservoir course during asphalt placement.
Porous Asphalt Course: The main layer, which is 2-4 inches thick, consisting of open-graded asphalt with high void content.
Reservoir Course: Acts as a storage layer for stormwater, often made of larger aggregate.
Optional Bottom Filter Course: Provides additional filtration if necessary.
Filter Fabric: Prevents soil migration into the aggregate layers.
Existing Soil/Subgrade: The natural ground that supports the entire structure.

Common Uses of Porous Asphalt

Porous asphalt is increasingly being adopted due to its environmental benefits and effectiveness in managing stormwater runoff. Its versatility makes it suitable for a variety of applications, including:

Parking Lots

A popular choice for both residential and commercial properties, porous asphalt helps reduce flooding and improve water quality. By allowing water to permeate through the surface, it minimises surface runoff and reduces the burden on stormwater systems.

Driveways

Porous asphalt provides a safe and attractive surface for pedestrians while allowing rainwater to infiltrate. This helps to prevent puddling and enhances the safety and usability of walkways.

Bike Paths

Ideal for cycling paths, porous asphalt offers good traction and helps prevent water accumulation. This makes it a safer and more reliable surface for cyclists, particularly in wet conditions.

Sidewalks and Walkways

Porous asphalt provides a safe and attractive surface for pedestrians while allowing rainwater to infiltrate. This helps to prevent puddling and enhances the safety and usability of walkways.

Playgrounds

A safe and sustainable option for children's play areas, porous asphalt provides a durable surface that manages stormwater effectively, reducing the risk of puddles and slippery surfaces.

Road Shoulders

Porous asphalt can be used to manage stormwater runoff from roadways, helping to prevent erosion and maintain the integrity of the road structure.

Urban Areas

Porous asphalt is ideal for urban areas prone to flooding, helping to manage excess stormwater. Its use in city environments can alleviate pressure on municipal stormwater systems and reduce the risk of urban flooding.

Environmentally Sensitive Areas

Suitable for locations requiring sustainable and eco-friendly solutions, porous asphalt minimises environmental impact by enhancing natural groundwater recharge and reducing surface runoff.

Important Considerations

While porous asphalt is suitable for many applications, it may not be ideal for areas with heavy traffic or extreme weather conditions. The design and implementation must consider the specific requirements and limitations of the location to ensure optimal performance and longevity.

Porous asphalt’s ability to manage stormwater efficiently while providing a durable and safe surface makes it an excellent choice for various applications, contributing to sustainable development and improved environmental outcomes.

Design and Maintenance Considerations

To ensure optimal performance and longevity of porous asphalt pavements, several design and maintenance factors must be considered:

Highly Permeable Soils: Placement in areas with highly permeable soils enhances the system’s effectiveness.
Vacuum Sweeping: Regular vacuum sweeping, ideally quarterly, to maintain permeability.
Heavy Vehicle Restrictions: Limiting use by heavy vehicles to prevent damage.
De-Icing Chemicals: Limited use to prevent clogging of the porous structure.
Runoff Pretreatment: Implementing a pretreatment plan for runoff to reduce sediment load.

Frost Line Consideration: Extending the reservoir depth below the frost line to prevent frost heave.

The Benefits and Potential of Porous Asphalt

Porous asphalt is a revolutionary paving solution that addresses stormwater management challenges while offering environmental and economic benefits. By reducing surface runoff, enhancing groundwater recharge, and eliminating the need for traditional stormwater infrastructure, porous asphalt is ideal for urban areas, parking lots, driveways, and environmentally sensitive regions. Proper installation and maintenance ensure its longevity and effectiveness, making it a valuable investment for sustainable infrastructure.

Why Choose Us

Whitleah Asphalt is a family-owned business specialising in residential, commercial, government and council. No job is too big or too small.

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WORKING WITH WHITLEAH ASPHALT

EXPERIENCE & EXPERTISE

With over 20 years of industry experience, Whitleah Asphalt has built a reputation for excellence in asphalt paving. Our team of skilled professionals brings a wealth of knowledge and expertise to every project, ensuring high-quality workmanship and outstanding results.

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At Whitleah Asphalt, we prioritise quality in every aspect of our work. Our attention to detail and adherence to industry standards ensure that each project is completed to the highest specifications. We are dedicated to exceeding our clients’ expectations and achieving complete customer satisfaction. Our commitment to quality is reflected in our ISO certifications in Environmental Management (ISO 14001), Safety Management (ISO 45001), and Quality Management (ISO 9001).

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As a locally owned and operated business, we have an in-depth understanding of the Central Coast and Hunter region. This local knowledge allows us to provide tailored solutions that meet the specific needs of our clients. Whether it’s a small residential driveway or a large commercial project, we offer customised services designed to deliver optimal results.

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