Are you dealing with a dusty asphalt millings driveway or parking lot that seems to create clouds of dust every time vehicles pass over it? Or perhaps you’ve noticed that your recently installed asphalt millings surface isn’t holding together as well as you’d hoped? These are common challenges with recycled asphalt surfaces, but with the right treatment, you can significantly improve their performance and appearance.
Asphalt millings offer an economical and environmentally friendly alternative to traditional asphalt paving, but they often require additional treatment to reach their full potential. The right spraying solution can transform loose, dusty millings into a stable, low-maintenance surface that serves your property for years to come.
In this comprehensive guide, we’ll explore the various products you can spray on asphalt millings to control dust, improve binding, and enhance longevity. We’ll compare professional-grade solutions with DIY options and provide practical application advice for both residential and commercial property owners.
Understanding Asphalt Millings and Their Challenges
Asphalt millings (sometimes called recycled asphalt pavement or RAP) are created when existing asphalt is removed and processed during road rehabilitation projects. The old asphalt is ground up into small, gravel-like pieces that can be reused for various applications, including driveways, parking lots, and rural roads.
While asphalt millings offer several advantages including:
- Lower cost compared to new asphalt paving
- Environmental benefits through recycling existing materials
- Good drainage properties
- Excellent stability once properly compacted
They also come with inherent challenges:
- Dust generation, especially in dry conditions
- Loose surface particles that can scatter
- Vulnerability to erosion during heavy rain
- Reduced binding compared to hot-mix asphalt
These challenges make proper treatment essential. Without appropriate binding agents or dust suppressants, asphalt milling surfaces can deteriorate quickly, creating ongoing maintenance issues and potentially shortening their useful lifespan.
Dust Control Solutions for Asphalt Millings
Dust from untreated asphalt millings can be more than just a nuisance—it can create visibility hazards, affect air quality, and eventually lead to material loss from your surface. Here are the most effective dust control options for asphalt millings:
Water Application
The simplest and most temporary solution is water. Regular sprinkling can keep dust down, but its effects are short-lived, especially in hot, dry climates like Arizona. Water is best used as a stop-gap measure or in combination with other treatments.
Pros: Inexpensive, readily available, environmentally safe
Cons: Very temporary (hours at most), requires frequent reapplication
Calcium Chloride
This chemical compound draws moisture from the air, keeping the surface damp and dust-free for extended periods. It’s particularly effective in areas with at least 30% relative humidity.
Pros: Longer-lasting than water (2-4 weeks per application), works at lower temperatures
Cons: Can be corrosive to metal, may harm nearby vegetation, effectiveness decreases in very dry conditions
Magnesium Chloride
Similar to calcium chloride but generally less corrosive, magnesium chloride is another effective dust suppressant that works by attracting moisture from the air.
Pros: Less corrosive than calcium chloride, effective for 4-6 weeks per application
Cons: Performance drops in extremely dry conditions, slightly more expensive than calcium chloride
Organic Dust Suppressants
These include lignin derivatives (from paper manufacturing), vegetable oils, and molasses-based products. They bind smaller particles together and create a crust-like surface.
Pros: Environmentally friendly, non-corrosive, can last 1-3 months
Cons: May require more frequent reapplication in high-traffic areas, can be more expensive than chloride-based options
For optimal dust control results, application timing matters. Treat surfaces in early morning or evening when temperatures are lower and humidity is higher. This allows better penetration and more effective binding.
Binding Agents and Sealers
While dust suppressants primarily address airborne particles, binding agents and sealers work to stabilize the entire asphalt millings surface, creating a more cohesive and durable result.
Liquid Asphalt Emulsions
These products—including MC-30, CSS-1h, and MS-1—consist of asphalt particles suspended in water with an emulsifying agent. They penetrate the millings and create bonds between particles as they cure.
Pros: Excellent binding properties, creates a more traditional asphalt-like surface, weather-resistant
Cons: Require specific application equipment, proper temperature conditions for application
Asphalt Rejuvenators
These specialized products restore the chemical properties of aged asphalt, effectively “reactivating” the binder in recycled asphalt millings.
Pros: Enhances the natural binding qualities already present in millings, extends surface life
Cons: More expensive than basic treatments, works best on higher-quality millings with good binder content
Commercial Sealers
Various commercial products specifically formulated for asphalt millings combine binding and sealing properties. These often contain a mix of asphalt emulsion, polymers, and other additives designed to enhance performance.
Pros: Convenient pre-mixed formulations, consistent results, often include warranty
Cons: Higher cost than generic options, may require professional application for larger areas
When selecting a binding agent, consider your traffic load and weather conditions. Heavier traffic and extreme temperature fluctuations call for more robust binding solutions with added polymers or reinforcing agents.
Application Methods and Best Practices
Proper application is just as important as choosing the right product. Follow these guidelines to ensure optimal results:
Surface Preparation
- Ensure proper compaction of asphalt millings (ideally with a vibratory roller)
- Remove loose debris and sweep the surface clean
- Fill significant depressions or uneven areas
- Allow the surface to dry if previously wet
Application Equipment
For smaller residential applications, you might use:
- Pump sprayers for dust suppressants
- Asphalt squeegees or brushes for sealers
- Garden sprayers with appropriate nozzles
Commercial applications typically require:
- Distributor trucks with spray bars
- Pressurized spray systems
- Commercial sealcoating equipment
Application Rates
Follow manufacturer guidelines, but general recommendations include:
- Dust suppressants: 0.25-0.5 gallons per square yard
- Liquid asphalt emulsions: 0.3-0.7 gallons per square yard
- Commercial sealers: As specified by the product (typically 0.1-0.2 gallons per square yard)
Multiple Coat Strategy
For optimal results, consider a two-phase approach:
- Initial penetrating application at a higher dilution rate to achieve depth
- Surface sealing application at a lower dilution rate to create a protective top layer
Allow sufficient drying time between coats (typically 24-48 hours, depending on weather conditions).
Weather Considerations
- Ideal application temperature: 50-90°F (10-32°C)
- Avoid application during rain or when rain is expected within 24 hours
- Avoid extreme heat which can cause too-rapid drying and improper curing
- Allow adequate curing time before allowing traffic (typically 24-72 hours)
Professional vs. DIY Application
While DIY application is possible for smaller residential projects, commercial properties often benefit from professional asphalt contractor services.
DIY Considerations
Suitable for: Small driveways, rural pathways, limited-use areas
Advantages: Cost savings, flexibility in timing, no contractor scheduling
Challenges: Equipment limitations, potential for uneven application, time investment
Professional Application
Recommended for: Commercial parking lots, high-traffic areas, larger residential properties
Advantages: Specialized equipment for even application, expertise in product selection, time efficiency, often includes warranties
Investment: Higher initial cost but potentially better long-term value
The decision often comes down to scale and performance expectations. A professional application from an experienced asphalt contractor typically provides more consistent results and longer-lasting performance, particularly for commercial properties where appearance and durability are paramount.
Maintenance and Reapplication Guidelines
Even the best treatments will require maintenance over time. Here’s what to expect:
- Dust suppressants: Reapplication every 1-6 months depending on product, traffic, and weather conditions
- Binding agents: Reapplication every 1-3 years depending on quality and traffic
- Sealers: Reapplication every 2-5 years
Watch for these signs that reapplication is needed:
- Increasing dust levels
- Surface raveling (loose particles appearing)
- Color fading from black/dark gray to light gray
- Water no longer beading on the surface
In Arizona’s climate, consider scheduling maintenance in spring or fall to avoid extreme summer temperatures that can affect application quality.
Treating asphalt millings with appropriate dust control and binding agents transforms a good recycled product into an excellent paving solution. The right treatment not only reduces dust and improves appearance but significantly extends the surface’s useful life, protecting your investment.
For commercial properties in particular, professional application of high-quality binding products offers the best long-term value and performance. ALK Asphalt specializes in asphalt milling installation and treatment throughout Phoenix and Sun City, bringing over 60 years of combined experience to every project.
Ready to improve your asphalt millings surface with professional treatment? Contact ALK Asphalt today at (602) 218-4997 for a consultation and personalized recommendation for your property’s specific needs.
