Get Perfect Driveways with Asphalt Millings Achieving Ideal Driveways Using Asphalt Millings

As an asphalt milling specialist with over 25 years of experience, I know that Asphalt millings are a cost-effective alternative to traditional paving materials, as they are recycled from old asphalt pavement and can be used in various construction projects such as road repairs, parking lots, driveways, and walkways. By reusing these materials, we reduce the demand for new asphalt and help conserve natural resources.

Additionally, asphalt millings are durable and long-lasting, capable of withstanding heavy traffic and harsh weather conditions. They also provide excellent drainage properties, reducing the risk of water pooling and potential damage to the pavement surface.

Milling Machine Specifications

Machine TypeMilling WidthMilling DepthProduction RateWeight
Cold Planer0.5 – 4.2 mUp to 330 mm200 – 800 t/h20 – 45 t
Micro-Milling Unit1.0 – 2.5 mUp to 75 mm150 – 400 t/h10 – 25 t
Rotary Cutter0.5 – 1.5 mUp to 150 mm100 – 300 t/h5 – 15 t

 

Asphalt Milling Properties

PropertyHot Mix Asphalt MillingsCold Mix Asphalt Millings
Aggregate Size9.5 – 25 mm4.75 – 19 mm
Binder Content4 – 6%2 – 4%
Fines/Dust Content2 – 5%5 – 10%
RAP PercentageUp to 30%Up to 50%
Typical ApplicationPavement OverlaysBase or Sub-base Layers

 

Cost Comparison of Asphalt Millings vs. Virgin Materials

MaterialCost per TonTransportation CostEnvironmental Impact
Asphalt Millings$10 – $25LowerReduced
Virgin Aggregates$20 – $40HigherHigher
Virgin Asphalt Binder$500 – $800HigherHigher

Production of Asphalt Millings by leveraging professional techniques

Milling Process width, depth, rate, and production

Road Construction

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Highway Construction7.2 m100 mm350 t/h28,000 tons
Freeway Expansion9.0 m75 mm400 t/h24,000 tons
Rural Road Development6.0 m60 mm200 t/h9,600 tons
Urban Street Repaving4.8 m50 mm150 t/h4,800 tons

 

Parking Lot Construction

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Commercial Parking Lots4.8 m75 mm180 t/h5,400 tons
Residential Parking Areas3.6 m50 mm120 t/h1,800 tons
Industrial Parking Facilities6.0 m100 mm240 t/h9,600 tons
Recreational Parking Spaces4.2 m60 mm150 t/h3,600 tons

 

Driveway Paving

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Residential Driveways3.0 m40 mm80 t/h120 tons
Commercial Driveways4.5 m60 mm120 t/h360 tons
Private Roadways6.0 m75 mm180 t/h1,800 tons

 

Airport Runway Repairs

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Taxiway Resurfacing22.5 m75 mm500 t/h15,000 tons
Runway Rehabilitation45.0 m100 mm800 t/h36,000 tons
Apron Maintenance30.0 m60 mm600 t/h9,000 tons

 

Bridge Deck Overlay

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Bridge Deck Repairs10.0 m50 mm200 t/h1,000 tons
Bridge Deck Replacements12.0 m75 mm300 t/h2,700 tons

 

Bicycle Path Construction

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Urban Bike Lanes2.4 m40 mm80 t/h960 tons
Recreational Cycling Trails3.0 m50 mm100 t/h1,500 tons

 

Pedestrian Walkway Paving

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Sidewalk Repairs1.8 m30 mm60 t/h540 tons
Pedestrian Mall Construction4.2 m60 mm140 t/h2,520 tons

 

Golf Course Pathways

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Cart Path Installation3.6 m50 mm120 t/h1,800 tons
Golf Course Maintenance4.8 m75 mm160 t/h3,600 tons

 Industrial Flooring

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Warehouse Floors6.0 m100 mm200 t/h6,000 tons
Factory Flooring4.8 m75 mm160 t/h3,600 tons

 

Sports Surface Construction

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Tennis Courts10.0 m50 mm200 t/h500 tons
Basketball Courts15.0 m60 mm300 t/h900 tons
Multi-purpose Sports Fields20.0 m75 mm400 t/h3,000 tons

 

Railroad Crossing Construction

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Roadway Crossings7.2 m75 mm240 t/h1,800 tons
Pedestrian Crossings4.8 m50 mm160 t/h600 tons

 

Utility Trench Patching

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Gas Line Repairs2.4 m40 mm80 t/h480 tons
Water Line Maintenance3.0 m50 mm100 t/h750 tons
Electrical Conduit Installations1.8 m30 mm60 t/h270 tons

 

Recreational Area Development

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Park Pavements4.2 m60 mm140 t/h2,520 tons
Playground Surfacing3.6 m50 mm120 t/h1,800 tons
Picnic Area Paving4.8 m75 mm160 t/h3,600 tons

 

Landfill Cap Construction

Project TypeMilling WidthMilling DepthMilling RateMillings Produced
Landfill Closure Projects6.0 m100 mm200 t/h12,000 tons
Environmental Remediation Sites4.8 m75 mm160 t/h4,800 tons

 

Equipment to Ensure Proper Millings

Milling Machines

In the asphalt milling process, specialized machines are used to remove the top layers of an existing pavement surface. These machines are designed to efficiently and precisely mill the material, producing high-quality asphalt millings for various applications.

Cold Planers

Cold planers, also known as milling machines or cold milling machines, are the most common type of equipment used for asphalt milling. These powerful machines feature a rotating drum equipped with cutting teeth that grind and remove the pavement surface. Cold planers are available in various sizes, ranging from compact units for small-scale projects to large, truck-mounted machines capable of milling widths up to 4.2 meters and depths up to 330 millimeters.

Cold Planers
Cold Planers

Micro-Milling Units

For projects requiring precise surface removal or texture modification, micro-milling units are employed. These smaller machines are designed for milling depths up to 75 millimeters and can achieve a finer, more uniform texture compared to traditional cold planers. Micro-milling units are particularly useful for applications like surface retexturing, removing surface irregularities, and preparing surfaces for thin overlays.

Micro-Milling Units
Micro-Milling Units

Rotary Cutters

Rotary cutters, also known as rotary milling machines, are another type of milling equipment used for asphalt removal. These machines feature a rotating drum with cutting teeth or picks that chip away at the pavement surface. Rotary cutters are typically smaller and more maneuverable than cold planers, making them suitable for confined spaces or areas with limited access.

Rotary Cutters
Rotary Cutters

Depth Control

Precise depth control is crucial in asphalt milling operations to ensure uniform removal and achieve the desired milling depth. Milling machines employ various depth control mechanisms, including:

Grade Control Systems:

These systems use sophisticated sensors and lasers to continuously monitor and adjust the milling depth based on the existing pavement profile.

Slope Control Technology:

This technology allows the milling machine to maintain a consistent cross-slope or crown during the milling process, ensuring proper drainage and surface geometry.

Depth Setting Mechanisms:

Most milling machines have manual or automated depth setting mechanisms that allow operators to precisely adjust the milling depth based on project specifications.

Material Collection

As the milling machine removes the asphalt surface, the resulting millings must be collected and transported for further processing or direct use. This is typically achieved through:

Conveyor Systems:

Milling machines are equipped with integrated conveyor systems that transfer the millings from the milling drum to a nearby truck or storage area.

Gathering Conveyors:

In some cases, additional gathering conveyors are used to collect the millings and load them onto trucks or into storage containers.

Loading Techniques:

Various loading techniques, such as direct loading into trucks or windrow loading, can be employed to efficiently collect and transport the asphalt millings.

Types of Millings

The milling process produces two main types of asphalt millings: hot mix asphalt millings and cold mix asphalt millings. These materials have distinct properties and applications.

Hot Mix vs. Cold Mix

The primary distinction between hot mix and cold mix asphalt millings lies in the temperature at which they are produced and processed.

Hot Mix Asphalt Millings

Hot mix asphalt millings are generated from the removal of hot mix asphalt (HMA) pavements. These millings retain a significant portion of the original asphalt binder and can be reheated and recycled into new asphalt mixes or used as a base material for pavement overlays.

Cold Mix Asphalt Millings

Cold mix asphalt millings are produced from the milling of cold mix asphalt (CMA) pavements, which are typically used for lower-volume roads or non-structural applications. These millings have a lower asphalt binder content and are often used as a base or sub-base material in pavement construction.

Application Differences

The properties and characteristics of hot mix and cold mix asphalt millings dictate their suitability for different applications.

Texture and Composition

Hot mix asphalt millings generally have a coarser texture and higher asphalt binder content, making them more suitable for applications that require structural strength and durability, such as pavement overlays or base layers.

Cold mix asphalt millings, on the other hand, have a finer texture and lower binder content, which makes them more suitable for applications where drainage and permeability are important, such as sub-base layers or erosion control measures.

Aggregate Size

The aggregate size distribution in asphalt millings can vary depending on the type of mix and the milling process. Hot mix asphalt millings typically contain larger aggregate sizes, ranging from 9.5 to 25 millimeters, while cold mix asphalt millings have smaller aggregate sizes, typically ranging from 4.75 to 19 millimeters.

Binder Content

The asphalt binder content is a crucial factor that influences the performance and properties of asphalt millings. Hot mix asphalt millings typically have a higher binder content, ranging from 4% to 6%, while cold mix asphalt millings have a lower binder content, ranging from 2% to 4%.

Fines and Dust Content

The amount of fines and dust present in asphalt millings can impact their performance and applications. Hot mix asphalt millings generally have a lower fines and dust content, ranging from 2% to 5%, while cold mix asphalt millings tend to have a higher fines and dust content, ranging from 5% to 10%.

Recycled Material Content

Asphalt millings can contain varying amounts of recycled materials, such as reclaimed asphalt pavement (RAP) or recycled asphalt shingles (RAS). Hot mix asphalt millings typically have a lower percentage of RAP, up to 30%, while cold mix asphalt millings may contain up to 50% RAP.

RAP Percentage

The percentage of RAP in asphalt millings can influence their properties and performance. Higher RAP percentages can result in a stiffer mix and potentially reduced durability, while lower RAP percentages may provide better workability and performance.

Recycled Binder Adjustment

When incorporating asphalt millings with higher RAP percentages into new mixes, it is important to adjust the amount of virgin asphalt binder to compensate for the aged binder in the RAP. This process, known as recycled binder adjustment, ensures that the overall binder content and properties meet the specified requirements.

Quality Control

Proper quality control measures are essential to ensure consistent performance and quality. This includes testing and monitoring properties such as gradation, binder content, and material composition. Regular sampling and testing during the milling process help maintain consistent material quality and ensure compliance with project specifications.

Applications of Asphalt Millings

Asphalt millings have a wide range of applications in various construction and environmental projects due to their cost-effectiveness, durability, and environmental benefits.

Pavement Overlays

One of the most common applications of asphalt millings, particularly hot mix asphalt millings, is in pavement overlays and rehabilitation projects.

Overlay Techniques

Asphalt milling can be incorporated into various overlay techniques, including:

Thin Overlays:

Millings are combined with virgin asphalt mix and placed as a thin overlay on existing pavements, providing a cost-effective solution for surface restoration.

Perpetual Pavements:

This approach uses millings as a base layer, while a thin asphalt overlay is applied on top, creating a long-lasting, low-maintenance pavement system.

Multi-layer Systems:

Millings can be used in multi-layer pavement systems, where different layers serve different structural and functional purposes.

Binding and Compaction

To ensure the proper performance of pavement overlays containing asphalt millings, proper binding and compaction techniques are crucial.

Tack Coats

Tack coats are light applications of asphalt emulsion or binder, are often used to promote adhesion between the asphalt milling layer and the overlying asphalt mix.

Roller Compaction

Adequate compaction is essential for achieving the desired density and performance of the asphalt milling layer. Various types of rollers, such as steel-wheeled, pneumatic-tired, or vibratory rollers, can be used to achieve the required compaction levels.

Temperature Control

For hot mix asphalt millings, temperature control during placement and compaction is crucial to ensure proper workability and performance. Monitoring and maintaining the appropriate temperature range helps achieve optimal compaction and long-term durability.

Performance Testing

To ensure the quality and longevity of pavement overlays containing asphalt millings, various performance tests may be conducted, including:

Load Bearing Tests

These tests evaluate the load-bearing capacity and structural integrity of the pavement system, ensuring it can withstand the anticipated traffic loads.

Weather Resistance Assessments

Asphalt millings are exposed to various weather conditions, so tests may be performed to assess their resistance to factors such as moisture, freeze-thaw cycles, and thermal cracking.

Longevity Studies

Long-term performance monitoring and longevity studies provide valuable insights into the durability and service life of pavement overlays containing asphalt millings, helping optimize future designs and maintenance strategies.

Environmental Rehabilitation

In addition to pavement applications, asphalt millings play a crucial role in various environmental rehabilitation projects, leveraging their cost-effectiveness, durability, and sustainable properties.

Erosion Control Methods

Asphalt millings are widely used in erosion control measures because they stabilize soil and prevent erosion caused by water or wind. Common applications include:

Slope Stabilization

Asphalt millings can stabilize slopes and embankments, providing a durable and cost-effective solution for preventing soil erosion and slope failures.

Ditch Lining

Lining drainage ditches with asphalt millings helps control erosion, maintain flow capacity, and prevent sediment accumulation.

Vegetative Support Structures

Asphalt millings can be used in constructing vegetative support structures, such as filter berms, which promote vegetation growth and prevent soil erosion.

Landfill Capping

The use of asphalt millings in landfill capping systems provides a cost-effective and durable alternative to traditional capping materials, while also promoting proper drainage and preventing erosion.

Layering Techniques

Various layering techniques can be employed when using asphalt millings for environmental rehabilitation projects, such as:

Permeability Control:

Adjusting the layer thickness and compaction levels can control the permeability of the asphalt milling layer, allowing for proper drainage or water retention as needed.

Regulatory Compliance:

Ensuring that the asphalt milling layers meet regulatory requirements for landfill capping, stormwater management, or other environmental applications.

Water Filtration Systems

Asphalt millings can be incorporated into water filtration systems, serving as filtration layers or flow regulation components.

Filtration Layers

In stormwater management systems, asphalt millings can be used as filtration layers, trapping sediments and pollutants while allowing water to pass through.

Flow Regulation

By controlling the permeability and porosity of asphalt milling layers, the flow of water can be regulated, promoting infiltration or directing runoff as needed.

Maintenance and Accessibility

One of the advantages of using asphalt millings in environmental rehabilitation projects is the ease of maintenance and accessibility. Asphalt milling layers can be easily repaired or resurfaced as needed, ensuring long-term performance and cost-effectiveness.

The production and application of asphalt millings have become increasingly important in the construction and environmental industries, offering cost-effective and sustainable solutions for various projects. By understanding the milling process, the different types of millings, and their diverse applications, professionals can make informed decisions and optimize the use of these valuable materials.

Whether it’s pavement overlays, erosion control measures, or environmental rehabilitation projects, asphalt millings provide numerous benefits, including cost savings, durability, and reduced environmental impact. As the demand for sustainable and cost-effective solutions continues to grow, the role of asphalt milling is poised to become even more significant in the years to come.

Last Words and Key Takeaways

Remember, the key to success lies in understanding the milling process, the differences between hot mix and cold mix asphalt millings, and their specific applications. Proper quality control, material selection, and construction techniques are crucial for ensuring the long-term performance and longevity of projects involving asphalt millings.

I encourage all professionals in the field to explore the versatility of asphalt millings and embrace their numerous applications, from pavement overlays to environmental rehabilitation projects. By doing so, we can contribute to a more sustainable and cost-effective future for our industry, while minimizing our environmental impact.

About Author

Steve Axton is an Asphalt Milling Specialist & Consultant with over 25 years of experience in civil engineering, specializing in road surface technologies. His expertise lies in the production, application, and performance evaluation of asphalt millings. Throughout his career, Steve has been at the forefront of promoting sustainable and cost-effective solutions in the construction industry, advocating for the responsible use of recycled materials and environmentally friendly practices.

Resources for Asphalt Millings, each with a hyperlinked anchor text:

  1. Federal Highway Administration: Recycled Asphalt Millings – Information from the FHWA on the use of asphalt millings in various construction applications.
  2. Missouri Department of Transportation: Asphalt Millings Fact Sheet – A fact sheet from MoDOT on the benefits and applications of asphalt millings.
  3. Illinois Department of Transportation: Asphalt Millings for Shoulders and Bases – A guide from IDOT on the use of asphalt millings for shoulder and base construction.
  4. North Carolina Department of Transportation: Recycled Asphalt Millings – A resource from NCDOT on the specifications and guidelines for using recycled asphalt millings.
  5. Minnesota Pollution Control Agency: Best Practices for Asphalt Millings – A publication on the best practices for managing and using asphalt millings while minimizing environmental impact.
  6. California Department of Transportation: Recycled Asphalt Millings – Information from Caltrans on the use of recycled asphalt millings in various construction projects.
  7. Texas Department of Transportation: Asphalt Millings Specification – A specification document from TxDOT on the requirements for using asphalt millings in construction projects.
  8. Pennsylvania Department of Transportation: Asphalt Millings in Construction – A publication from PennDOT on the use of asphalt millings in various construction applications.
  9. New York State Department of Transportation: Asphalt Millings Guidance – A guidance document from NYSDOT on the proper handling and use of asphalt millings.
  10. U.S. Environmental Protection Agency: Asphalt Millings in Construction – Information from the EPA on the use of asphalt millings as a recycled material in construction projects.
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I'm Steve Axton, a dedicated Asphalt Construction Manager with over 25 years of experience paving the future of infrastructure. My journey with asphalt began by studying civil engineering and learning about core pavement materials like aggregate, binder and additives that compose this durable and versatile substance. I gained hands-on experience with production processes including refining, mixing and transporting during my internships, which opened my eyes to real-world uses on roads, driveways and parking lots. Over the past decades, I have deepened my expertise in asphalt properties like viscosity, permeability and testing procedures like Marshall stability and abrasion. My time with respected construction companies has honed my skills in paving techniques like milling, compaction and curing as well as maintenance activities like crack filling, resurfacing and recycling methods. I'm grateful for the knowledge I've gained about standards from Superpave to sustainability best practices that balance longevity, cost and environmental friendliness. It's been an incredibly rewarding career working with this complex material to build the infrastructure future.

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