Asphalt Millings Paving Construction DIY, Roadwork, Project Estimation.

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1. Introduction to Asphalt Millings

Asphalt milling refers to the recycled material produced when deteriorated asphalt pavement is removed and reclaimed through a process called milling. The milling process uses a machine to grind off the top layer of asphalt down to a desired depth. The removed material, or reclaimed asphalt pavement (RAP), can then be reused in various construction applications. Asphalt millings provide an economical and sustainable pavement material option.

Fact Details
Other Names Reclaimed asphalt pavement (RAP), milled asphalt
Production Method Milling with specialized equipment
Typical Size 1/2 to 2 inches
Composition Milled old asphalt
Appearance Black aggregates with some fine material
Primary Uses Base course, driveways, shoulders, trails


Asphalt Paving Guide to Planning, Design, and Construction

2. Benefits of Using Asphalt Millings

Asphalt millings offer many advantages that make them a prime recycled material choice:


Provides substantial cost savings over virgin aggregate

Reuses waste

Recycles existing asphalt that would otherwise go to landfills


Can be used in many applications with proper preparation


Compacts into a strong, stable finished surface

Low Dust

Binds together better than gravel, minimizing dust


Produced in large quantities by numerous milling projects


Conserves natural resources and landfill space

Driveway Sealer Calculator Determining Required Materials for Asphalt Driveway Sealcoating Projects

3. Potential Uses of Asphalt Millings

Due to their versatile properties, asphalt millings can serve a range of construction functions:

Use Details
Driveways/Parking Lots Durable, low dust surface; needs grading
Road Base Stabilized millings make an excellent flexible base course
Shoulders Can build up and reinforce soft shoulders
Trails/Paths Smooth, solid surface for walking, biking, horses
Landscaping Decorative mulch around trees and beds
Temporary Roads Quick access over unpaved areas


Installing Crushed Asphalt Walkways, Paths and Trails

Gradation of Miller Asphalt

The particle size distribution, or gradation, of milled asphalt, can vary substantially depending on the properties of the original pavement. Here are typical size fractions:

Sieve Size % Passing
1 inch 95-100%
3/4 inch 70-95%
3/8 inch 60-85%
#4 45-70%
#100 5-25%

Controlling the gradation by screening helps create better-performing finished surfaces. Removing excess fines prevents dust and instability.

5. Compaction Recommendations

Proper compaction of milled asphalt is crucial for strength and durability:

  • Target density of 95% Proctor density for stability
  • Use a pneumatic tire roller for breakdown
  • Finish with a vibratory steel drum roller
  • Add moisture if needed to reach an optimum level
  • Compact in 6-inch lifts until the desired depth is reached

Higher densities greatly improve the performance of traffic surfaces constructed with asphalt millings.

6. Uses Over Gravel

Compacted asphalt millings provide far superior surfacing compared to gravel roads and drives:

Factor Millings Gravel
Strength Higher Lower
Dust Control Excellent Poor
All-Weather Excellent Poor
Smoothness Good Fair
Cost Low Medium

Asphalt millings can readily be placed directly over an existing gravel surface. This caps the gravel and binds it together into a stronger stabilized layer.

Asphalt Batch Size Calculator for Efficient Production Planning

7. Best Practices for Use Over Gravel

To successfully use asphalt millings over gravel:

  • Ensure gravel substrate is compacted and stable
  • Grade and crown gravel for proper drainage
  • Spread a 3-4 inch uniform layer of millings
  • Compact with roller to lock millings together
  • Add 1-2 inch fresh layer and recompact
  • Fill potholes with additional millings as needed
  • Re-grade periodically to maintain shape

Proper preparation and installation procedures create a durable, long-lasting surfacing.

8. Environmental Benefits

Utilizing recycled asphalt millings provides noteworthy environmental advantages:

  • Conserves virgin aggregates like crushed stone
  • Provides an outlet for reclaimed asphalt rather than landfilling
  • Reduces trucking needs and associated emissions
  • Recycling extends the service life of raw materials
  • Reuses existing pavement rather than new mixes
  • Lower energy inputs than the creation of new hot mix asphalt

9. Common Concerns and Considerations

Some common concerns when using asphalt milling include:

Issue Mitigation
Stockpile Segregation Use best practices to minimize segregation
Excess Fines Screen and remove fines as needed
Contaminants Ensure millings are free of debris before use
Lack of Binders Add emulsion or foamed asphalt to increase cohesion
Dust Control Use water, compaction, and surface sealing

Typical Asphalt Milling Equipment

Equipment Description
Cold Planer Large milling machine rotates grinding drum to remove asphalt
Skid Steer Smaller mill attachment for skid steers in tight areas
Front End Loader Scoops and loads milled material into trucks
Dump Truck Hauls millings from project site to storage or reuse site
Pneumatic Roller Compacts millings with rubber tires for breakdown
Steel Drum Roller Provides final compaction of millings with vibratory drum

12. Milling Production Rates

Milling Depth Production Rate
1 inch 600-800 square yards per hour
2 inches 400-600 square yards per hour
3 inches 300-500 square yards per hour
4 inches 250-400 square yards per hour
5 inches 200-350 square yards per hour

Rates depend on machine size, material properties, and site conditions.

13. Asphalt Milling Emission Reduction

Asphalt milling produces substantially lower emissions compared to alternative removal methods:

Method Relative Emissions
Cold Milling Low Emissions
Hot In-Place Recycling Moderate Emissions
Full-Depth Removal High Emissions

Milling produces little heat or fumes since it operates at ambient temperatures.

14. Uses as Stabilized Base Layer

Mixed with emulsified or foamed asphalt, RAP makes an excellent stabilized base:

Feature Benefit
Strength Provides structural support for pavement
Flexibility Resists cracking better than cement
Water Resistance Maintains strength when wet
Affordability More economical than virgin aggregate

Stabilized RAP provides excellent pavement base properties.

15. Seasonal Considerations

Season Effects
Summer Higher temperatures aid compaction. Dust control is needed.
Winter May not compact well when frozen. Can be used below freezing if protected.
Wet Periods Water spray aids compaction. Drainage is important.
Dry Spells Water application prevents segregation during handling and laydown.


10. Sourcing Asphalt Millings

There are several options for sourcing asphalt millings at reasonable cost:

  • Check for local ads or listings for free/cheap milling
  • Contact paving companies directly about excess RAP
  • Connect with municipalities and transportation departments
  • Time requests for early summer when most milling occurs
  • Be willing to transport millings or pay nominal hauling fees
  • Request clean, screened material for the best quality

With some research and outreach, quality recycled asphalt millings can be acquired to suit almost any project need. Their versatility and advantages make them a prime “green” pavement material.

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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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