Intelligent Compaction for Hot Mix AsphaltMike Arasteh, RC Baltimore

IC for Hot Mix Asphalt

Washington DC circa 1900

Our Objectives

• Why IC for HMA?• HMA-IC Advantages,• Equipment,• Benefits,• Lessons Learned,• Generic Specification, and• How to Specify IC.

Why IC for Hot Mix Asphalt?

Shortcomings in the Compaction Process…

Limited “On The Fly” Feedback

Over or Under-Compaction Can Occur

Photos courtesy of each company

Shortcomings in Density Acceptance Process…

Limited Number of Locations

After Compaction is Complete

Why IC for Hot Mix Asphalt?

HMA-IC Advantages

• IC offers many advantages over conventional compaction equipment,

• IC offers valuable new tools to the contractor to improve Quality Control, and

• IC offers valuable new tools to the owner/agency to improve pavement service life.

IC for Hot Mix Asphalt

An Innovation in Compaction Control and Acceptance

Photos courtesy of each company

Tandem Drum IC RollersBomag

Caterpillar Sakai

HAMM-WirtgenPhotos courtesy of each company

Sakai Double Drum IC System

Temperature Sensor

GPS Radio/Receiver

Control Panel

Accelerometer CIS Display

Photos courtesy of each company

HAMM Double Drum IC System

Accelerometer

GPS Receiver

HCQ GPS Navigator

Temperature Sensors Control Panel

Photos courtesy of each company

Benefits of IC for HMA

• Improve density….Better Performance• Improve efficiency….Cost Savings• Increase information…Better QC/QA

• Overall Benefit:

Improved Pavement Performance!

• Use and acceptance by roller operators• Improved roller patterns / passes• Use of IC rollers for “mapping” of underlying

materials (Soils, GAB, Existing Asphalt Pavements)

• Underlying support affects compactability of subsequent layer

• Correlations of RMV to in situ test results is challenging

Lessons Learned

Lessons Learned

• While correlation is better for granular materials, poor correlation for HMA

• Many variables that can adversely affect correlation– Mat temperature (min. 220º F?)– Mat temperature variations– Depth of measurement– Underlying material support / variability– Accuracy / calibration of density gauges

• The correlation between ICMV and FWD/LWD-based deflections or moduli indicates a better linear correlation

• ICMV values do not factor in mat temperature, which can affect in situ test results

• Using multi-linear regression has improved the correlation analysis between ICMVs and in-situ spot tests

Lessons Learned

Generic IC Specifications

• Equipment– Rollers– GPS

• Equipment Setup and Verification• Technical Support• Quality Control Plan• Establishment of Target Value• IC Construction

How to Specify IC

• Modify generic IC specs to fit your agency• Include IC specifications in your contract• Specifications make Contractor responsible for:

– Obtaining IC rollers, GPS and technical support– Setup a IC data management system– Developing a QC Plan which incorporates IC

equipment and data in construction process• (continue on next page)

How to Specify IC (cont’d)

• Specifications make Contractor responsible for:– Conduct a test strip to establish a roller pattern

and a ICMV target value– Construct materials using IC rollers

• Daily verification of GPS roller location and data collection

• Daily collection, storage and analysis of data• Report compliance with IC specifications