Intelligent Compaction for Hot Mix Asphalt Mike 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 Rollers Bomag Caterpillar Sakai HAMM-Wirtgen Photos courtesy of each company

Sakai Double Drum IC System Temperature Sensor GPS Radio/Receiver Control Panel AccelerometerCIS 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

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