Talking Asphalt: Intelligent Compaction – March 2012

Talking Asphalt Dwight Walker

In February’s blog, I shared some thoughts on density and its importance. That column mentioned that there is a new tool, Intelligent Compaction (IC), to aid in monitoring and achieving compaction. I want to share a little bit about IC. I believe this new technology is well worth looking at. Anything that improves compaction and density deserves consideration.

IC is a computerized measuring system mounted on-board the roller which allows the operator to monitor the progress of compaction while there is time to make changes. IC rollers can be used on soils, aggregate bases and asphalt. IC systems include an integrated measurement system, a mapping system using the Global Positioning System (GPS), and an on-board computer recording and reporting system. The mapping display shows the number of passes that have been applied, allowing more uniform and consistent compaction. Some IC-equipped rollers can automatically change the compactive effort based on stiffness measurements.

IC rollers provide information to help the operator do a better job. However, they do cost more (one estimate I saw said about 20 percent more). But savings may be realized in having more efficient rolling patterns (by avoiding unnecessary over-compaction) and by using the in-process information to avoid penalties and, perhaps, earning more bonuses.

IC is a rapidly evolving technology that is being studied and implemented by highway agencies in the U.S. To assist in the introduction of IC, a major research project was conducted on field projects across the country. This Intelligent Compaction Pooled Fund (ICPF) project was completed in 2011. The focus has now shifted to targeted research projects to address gaps in the knowledge base and to further implementation efforts.

The major finding of the ICPF study is that Intelligent Compaction is now ready to begin being implemented as a quality control tool, but it is not ready to be used as an acceptance test at this time. FHWA is currently conducting several national IC workshops in various regions of the country. These workshops are designed to summarize the results and findings of the ICPF effort and to present generic guide specifications. This information is intended to assist state DOTs in incorporating IC as a quality control tool for both soils and HMA applications.

Some states have told FHWA that they are planning to try IC for QC purposes on a small number of projects in 2012. Some of the findings of the ICPF study were presented at 2012 TRB in a paper called “Improving QC of HMA Paving using IC Technology.” Going forward, it is anticipated that more research and implementation activities will be conducted by FHWA and state DOTs to encourage the continued study and use of IC on pavement materials construction projects.

Since most major roller manufacturers that market in the U.S. are developing IC technology, it is likely that IC will play a major role in the future.

More info on IC…