Better Roads

Better Roads June 2014 5 Photo courtesy of Caterpillar Paving Products • Optimized labor deployment and construction time. Contractors can roll the right amount of material with the right amount of compactive effort on each pass to ensure long-term performance. • Reduced compaction costs and maintenance require- ments. The flexibility to make fewer passes to achieve the correct compaction level minimizes fuel use and equip- ment wear and tear. • Ability to make midcourse corrections. Adjusting dur- ing compaction of one layer before additional layers are put over it ensures subsurface problems do not affect the entire road surface, and • Ability to maintain construction records. Data from the IC, along with GPS or differential global navigation system satellite (DGNSS) coordinates of compaction activity, can be downloaded into construction quality databases and stored for future reference. For both single-drum soil compaction, and double-drum asphalt compaction, intelligent compaction usually is acceler- ometer-based, with the gauge located on the roller frame. For each manufacturer's system, FHWA requires the fol- lowing: • An intelligent compac- tion measurement value (ICMV), • A GPS-based documentation system, • An onboard color-coded display, • A surface temperature measurement system for asphalt rollers only, and • Raw data that are Veda-compatible. Veda 2.1 is a map-based tool for viewing and analyzing geo- spatial data, and is the software around which all IC activity revolves. Veda can import data from various intelligent com- paction equipment to perform editing, data layering, point testing and analysis; Veda displays compaction information in easy-to-read formats, including graphs and maps. Veda's functionality includes viewing and analyzing IC and other related geospatial data. You can overlay the data onto a map of the site, perform various statistical analyses and create reports. IC data flow consists of data collection, data transfer and data processing. Now, data analysis options have been en- hanced with a new Veda export function, which exports recorded data in a standardized format required today for documentation purposes on many construction sites in North America. Read more about Veda or download the program at intelligentcompaction.com. Correlating measurement values To date, manufacturers have been unable to relate the mea- surement of buildup of stiffness beneath a drum to an actual density value; instead they use their own measurement values for stiffness and are trying correlate stiffness data acquired during intelligent compaction activity with nationally ac- cepted density specifications. For example, today Bomag calls its stiffness measurement value Evib; Caterpillar/Trimble, the CMV; Hamm/Wirtgen, the HMV; and Sakai, the CCV. This inability to directly relate stiffness measurement values from the accelerometer or other process to actual engi- neering values stands in the way to use of IC for soil com- paction for quality assurance or acceptance. "Consistently reliable cor- relation between intelligent compaction measurement val- ues and in situ density readings have not been established," says FHWA's Michael Arasteh, Office of Technical Services, Baltimore, at a workshop in January 2014. "On many projects, there has been a 'relationship' between ICMV and density," he adds, but the firm, reliable link is not yet there. However, IC can be used as a quality control tool, Arasteh says, adding "Contractors can use IC capabilities to improve their compaction process." IC techniques [usually] use accelerometers mounted on the frame of the roller to gather and analyze the vibrations of the roller during compaction, write Manik Barman, Moeen Nazari, Syed Asif Imran, Sesh Commuri and Musharraf Zaman, College of Engineering, University of Oklahoma-Norman; Fares Beainy, Volvo Construction Equipment, Shippensburg, Pennyslvania; and Dharamveer Singh, Indian Institute of Tech- nology Mumbai, in their 2014 Transportation Research Board (TRB) paper, Application of Intelligent Compaction Technique in Real Time Evaluation of Compaction Level during the Construction of Subgrade. IC systems can collect and analyze the roller vibrations to On the Cat Compaction Control display in-cab, operators often configure green color to indicate areas where the target is met and red color to indicate areas that do not meet the target. RoadScience_BR0614.indd 5 6/2/14 1:13 PM

• Cover
• ROAD SCIENCE: Down to the Dirt: Intelligent and new technologies are revolutionizing soil compaction. Better Roads takes a look at new technologies of soil compaction, covering high performance vibration via variable drum frequencies, high and low amplitu
• APPLICATIONS & INNOVATIONS: Minnesota's New Solutions for Aging Pavement: Using myraid concrete pavement restoration techniques, this state DOT minimized cost and traffic disruption while maximizing longevity and optimizing results.
• New Road Products
• Advertiser Index
• Marketplace
• HIGHWAY CONTRACTOR: Fighting Thermal Segregation: A temperature bar can provide a thermal profile in real time to protect against inconsistent densities that can occur if freshly paved asphalt pavement becomes too cool and does not compact properly.
• Transportation Talk: Better Roads Editor-at-Large Tina Grady Barbaccia talks with the U.S. Transportation Secretary Anthony Foxx.
• In Court: No License Doesn't Mean No Payment: Unlicensed contractors on federal construction projects are entitled to payment under the Miller Act.
• The Last Word: Material Handler Tries to Destroy B15 Smartphone: The phone is dropped from 35 feet, plunged in water and more, but can it pass the "Tina Test?" Web Extra Video