by Jon M. Casey
Just when you think you’ve seen the latest in paving compaction technology, another brilliant innovation comes to the forefront of what’s available in pavement compaction technology. At the recent World of Asphalt-2015 in Baltimore, MD, Dr. Fares Beainy of Volvo Construction Equipment, took a few minutes to explain how the new Density Direct addition to Volvo’s Intelligent Compaction gives operators additional information to help reduce the need for core sampling and improved productivity and quality of pavement compacting. System components include the display, an accelerometer, front and rear infrared mat temperature sensors, GPS, a base station and an optional GPS Rover.
Dr. Beainy said the Volvo Intelligent Compaction (Volvo IC) feature is different from other systems available in that Volvo IC with Density Direct provides real-time density values while others give Compaction Measurement Values (CMV). These CMV values are based on material stiffness. Beainy noted that stiffness measurements are not universally accepted and that relative density is understood and accepted in all compaction projects.
He pointed out that other manufacturers offer intelligent compaction systems that provide pass mapping and temperature mapping information. These suppliers include Bomag, Caterpillar, Dynapac, Hamm, Sakai and Ammann/Case. Third party equipment suppliers include Topcon, MOBA and Trimble. None however offers real-time density information like Volvo’s Density Direct.
Volvo IC provides asphalt compactor operators with Pass Mapping and Temperature Mapping. With the addition of Density Direct, the Volvo IC system also displays Density Mapping, information that is provided for the operator on an 8” x 10” digital display system mounted in the cab of the compactor. He said Pass Mapping is the same as pass counting. This function shows how many times the asphalt compactor has rolled over a certain area of the mat. Each pass is given a different color so the operator can see which passes have been made. It shows drum overlap as well. In this way, the operator is able to make the passes that he needs to in order to achieve uniform coverage and mat compaction.
Temperature mapping, also a function of Volvo IC, provides real-time mat temperatures ahead of the compactor. It displays a temperature map that shows the path of the roller overlaid with the last temperature recorded. Together, the operator can use this information to do an optimum job.
Beainy said Density Direct values are communicated to the operator on the digital screen that displays a colored density map that depicts each roller pass and they are calculated density amounts shown in different colors. The grid on the map is depicted in 1-foot squares and the density for each square foot is reflected in a color-coded value that is also displayed numerically on the right side of the screen (see demo photo).
“Once the compactor is calibrated at the start of the day’s job to the work that will be done that day, Density Direct will produce density calculations that are accurate to 1.5 percent of core sampling,” he said. “This calibration is stored for each lift. As the operator makes a rolling pass on the mat, the density compaction results are shown on the digital display.” He said the “lift” information could be stored for more than one job so that an operator can do different thicknesses of paving mats, so that he can return to an earlier jobsite and finish a paving job that was started earlier.
Dr. Beainy said that this new technology will be available on Volvo vibratory compactors in the fall of 2015. Initially, Volvo IC and Volvo IC with Density Direct will be available on the DD110B, DD 120B and the DD140B in North America. It will be sold, installed and supported by the Volvo Construction Dealer Network. He added that it is possible that this technology would be available as an aftermarket installation in the future, but initially it will only appear on new Volvo units. For more information visit www.volvoce.com/densitydirect
by Jon M. Casey