Defining IC

Intelligent Compaction (IC) technology simplifies the achievement of proper compaction. IC utilizes vibratory drums equipped with a measurement and control system. This automatically controls compaction by monitoring and responding to measurements during the compaction of soil or asphalt. A computer to record and document roller passes and stiffness readings, plus a global positioning system such as GPS are required. Intelligent Compaction adjusts amplitude and frequency automatically in response to the stiffness feedback from the vibrating drum – without operator intervention. An IC system can collect and analyze data and then make a decision to modify compaction at the rate of 1,700 to 2,400 times per minute.

Evaluating compaction
To confirm that proper compaction has been achieved, the standard method of testing was for density or the absence of air. New terms are now being used when evaluating compaction. Sometimes used interchangeably with stiffness, a different criterion for compaction is modulus: the measure of elasticity or resistance.

Unique factors affect modulus, not just the absence of air. Soil and asphalt characteristics can change in a matter of feet. The changes to modulus during compaction are highly non-linear or inconsistent because variables cannot be exactly predicted. 
Compaction has traditionally been calculated by comparing measurements of random samples against target density values. A standard piece of equipment used to test density in the field is a nuclear gauge. Intelligent Compaction is a more comprehensive field test for modulus that takes into account variables other than just density. Continuous readings also increase accuracy, resulting in more consistent compaction.

Different compaction formulas
Different manufacturers engage various technologies and compaction formulas. The effects of compactor speed, vibration direction, amplitudes and frequency are determined in dissimilar fashions. Precision and repeatability of these compaction values should be verified against standard tests. But, like apples and oranges, the results cannot be compared across the board.

Bomag’s compaction management system (BCM) measures stiffness based the relationship between the surface contact force and the deflection of the roller drum.  Compaction Meter Value (CMV) was pioneered by Geodynamik and is used by Dynapac, Caterpillar and HAMM. This technology monitors stiffness by measuring G-force at the drum’s predictable frequencies.

Compaction Control Value (CCV) is the index used by Sakai. As the stiffness under a vibrating drum increases, the centrifugal force is deflected or returned and becomes more random as the surface is compacted. CCV calculates this relationship in non-linear equations based on levels of compaction. Sakai has been perfecting CCV technology since the late 1980s.

“It’s not always a good thing to be the first one on the block to market a new technology,” says Dave Brown, vice-president of sales and marketing for Sakai America. “Sakai always prefers to do the homework first to ensure that added technology actually benefits customers. Intelligent Compaction is no exception.”

Accuracy on the job
An example of how this new technology can aid contractors. Contractors performing asphalt jobs for highways and road work where they are laying tons of asphalt over both aggregate base and rubbilized concrete are required to adhere to regulations that dictate a required density for aggregate courses used in pavement construction. In this situation the ability to measure density correctly is critical. Machines such as Sakai SV510D compactors use Compaction Control Value that is correlated closely with nuclear gauge density readings of the sub-base. This technology allows an entire paving operation to operate more efficiently, keeping densities more uniform and minimizing inspections. Intelligent Compaction is being proven to be an important improvement to an existing method of work.  In the U.S., the Federal Highway Administration (FHWA), U.S. Department of Trans-portation (DOT) and Transportation Research Board (TRB) all have initiatives to promote IC technology with the same objectives: to automate the compaction process, eliminate over- or under-compaction, and reduce risk by obtaining continuous real-time assessment of job quality during construction work.

Intelligent Compaction is literally ground-breaking technology. Top down, quality can be specified and designed into roads. Bottom up, contractors can exercise quality control in ways never thought possible. Risk factors can be eliminated before they occur. Although buying into IC initially requires making changes and purchasing equipment, Intelligent Compaction delivers a positive return on all investments.

Article courtesy of Sakai America.