Smart Compaction

There was thousands of square feet to walk, hundreds of manufacturers to visit, and many, many new products to see at ConExpo-Con/Agg 2005 last month in Las Vegas. We'll highlight many of these new machines and technologies in the next issue of Asphalt Contractor, but we wanted to take a look at some of the new designs compaction manufacturers were introducing at the show.

Bomag introduced its new BW190AD-4 HF tandem vibratory roller. Completely new from the ground up, the BW190AD-4 HF offers 79-inch-wide drums and a 131-hp Deutz water-cooled diesel engine. The unit delivers 28,800 pounds of centrifugal force in low amplitude/high frequency (3,600 vpm) and 40,950 pounds in high amplitude/low frequency (2,800 vpm). Independent drum vibration control and standard dual amplitudes allows the roller to handle a variety of lift thicknesses and applications ranging from granular bases to Superpave.

To ensure maximum compaction power per pass, the BW190AD-4 HF is available with Bomag's optional Asphalt Manager technology. The Asphalt Manager system automatically measures and controls the compaction performance of the roller, ensuring continuously optimized compaction results. Vital information, including the current effective amplitude, asphalt surface temperature and vibration values for compaction increases, is available to the operator at all times. This technology allows the user to determine the exact number of passes needed to meet density and quality requirements, and it can provide a printed document for your records.

Along similar lines, Ammann America highlighted its ACE System for its vibratory rollers. ACE — or Ammann Compaction Expert — is an electronic measuring and regulating system. The equipment permanently measures the stiffness of the compacted layer material and indicates the value to the operator. Each pass of the machine provides a full reporting of compaction measurements and automatically adjusts the vibration parameters amplitude and frequency. The system also indicates the optimum travel speed of the roller to the operator to guarantee constant impact spacing.

The working principle of ACE is the automatic adjustment of the compaction energy due to the stiffness of the compacted material — the compaction energy is reduced with increasing stiffness of the layer. The result is that areas that have already reached high stiffness values will be compacted with small nominal vibration amplitudes.

The ACE System is installed in the front drum. The vibration mode of the rear drum is automatically regulated in support of the specific mode of the front drum. This assures that the rear drum will not over compact the results that are achieved with the regulated front drum.

The Hamm Compaction Division of Wirtgen America Inc. also introduced some exclusive technology. The Hamm HD O120V asphalt compactor incorporates the company's oscillation technology. The new roller has an operating weight of 26,345 pounds, a drum width of 78 inches, an offset working width of 81.5 inches, and a working speed of 3.9 mph. The rear drum features oscillation compaction with oscillation forces of 46,125 to 62,775 pounds. The front drum features conventional vibration at a top frequency of 3,000 vpm.

Oscillation compaction works by using horizontal shear forces on hot mix asphalt (HMA), rather than by forcing it downwards by an up-and-down motion. Unlike traditional vibratory compactors that achieve compaction by "bouncing" the drum on the ground, Hamm's oscillation technology ensures that the oscillation drum maintains constant contact with the ground for fast, effective compaction.

Stone SFA3500 Silver Fox Plate

Stone Construction Equipment introduces the SFA3500 Silver Fox forward plate designed for asphalt applications. Unit directs 3,500 pounds of eccentric force to the asphalt. Ideal for patching and finishing, the plate features a unique base plate geometry, more centrally-located eccentrics and a larger effective contact surface. Additional features include a synchronized drive system and 13-quart removable water tank. Power is supplied by either Honda, Briggs or Robin engines.