Next, let’s discuss how beginners can operate a vibratory roller.

【文章概要】A vibratory roller, also known as a soil compactor, is a commonly seen piece of road‑construction machinery. Its operating principle typically relies on its own dynamic force to compact and improve the plasticity of sandy soils, semi‑clayey soils, or asphalt concrete pavements.

Vibratory roller Also known as a soil compactor, it is a commonly seen piece of road‑construction machinery. Its operating principle typically relies on its own weight and impact force to compact sandy, semi‑clayey soils or asphalt concrete pavements, thereby enhancing their plasticity and density.

I. Standards for Vibratory Rollers

1. When compacting the ground, proceed gradually from the edges of the pavement, rolling progressively toward the center. The compacted zones resulting from two passes—front-to-back and side-to-side—should overlap by a specified width. For tandem rollers and single-drum vibratory rollers, the overlap width should be 250–300 mm; for static three‑drum rollers, the overlap width may equal half the width of the main roller.

2. The vibratory roller should be positioned as close as possible to the asphalt paver during compaction, and a staged compaction sequence—starting with light passes and gradually increasing pressure—should be adopted to ensure that the required degree of compaction is achieved before the asphalt mixture cools to a temperature below the specified minimum ambient temperature.

3. During compaction, pay close attention to the ambient temperature. For modified asphalt, the optimal temperature range is 80–150°C (for base‑oil‑based bitumen, 90–110°C). If the compaction temperature is too high, the material will be squeezed ahead of the rollers, leading to edge bulging that causes transverse cracking and adhesion to the rollers. Conversely, if the compaction temperature is too low, the bitumen’s viscosity increases, making it difficult to achieve proper compaction, and the finished pavement may exhibit cracking.

4. When compacting Mui Wo asphalt concrete, operators should first drive the drive wheels into the freshly laid mix to minimize wave‑like ripples and cracking. Maintain a steady rolling speed, and avoid stopping the roller on the hot surface layer; decelerate or start up gradually to reduce compaction marks.

II. Techniques for Operating Vibratory Rollers

1. Along the route, compaction shall be carried out in the vertical direction, following the principle of “light first, then heavy; slow first, then fast; edges first, then center (for curved sections, proceed from the inner side to both outer sides).” The compaction sequence shall be: one pass under negative pressure, followed by 3–4 passes with strong vibration, 2 passes with weak vibration, and another pass under negative pressure, maintaining a travel speed of no more than 4 km/h.

2. When rolling uphill, the roller must maintain a steady speed during acceleration, deceleration, and speed changes to prevent the rate from becoming too high or too low.

3. Before performing compaction during uphill starts, the asphalt mixture should be cooled to the specified upper limit of ambient temperature, followed by pre‑compaction of the base course. Vibration compaction may only be applied once the asphalt mixture’s temperature has dropped to the lower limit (120°C).

4. When driving downhill, abrupt changes in speed and braking should be avoided as much as possible.

5. When compacting a downhill slope with a steep grade, first use a light‑weight roller for preliminary compaction, then follow up with an extra‑heavy‑weight roller or a vibratory roller to achieve thorough compaction.

6. Whether starting on an uphill grade or descending a slope, the lower layer of asphalt concrete must be clean and dry, and a tack coat of asphalt binder must be applied to prevent the asphalt mixture from shifting during compaction.

7. Whether starting on an uphill grade or compacting on a downhill slope, the vibratory roller’s drive wheels should always be positioned at the rear. This arrangement offers the following advantages: during uphill starts, the rear drive wheels can withstand both the incline and the forward thrust generated by the machine itself, while the front tires perform initial compaction of the surface, thereby bearing the substantial shear stresses imposed by the drive wheels. On downhill grades, the impact forces resulting from the roller’s own weight are counteracted by the brakes on the drive wheels; only after the front tires have rolled over the asphalt mixture does the pavement provide sufficient support to enable the rear drive wheels to resist shear stresses.