The core compaction principle of road rollers is to reduce the gaps between particles of compacted materials (such as soil, gravel, and asphalt mixture) through the application of external force, making them arrange more closely, thereby improving the compactness, strength, and stability of the materials. There are significant differences in the compaction mechanisms of different types of road rollers. The core difference lies in the form and transmission mode of external force, which are detailed as follows:

Static Road Rollers: Gravity Static Pressure Mechanism

Compaction Mechanism: It relies entirely on the overall weight of the machine itself to exert a constant static pressure on the compacted materials. Compaction is achieved through the gravitational extrusion, displacement, and rearrangement of material particles.

Functional Characteristics: The acting force is stable and impact-free, the compaction process is slow, the compaction depth is relatively shallow, and it mainly acts on the surface layer of the materials.

Key Difference: No additional power is used to assist compaction; it only relies on weight-based pressure application. It is suitable for working conditions sensitive to impact, avoiding material structure damage caused by vibration or impact.

Vibratory Road Rollers: High-frequency Vibration Excitation Mechanism

Compaction Mechanism: On the basis of its own gravity, the eccentric block inside the vibrating wheel rotates at high speed to generate high-frequency, alternating excitation force, forcing the particles of the compacted material to vibrate violently. The friction force of particles in the vibrating state is greatly reduced, and they will quickly fill the gaps to form a dense structure.

Functional Characteristics: High compaction efficiency and deep compaction depth (up to tens of centimeters below the surface layer). The excitation force and vibration frequency can be adjusted according to the material type, which is suitable for the compaction needs of most subgrades and base courses.

Key Difference: It adopts the dual acting force of gravity + vibration, which is the most widely used compaction technology at present. It is essentially different from the single gravity pressure application of static road rollers.

Impact Road Rollers: Falling Impact Compaction Mechanism

Compaction Mechanism: A tractor drives the triangular impact wheel to roll. During rolling, the impact wheel will periodically lift and fall, and use its own weight and falling kinetic energy to generate concentrated impact load on the ground. This impact force will propagate deep underground in the form of waves to achieve compaction of deep soil.

Functional Characteristics: Large compaction energy and extremely deep compaction depth (up to 1–5 meters), far exceeding that of static and vibratory road rollers; however, the operation speed is slow, and the effect on improving surface flatness is limited.

Key Difference: The acting force is periodic impact load, rather than continuous pressure or high-frequency vibration. It is specially designed for the deep compaction needs of high-fill subgrades, and its compaction mechanism is completely different from that of the previous two types of road rollers.

Pneumatic-tired Rollers: Kneading and Extruding Compaction Mechanism

Compaction Mechanism: It relies on the weight of multiple sets of inflatable rubber tires to apply pressure. Meanwhile, during driving, the tires will produce slight elastic deformation due to the reaction force of materials, forming the dual effects of kneading and extruding on the compacted materials. This effect can make material particles interlock with each other and avoid wheel marks caused by steel wheel rolling.

Functional Characteristics: The compaction process is gentle, the surface flatness after compaction is high, and it will not damage the surface structure of materials.

Key Difference: It adopts the combined effect of pressure + kneading, which is different from the rigid pressure application of steel wheel rollers, making it more suitable for the final compaction of asphalt pavements.