When compacting different materials (asphalt, stabilized soil, sand-gravel), the differences in roller configurations mainly revolve around the physical properties of the materials (such as cohesiveness, particle gradation, temperature sensitivity) and compaction objectives (such as compactness, flatness, and prevention of aggregate crushing). Specific differences are reflected in aspects like roller type, operating parameters, and auxiliary configurations. The detailed comparison is as follows:

I. Core Differences: Comparison Table of Compaction Requirements for Different Materials and Roller Configurations

II. In-depth Analysis of the Reasons for Key Configuration Differences

1. Roller Type Selection: Based on Material "Force Response"

• Asphalt Mixtures: Asphalt is in a "viscoelastic state" at high temperatures, requiring phased compaction:

• Initial compaction: Small-tonnage steel drums with static pressure/weak vibration (to fix the shape and prevent pushing).

• Intermediate compaction: Pneumatic-tired rollers (using the "kneading effect" of tires to squeeze the asphalt film and enhance particle bonding).

• Final compaction: Steel drums with static pressure (to eliminate wheel marks and ensure flatness).
  Padfoot drums are prohibited as they will damage the integrity of the asphalt surface.

• Stabilized Soil: Containing cementitious materials (cement, lime), compaction requires "both densification and cracking prevention":

• Initial compaction: Light steel drums with static pressure (to avoid damaging the newly formed stabilized soil structure).

• Intermediate compaction: Padfoot drums (to enhance the kneading of soil particles, improve deep compactness, and avoid crushing fine particles).

• Final compaction: Static pressure to eliminate surface unevenness.

• Sand-Gravel Materials: No cohesiveness, relying on particle interlocking for load-bearing:

• The flexible contact of pneumatic-tired rollers enables uniform pressure transmission to each particle (steel drums tend to cause local particles to "pop out").

• Intermediate compaction: Vibratory rollers with high excitation force (to allow coarse particles to interlock in a misplaced manner and fine particles to fill voids).

• Final compaction: Pneumatic-tired rollers to further "smooth" particles and avoid local looseness.

2. Operating Parameters: Matching Material "Compaction Sensitivity"

• Temperature (Asphalt Only): The viscosity of asphalt increases sharply as temperature decreases. If the temperature is too low (e.g., <80℃ for final compaction), asphalt hardens, making it impossible to eliminate wheel marks through compaction; if the initial compaction temperature is insufficient (<150℃), it may lead to substandard compactness and rutting in the later stage.

• Moisture Content (Stabilized Soil/Sand-Gravel):

• For stabilized soil: When moisture content is lower than the optimal value, the friction between soil particles is high, making compaction difficult; when higher than the optimal value, it tends to form "rubber soil" (rebounds after compaction, unable to achieve densification).

• For sand-gravel: It needs to be moist (to bond fine particles); otherwise, dust will be generated during compaction, and particles cannot interlock.

• Vibration Parameters (Frequency/Amplitude):

• Stabilized Soil: "High frequency and low amplitude" – High frequency allows fine particles to fill voids quickly, while low amplitude avoids impact damage to the initial structure formed by cementitious materials.

• Sand-Gravel: "Low frequency and high amplitude" – Low-frequency vibration can transmit deeper, and high amplitude enables coarse particles to produce large displacement for interlocking.

• Asphalt (Intermediate Compaction): "Medium-high frequency and medium amplitude" – Balances compactness and surface flatness, avoiding asphalt pushing caused by excessive amplitude.

3. Auxiliary Configurations: Solving "Special Issues" of Materials

• Asphalt Cohesiveness: Requires automatic water spray (to prevent adhesion to rollers), and the water spray must be atomized (excessive water spray will rapidly reduce asphalt temperature, leading to compaction failure).

• Structural Fragility of Stabilized Soil: Uses padfoot drums (to enhance kneading instead of rigid compaction) and prohibits water spray (to avoid moisture content out of control).

• Non-cohesiveness of Sand-Gravel: Uses pneumatic-tired rollers (flexible extrusion to avoid particle displacement) and requires water spray (to enhance fine particle bonding and prevent dust).

III. Common Misunderstandings and Precautions

• Asphalt Compaction: Do not use pneumatic-tired rollers for initial compaction.
  At the initial compaction stage, asphalt has high temperature and strong cohesiveness, so tires tend to adhere to the asphalt mixture, causing surface roughening and reduced flatness. It is necessary to first use double-drum static pressure/weak vibration to fix the shape, then use pneumatic-tired rollers for intermediate compaction.

• Stabilized Soil Compaction: Avoid over-vibration or delayed compaction.
  After cement-stabilized soil initializes (compaction should usually be completed before cement initialization), over-vibration will cause base cracking; excessive amplitude (e.g., >1mm) will crush aggregates and reduce base strength.

• Sand-Gravel Compaction: Avoid compaction in a completely dry state.
  The friction between dry sand-gravel particles is low, and it tends to "slip" during compaction, unable to achieve densification. It is necessary to spray water until the surface is moist (can be held into a ball by hand and scattered when dropped) to realize particle interlocking through vibration.

In conclusion, the core logic of roller configuration is "material properties determine compaction strategy" – Targeting the temperature sensitivity of asphalt, structural fragility of stabilized soil, and non-cohesiveness of sand-gravel, precise matching in terms of type, parameters, and auxiliary configurations is essential to achieve the optimal compaction effect.