Rollers must adopt differentiated compaction strategies for different road structure layers (subgrade, base, and surface) to ensure bearing capacity, stability, and durability. Below are the specific application methods:

1. Subgrade Compaction (Earthwork/Rock Fill)

Core Objective: Provide uniform and stable support to prevent post-construction settlement.
Recommended Rollers:

• Single-drum vibratory roller (10–26 tons)

• Impact roller (for high-fill areas)

Key Construction Points:

• Layered filling:

• Loose thickness: Clay ≤20 cm, sandy soil ≤30 cm, rock fill ≤50 cm.

• Each layer must achieve compaction density (≥93%).

• Vibration parameters:

• Low frequency, high amplitude (25–30 Hz, 1.8–2.0 mm) for deep compaction.

• Compaction process:

• 1 static pass (stabilization) → 6–8 vibratory passes (3–5 km/h) → 1 final static pass (smoothing).

• Special treatments:

• Moisture control: Optimal water content ±2% (aerate if too wet, sprinkle if too dry).

• Slope compaction: Roll from bottom to top at ≤2 km/h.

Quality Inspection:

• Sand cone test for compaction density, deflection test for acceptance.

2. Base Layer Compaction (Cement-Stabilized Aggregate/Graded Gravel)

Core Objective: Form a high-stiffness transition layer to distribute loads to the subgrade.
Recommended Rollers:

• Single-drum vibratory roller (12–18 tons)

• Pneumatic roller (final kneading compaction)

Key Construction Points:

• Material requirements:

• Cement-stabilized aggregate: 4–6% cement content, compaction within 2 hours of laying.

• Graded gravel: Maximum particle size ≤1/3 of layer thickness.

• Compaction process:

• Initial: 1 static pass (1.5–2 km/h).

• Intermediate: 4–6 vibratory passes (30–35 Hz, 1.2–1.5 mm, 2–3 km/h).

• Final: 2 pneumatic roller passes (eliminate micro-cracks).

• Joint treatment:

• Transverse joints: 20 cm overlap.

• Longitudinal joints: Stagger by ≥1 m.

Quality Inspection:

• Unconfined compressive strength (≥3–5 MPa for cement-stabilized layers), compaction density ≥98%.

3. Surface Layer Compaction (Asphalt Concrete)

Core Objective: Achieve high density, smoothness, and skid resistance.
Recommended Rollers:

• Dual-drum vibratory roller (initial/intermediate compaction)

• Pneumatic roller (final compaction)

Key Construction Points:

• Temperature control:

• Initial compaction: ≥140°C (standard asphalt) or ≥160°C (modified asphalt).

• Final compaction: ≥90°C.

• Three-stage compaction:

• Initial: 1 static pass + 2 vibratory passes (45 Hz, 0.6 mm, 2–3 km/h).

• Intermediate: 3–4 vibratory passes (40–45 Hz, 0.6 mm, 3–4 km/h).

• Final: 2–3 pneumatic roller passes (4–5 km/h, eliminate marks).

• Special requirements:

• No sudden braking/turning to avoid aggregate displacement.

• Hand-operated rollers for curbside compaction.

Quality Inspection:

• Compaction density ≥96% (nuclear density gauge), air voids 3–7%, smoothness ≤3 mm/4 m.

4. Comparison of Roller Usage Across Layers

5. Troubleshooting Common Issues

• Subgrade "springy soil": Aerate or mix with lime to reduce moisture, recompact.

• Base cracking: Control cement content, cover and cure promptly.

• Asphalt bleeding: Reduce water spray during pneumatic rolling.

6. Summary

• Subgrade: Thick layers, low frequency, high amplitude, strict moisture control.

• Base: Vibration + kneading, ensure material uniformity.

• Surface: Precise temperature/speed control, three-stage compaction.

Follow the principles:

• "Light to heavy, slow to fast, edges to center."

• Verify parameters via test sections before full-scale construction!