The soil compactor is essential equipment for preparing subgrades, bases and fills in construction and infrastructure. Its performance directly affects soil bearing capacity, settlement control and structural durability.
1. Compaction Principles
Compaction is the reduction of soil void ratio through application of mechanical energy. The aim is to increase dry density and improve properties such as:
- Bearing capacity;
- Shear resistance;
- Reduced permeability;
- Control of future deformations.
Compaction performance depends on optimum moisture content, determined by Proctor test (Standard or Modified).
2. Types of Compactors
- Rammer (jumping jack): for cohesive soils and confined areas. Operates by vertical impact.
- Vibratory plate: ideal for granular soils and interlocking pavement.
- Smooth drum roller: for large areas and extended layers.
- Sheepsfoot roller: for clayey soils, promoting deep kneading.
3. Compaction Energy
Efficiency depends on energy applied per unit area. In a rammer, for example, energy is a function of:
- Equipment weight;
- Jump height;
- Impact frequency (blows per minute);
- Foot area.
Typical equipment operates with impact force between 10 and 20 kN.
4. Quality Control
After compaction, verify:
- In-situ density (sand cone or nuclear gauge);
- Degree of compaction (% of Proctor);
- Moisture content;
- Compacted layer thickness.
For structural works, compaction degree is usually required to be ≥ 95% Standard Proctor or ≥ 100% Modified Proctor, per project specification.
5. Operational Best Practices
- Compact in layers with controlled thickness (15–25 cm);
- Control moisture before application;
- Use overlapping passes;
- Avoid over-compaction that causes pumping.
Technical Conclusion
Compactor selection should consider soil type, project volume, area confinement and structural requirement. Inadequate compaction leads to differential settlement, pavement cracking and loss of structural performance.
