Demolition of Old Runways: For existing asphalt, plastic, or concrete runways, the mini excavator's breaker hammer is first used to break the old surface layer, followed by excavation of the base soil.
New Foundation Excavation: Excavate the runway base (such as gravel layer, lime-soil cushion) according to design drawings, with a typical depth of 30-50 cm, while ensuring drainage slopes (generally 1%-2%).
Adaptability to Special Environments: School playgrounds are often surrounded by teaching buildings, green belts, and other facilities. Mini excavators (with a body width ≤2.5 meters) can operate in narrow spaces, reducing damage to surrounding facilities.
In a plastic runway renovation project of a middle school, a 1.5-ton class mini excavator was used with a breaker hammer to break a 15 cm thick old concrete runway, completing 200 m² of excavation work per day. This is 8 times more efficient than manual construction, and the verticality error of the foundation pit slope is <3 cm.
Overall Leveling: Level the entire playground soil to the design elevation, with an error controlled within ±3 cm, providing a uniform support for the subsequent base layer laying (such as gravel, cement-stabilized layer).
Slope Control: The entire playground should form a slope inclined toward the drainage ditch (generally 0.5%-1%), and the runway area should smoothly connect with areas like football fields and basketball courts.
Earthwork Allocation
Fill Area Treatment: If there are low-lying areas on the site, first use the excavator bucket to transport the excavated soil to the fill area, backfill in layers (each layer thickness ≤30 cm), and cooperate with a roller for compaction.
Excavation Area Fine Leveling: For areas higher than the design elevation, use the bucket to scrape off excess soil. When operating, drive at a low and constant speed, keep the bucket bottom parallel to the ground (angle of about 5°-10°), and avoid wavy undulations.
Elevation Control
Adopt the "grid method" for measurement: Divide the site into 5m×5m grids, set elevation stakes at the center of each grid, and the excavator operator adjusts the bucket height according to the stake marks for gradual leveling.
Fine Leveling
In the final leveling pass, replace with a narrow bucket (width ≤1.2 meters), operate back and forth at a speed of 1-2 km/h to eliminate local unevenness, and supplement with manual raking if necessary.
Cooperate mini excavators with vibratory rollers (tonnage ≤2 tons): After the excavator levels the site, the roller compacts 3-4 times according to the principle of "first light, then heavy; first slow, then fast," so that the soil compaction degree reaches more than 90% and avoids later settlement.
Operators must work with valid certificates. Conduct site surveys before construction to avoid underground pipelines (such as cables, water pipes), and mark them with a ground-penetrating radar in advance.
Set warning signs around the playground to prohibit non-construction personnel from entering, and equip sufficient lighting for night operations.
Earthwork transport vehicles must be covered with tarpaulins to avoid dust; excavators are equipped with dust covers, and water is sprayed for dust suppression during breaking operations.
Control operation time (e.g., 8:00 AM - 6:00 PM) to reduce noise impact on teaching areas, and set up sound barriers if necessary.
| Equipment Type | Tonnage Range | Operational Efficiency | Applicable Scenarios |
|---|
| Micro excavator | 1-3 tons | 50-100 m²/day | Narrow areas (such as inner corners of runways) |
| Small crawler excavator | 5-8 tons | 150-250 m²/day | Conventional runway foundation excavation and large-area leveling |
| Wheeled mini excavator | 3-5 tons | 100-180 m²/day | Travel on hardened ground, suitable for short-distance relocation |
Summary of Advantages: Compared with large equipment, mini excavators have lower fuel consumption (saving 30% fuel), lower rental costs (daily rent about 800-1500 RMB), and do not require large transport vehicles for relocation, making them suitable for renovation projects of school playgrounds with "short construction periods and small sites."
Through the precise operations of mini excavators, school playground renovation projects can achieve the goals of "efficient construction, quality control, and environmental safety," laying a solid foundation for subsequent runway paving and site hardening.
