What is a CFG Pile?
CFG pile stands for Cement Fly-ash Gravel pile, a composite foundation pile made of crushed stone, stone chips, sand, fly ash, cement, and water. As a low-strength concrete pile, it effectively transfers loads to deeper soil layers while working in conjunction with the surrounding soil to enhance bearing capacity. CFG piles offer excellent technical performance and cost efficiency in ground improvement projects.
Key Construction Steps
1. Drilling Process
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When encountering hard soil layers, reduce drilling speed if the drill rod shakes or penetration becomes difficult.
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The site technician must investigate and report to the chief engineer for further instructions.
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Pile length must be determined based on design requirements, geological conditions, and drilling current changes.
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Ensure the pile penetrates soft soil layers and enters the bearing stratum by at least 1.0m.
2. Pumping Concrete Mixture
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Before pouring, check the slump and workability of the concrete and record the results.
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Transported concrete must not segregate before reaching the pouring point.
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Before initial pouring, flush the conduit with cement mortar (same mix ratio but without aggregates).
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Control the pumping speed initially and monitor the lifting speed of the drill.
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Lifting speed must be synchronized with concrete pumping to avoid voids.
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Maintain the drill head submerged in the concrete surface, with an optimal lifting speed of 2m/min–3m/min.
3. Pile Head Trimming
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After 24 hours, remove excess soil using small machinery and manual labor.
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Keep machinery 20cm away from the pile edge to prevent damage.
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Reserve 20cm of soil for manual leveling.
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For pile cutting, use three steel chisels placed 120° apart to split the pile head radially.
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Smooth the pile head with a small chisel.
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If cracks occur during trimming, follow concrete pile repair protocols: roughen the surface, apply cement slurry, and refill with higher-grade concrete before compaction.
4. Pile Cap Construction
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Proceed only after approval from the supervisor.
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Install formwork according to the designed pile cap dimensions.
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The pile cap is cast-in-place with the CFG pile, and the upper 4m of the pile is reinforced.
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Main reinforcement bars must extend into the pile cap and be welded to the top reinforcement.
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Follow design specifications for rebar binding, concrete pouring, and curing.
Why Choose CFG Piles?
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Cost-effective compared to traditional deep foundation solutions.
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Enhanced load-bearing capacity through composite soil-pile interaction.
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Adaptable to various soil conditions.
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Minimal environmental impact due to the use of fly ash (a byproduct of coal combustion).
For professional CFG pile installation and foundation solutions, consult experienced geotechnical contractors to ensure compliance with engineering standards.
