Cement-Fly Ash-Gravel Pile or CFG Pile was developed based on stone column. When the stone column is applied in soft soil conditions, stone column is not reliable due to the confine resistance is relatively low. Cement and Flyash is mixed with gravel to work as binder therefore CFG column is a rigid column. Due to the CFG column is rigid column, this method could be applied in most of soil conditions. After many years development, now in most of CFG pile cases, lean concrete is used as more popular filling material. The lean concrete could be low grade (K50) to middle grade (K300). Some advantage of this improvement method is :
- CFG can be applied in most soil conditions, such as peat soil, soft clay, fat clay, sandy soil, complicated layered soil or hard soil conditions.
- CFG could use a lot of combinations of material, such as cement-fly ash-gravel, cement-lime-gravel, cement-sand (mortar).
- CFG could form a column from low stiffness column (similar to DCM column) until high stiffness column (similar to spun pile) which means the bearing capacity of CFG composite foundation could be designed in quite a big range to fit the project requirement.
- CFG pile construction fast and in some cases will be more cost-saving compare to other piles.