Piles in situ

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CPI-5 piles

Piles which are drilled and concreted in situ, and in which permanent casing is used to support the walls being drilled, and is introduced together with the pile reinforcement.


Excavation in soft and medium ground is completed using short propeller drills. In cases with harder ground, a tungsten carbide tipped drill is needed. In very hard, rocky ground a circular tungsten carbide tipped crown drill is used.

In CPI-5 micropiles casing is put into the walls of the excavation and remains there permanently. This is known as permanent casing.

Once the desired depth is reached, the bottom of the excavation is cleaned using a scoop (‘bucket´).

Alter clearing the base a steel reinforcement is introduced with the help of additional equipment (a crane). To guarantee the minimum necessary coverage it is raised 20cm above the base of the excavation and separators are used for correct centring.

After placing the reinforcement the concreting begins. To pour the concrete into the hole properly, avoiding segregation or bleeding, a tremie tube is used. The tube is fed through the steel frame until the base of the hole is reached. Then the concrete is pumped, which should be of a fluid consistency. This being denser than the support fluid (bentonite slurry of polymer) which stays at the base, pushing the concrete to the surface.

Whilst the concreting progresses, the tremie tube is simultaneously raised, taking care to always keep it two metres below the level of the fresh concrete. Once the concrete reaches ground level, the concreting ends.