If you’re having any kind of groundworks construction, it’s important that you discuss it with a qualified piling contractor so that you understand which piling method will work best. This can depend on a variety of factors including space, soil conditions and noise. Here, we’re going to take an in-depth look at one of the most popular piling methods known as CFA piling.
What does CFA Piling stand for?
CFA stands for Continuous Flight Auger Piling, and because it is almost vibration free it is one of the quietest forms of piling. This makes it ideal for environmentally sensitive areas. It is suited to a range of ground strata including:
- Clay and soft rocks
CFA piles are also known as auger cast piles, screw piles and augered cast-in-place piles (ACIP). It is a non-displacement system, meaning that the soil excavated from the pile is brought to the surface. CFA piles were developed in the USA in the 1940s, were first used in the UK in the 1960s and were introduced to Europe in the 1970s with the invention of the first hydraulic piling rigs.
Continuous Flight Auger piling is a cast in-situ process and piles are constructed using a hollow stem continuous flight auger. This auger drills to the required depth in order for high-quality concrete to then be pumped through the hollow stem.
While the concrete is poured the auger is extracted in a rotating motion so as to remove the ground material. When the concrete extends to ground level, a steel reinforcement cage is then plunged into the wet concrete.
As technology advances, piling rigs get more sophisticated. CFA piling rigs are now often equipped with computer displays that show the drilling and concreting parameters, as well as the speed of rotation and penetration during the drilling phase. This helps to monitor, control and record the installation process.
What are the advantages of CFA piles?
This type of piling system has a lot of benefits, including:
- This type of piling method is free from significant vibration and noise so it has low levels of disruption.
- The installation is quick compared to other piling methods.
- When used on a large scale it can be very economical.
- They can be used for a range of challenging ground conditions.
- They have depths of beyond 35m and diameters ranging from 450mm to 1200mm.
Are there any disadvantages of CFA piles?
Although there are a lot of benefits to using CFA piles, there are a few circumstances in which they would be less likely to be used. Some disadvantages of CFA piles include:
- If you’re using them on a small scale they aren’t very economical
- They are not recommended for alternating hard and soft ground layers or changing strata.
- There is a limited capacity for bending moments or lateral and tension forces
When are CFA piles used?
CFA piles can be made as single piles or as part of a pile group (similar to driven foundations). They are commonly used for multi-story building, large structural foundations and bridges.
Dart & Co Piling Contractors
If you’re looking for a piling contractor, give us a call. We are equipped to assess, design and install various types of piling foundations for a range of building types. If you’d like to talk to a member of our team about what to do next, give us a call on 08002061563 or fill out our contact form to request a response.