(Continuous Flight Augers)

CFA piling utilises a continuous string of hollow augers which are drilled to the designated design depth. Then, as the augers are extracted, concrete is pumped through the augers to prevent soil collapse. Once at ground level the pile spoil and debris is mechanically cleared and a reinforcement cage is placed into the wet concrete.

CFA Piling typically requires the use of larger hydraulic piling rigs, with weights starting at circa 16 tonnes. Our fleet of specialist piling rigs are also fitted with Jean Lutz and NDT pressure systems which monitor and record pile diameters, depths, drill and flow rates. We find that this additional level of information is often useful to appease regulators such as building control.

Rotary Piling is suited for dry and stable cohesive soils such as Clay, Chalk and some Mudstones and SIltstones. Rotating augers are used to form an open bore hole to the designed toe level. Once the required depth has been achieved, a steel reinforcement cage is lowered into the open bore, and the pile is top filled with concrete.

We have a variety of different rigs which are suitable for bored piling.These range from 3 tonne mini rigs required to work internally or for extensions in a client’s back garden, going right up to large 40 tonne rigs suited to larger sites with good access.

Screw Piles / Helical Piles are ideal for restricted access sites where the use of traditional shallow spread foundations are deemed unsuitable. The piles are typically installed using a range of set ups from hand held tools, to digger mounted units. These piles are installed in 1.5-2.0 metre sections and extend to depths of 6.0 to 18 metres. All depending on the site-specific ground conditions and available working space. These piles are capable of supporting safe working loads of up to 175kN.

(Segmental Flight Auger)

SFA is mini grout piling used on smaller tighter sites where the soils are unstable or granular. A string of sectional hollow stem augers are used to drill to the designed pile toe level, then a grout mix is pumped through the hollow stem augers filling the pile as the augers are being extracted.

Once all augers are out of the ground and all loose debris and material have been removed from around the pile head, a steel reinforcement cage is pushed into the wet grout to complete the formation of the SFA pile.

Driven steel cased piling offers advantages over SFA piles, as they are clean and tidy resulting in less mess, while the lightweight casings are very manageable on site. The pile casings come in different diameters to suit the design load requirements.

Driven cased piles are normally used where the underlying soils are soft. An internal drop hammer is used to drive the lightweight casing into the ground and stopped once a solid set is achieved. After the casing is installed the reinforcement is placed into the casing and filled with concrete.

This piling method is not suitable near to vibration sensitive structures of services.

Mini Rotary Auger Bored piles are used on restricted access sites, where the ground conditions are dry and stable (such as London Clay).

Segmental augers are drilled to the designed pile toe level, the augers are then removed and a pile cage and concrete are placed within the resultant pile bore.