Pile Demolition
The breaking down of concrete piles is an essential part of the construction process and a subject that is often not given sufficient early thought in the planning of the work. The adoption of a suitable pile breaking method can result in financial and programmable savings and most importantly will address and reduce potential health and safety issues in relation to this phase of work.
i) Elliott Method
This technique was developed and patented by Jim Elliott of Cornwall and achieved the Quality in Construction Award 1999 through innovation. Chiplime have been using this method since being established and are highly recommended for their advice and best methods of using the system. We have established a partnering relationship with Jim Elliott & Co and have become a nominated subcontractor for carrying out these specialist works.
This revolutionary method allows for the removal of surplus concrete above the required cut of level simply by drilling, splitting and then lifting. It works on all diameter piles ranging from 300mm – 3000mm.
Isolation foam is fixed to the steel cages before being installed. On excavating the piles/walls are ready for breakdown. The only work required is a single hole, usually 48mm diameter, to be drilled at the cut off level unless plastic tubes are inserted which will need to be located. The hydraulic splitter is then inserted and activated where upon the surplus is severed from the body and then lifted by an excavator or crane. Lifting is usually carried out by using lifting pins, these will require additional holes to be drilled, or by lifting handles which are inserted into the wet concrete on casting.
This method works on all types of concrete foundations, CFA piles, diaphragm walls and barrettes etc and on all configuration of piles including secant or contiguous piled walls.
For the success of this method the isolation foam must be fixed securely from the top to the agreed level and all cages must be placed within agreed tolerances. However, minimal head preparation may still be required to achieve the accurate finished cut off level by saw cutting and hand trimming.
ii ) Cropping
Pile crunching is a method used by employing hydraulic pile breakers attached to excavators. Over the years Chiplime have invested in a number Taets pile breakers. These pile breakers are very advanced, efficient and time saving systems for trimming concrete foundation piles. This process results in a good horizontal finish, undamaged reinforcement and no cracks below the cut off level.
However, minimal head preparation may still be required to achieve the accurate finished cut off level by saw cutting and hand trimming.
Prefabricated piles:
Chiplime most commonly use Taets type 3 pile breakers for prefabricated piles. These are fixed frame 4 cylinder pile cutters suitable normally for square and round piles and for specific pile ranges usually up to 350mm . Often providing the only solution to pile cutting where access is restricted. With the pile cutter slung by chains from an excavator over the pile, powerful chisels exert even pressure causing the pile top to break leaving the cut–down pile ready for future foundation work.
Continuous Flight Auger (C.F.A) Piles:
The pile breakers for C.F.A piles, or often referred to as cast or in-situ piles, are highly modular systems that are easy to adjust to each pile diameter. The breaking process is many times faster than the conventional breaking methods and is fully controlled throughout its operation.
To adjust the pile breakers accurately to the varying pile features, half links can be added and removed because they are without hydraulic cylinders.
The type 314 is suitable for pile diameters from 300mm to 1000mm and type 380 for pile diameters from 700mm to 1800mm.
iii) Conventional
The mechanical method can be used on all configuration of piles, simply by excavator mounted hydraulic breakers. Piles are broken down to a certain level above the cut off point and then trimmed by hand using pneumatic breakers.
Secondly piles can be hand broken, however, this system is very labour intensive and is more effective in restrictive areas when no other means are applicable. However, this method carries a high risk of hand arm vibration syndrome (HAVS) caused by regular exposure to vibration. Chiplime are aware of their duties under the Health & Safety act 1974 specifically HSE publication HS(G)88 Hand-Arm Vibration 1994. Chiplime have therefore adopted a policy to manage these risks by avoiding the use of such tools in the first instance, however, have implemented a policy of purchasing low vibration tools, reducing exposure times by job rotation and by deploying HAV meter equipment.
