Blog | Safe Mechanical Pile Breaking
Concrete piled foundations are essentially columns of concrete available in a variety of different geometrical prismatic shapes; most commonly square, rectangular, circular or octagonal. They incorporate one or more reinforced steel bars (rebars) that run longitudinally within the concrete providing stability and strength. Pre-cast concrete piles are cost effective as they are mass produced in large batches and provide an excellent solution where soil conditions are poor and deeply driven piles are necessary for adequate support. They are ideally suited to being driven under water because of high resistance of the concrete to the effects of chemical and biological deterioration, especially when compared to using timber or steel piles.
In most cases, concrete piles will need cropping to a form a consistent and uniform height for the fitting of pile caps or capping beams. It is preferable to cast the piles higher than the eventual finish level so any impurities or damage towards the top of the pile will be removed during the cropping process. Consideration should also be given to whether the final height requires a protrusion of the rebar for subsequent construction, or whether a flat crop of both the concrete and rebar is required.
The traditional method of using pneumatic jack hammers to reduce concrete piles raises a number of health and safety concerns. The HSE increasingly recommends the use of hydraulically operated methods such as pile croppers and similar mechanical solutions. Apart from the reduction of possible exposure to hand-arm vibration syndrome (HAVS), there are a number of major advantages when using mechanical over non-mechanical methods of pile cropping; listed below are just some of the benefits:
- Excavator control means operatives can keep safely clear of the immediate cropping area;
- There are considerable time savings – taking as little 3 minutes per pile compared with up to 45 mins when using traditional pneumatic rock drills or hammers;
- Mechanical croppers can both ‘rough cut’, then ‘clean nibble’ to the required height;
- Depending on the application, certain models of cropper can also cut the rebar, eradicating the need for hand held angle grinders etc;
- Using mechanical croppers greatly reduces the risk of causing unwanted damage to the steel rebar.
Hydraulic cropping equipment has been developed to suit most pile cropping scenarios and the type used largely depends upon individual projects and designs. Pile Croppers and Multi-Bar Croppers are available for square sections with single and multiple rebars. For rapid height reduction plus final nibbling, Power Croppers would be the ideal choice, whereas for large circular piles ranging from 1200mm – 1800mm diameter, a CFA Cropper or 4 Jaw Cropper is a fast, safe method of reducing height for in-situ concrete piles.