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Posted August 9, 2022

Applications: Using Pile Croppers

A safer, more efficient means of cropping off concrete piles. 

A quiet revolution is underway in the construction and civil engineering industries. Hydraulic pile croppers are becoming the ‘must-have’ equipment on sites and projects throughout the world.

One of the leading manufacturers of equipment, National Pile Croppers, managing director, Simon Price, explains what exactly a hydraulic pile cropper is and how to get the best from it.

"Precast concrete piles have been and are used for various civil engineering and construction structures, with common applications ranging from small housing developments to major inner-city renovation, construction and infrastructure projects, such as HS2," Price says. "These mass produced piles are customisable length wise and are suitable for a huge range of applications and ground conditions, thereby offering a cost effective precision piling solution once reduced.

"In years gone by, concrete piles were reduced using methods such as hydraulic or diesel hammers and other inaccurate, expensive and emission producing methods. These outdated methods risked damaging the integrity of the piles and gave rise to associated health problems such as HAV (Hand Arm Vibration syndrome) and the very real risks associated with manual work within unstable/subterranean ground conditions. As a result, hydraulic pile breakers were developed to make the task of reducing these piles safer and more efficient.

"The first major steps in producing the pile croppers we know of today began in the 90s, with the development and refinement of the pile cropping technology being undertaken by members of the current National Pile Cropper (NPC) team. This increased the reliability, safety and cost effectiveness of the equipment over a period of over 20 years. New and market leading equipment has been developed for the various types of piles and applications that are found within the global construction industry."

The work undertaken by the industry acknowledged world-leading NPC team led to a set of pile cropping standards being incorporated into the HSE’s (UK health and safety executive) Guide of Current Practice.

The new generation of pile croppers have also been widely advocated by health and safety professionals and engineers alike. As a result hydraulic pile croppers have become essential in making the task of reducing piles much safer and more efficient.

Defining a pile cropper

A pile cropper (also known as a pile cutter or pile breaker) is a very precise hydraulic shear with defined angles of deflection and points of contact ensuring a clean cut of the excess that does not interfere with the efficacy of the remaining pile. There are a breadth of different types and sizes of available, depending on the task at hand.

For example, augured, bearing, contiguous, secant, CFA, trench and helical displacement with croppers are available from National Pile Croppers (and other companies) in varying sizes ranging normally from 300mm to 1,200mm in diameter.

Mounted on a 360-degree excavator via quick release fittings, pile croppers have proved their versatility and effectiveness in all sectors of the construction industry, from housing to commercial, public to private, utilities, road and rail.

When lowered onto the concrete pile, the hydraulic system operates the jaw(s) which allows the pile cropper to cut a de-bonded pile and cause the concrete to break away leaving a horizontal finish as a result. In doing this the chisels penetrate in a precise direction up to the rebar to make the fracture.

On bonded piles, the chisels will penetrate further, and due to the shape of the chisels and the reaction forces of the rebar, the concrete will break in pieces and can easily be lifted off the pile enabling recycling of the cut away concrete.

Using a hydraulic pile cropper Connection between the excavator and the pile cropper is made via quick release fittings on excavators (generally ranging from 6 to 21 tons) to both flow and return being required with pressures ranging from 150bar to 275bar.

The excavator lifts the pile cropper over the pile and addresses the pile cut off level where a complete horizontal fracture is made. The chisels penetrate in a horizontal direction up to the re-bar to make the fracture.

On bonded piles the chisels will then penetrate further and due to the shape of the chisels and the reaction forces of the rebar, the concrete will break in pieces and can easily be lifted off the pile.

When using a pile cropper, it is advised that the piles should be cast higher than the desired finish level. This is to ensure that any impurities or damage at the top of the pile is removed as part of the cropping process.

In addition to this, it’s important to consider whether a protrusion of the rebar (a reinforced steel bar that is contained within the concrete to offer extra stability) is required for the final height in order to allow for construction to take place.

In order to avoid damage to piles during cutting, it’s important to ensure that the right type of cropping equipment is chosen. This is something that is essential for a successful pile cutting project, especially when specific time frames need to be considered (National Pile Croppers for example have a trained and experienced in-house help desk that advises users of how to get the best results).

A common problem often experienced during pile cutting is when fracturing or spalling occurs beneath the surface of the concrete. This is something that is very frustrating and time consuming for construction teams to put right, as well as expensive from a financial point of view. Therefore, damage to piles should be avoided at all costs, which is something that using the correct pile cropper for the job can help to avoid.

Breaching the gap, National Pile Croppers (NPC) was created by a management team to fully refine customer focused pile cropping solutions. In doing this the team have utilised their 100 years+ of amassed cropping industry experience. Their unprecedented knowledge and passion ensure the supply of the correctly identified equipment, in a fully serviced state, suited for site specific applications, on time, and at competitive price levels.

Over the past eight years, the company has created a complete range of in-house designed, manufactured and maintained pile cropping equipment which has revolutionised the pile cropping industry. NPC is now the only fully vertically integrated pile cropper company taking its products from 3D CAD models all the way through manufacture and into operation in the field.

National Pile Croppers has been one of the construction industry's best kept secrets. From its base in the heart of England, the company has gone from strength to strength developing and supplying its own line of patented customer focused pile cropping solutions to a wide span of customers. These range from multinationals working on HS2 and specialist piling companies, to regional contractors and local ground workers. All have benefitted from the close relationships developed with the NPC team that simply focus on providing what customers need when they need it.

Summary advantages of using a hydraulic pile cropper

  • Considerably faster than conventional methods able to crop up to 100 piles per day
  • Very compact dimensions
  • Low cut-off level
  • Easy to operate
  • No noise, no vibrations
  • No cracks below cut level when used with reinforced debonding methods
  • The reinforcement remains fully undamaged and intact
  • Leaves a perfect horizontal concrete fracture at pile cut off level
  • Easy adjustment
  • Complies with health and safety guidelines for hand arm vibration injuries

National Pile Croppers

About National Pile Croppers

Located in the very heart of England, with convenient access to all parts of the UK and beyond, National Pile Croppers was established in September 2015 and has grown dynamically to now being the UK’s leading supplier of pile cropping attachments. Bringing a huge amount of knowledge and passion to the industry, the management team has over 100 years of combined experience in the industry.

The company now focuses on providing a bespoke service to construction customers, by supplying the correct equipment for individual applications on time and at a very competitive price.

Over the past two years, National Pile Croppers have built a completely new range of redesigned and improved pile cropping equipment, all developed and built in house. All of National Pile Croppers’ machinery is available for customers to hire from its depots in Burton-on-Trent and Stevenage, with the company’s avowed aim to be the best at what it does.

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