The technique of using high pressure (HP) or ultra high pressure (UHP) water jets to cut and remove concrete from a structure is known within civil engineering as hydro demolition.
The principal benefit is that the water jet leaves steel reinforcements and/or structural embedments undamaged and ready for re-use.
This method is widely used in the alteration or repair of structures in many industry sectors.
It is now recognised by civil engineers, structural engineers and consultants as the safest, most effective, vibration-free method of concrete removal. The remaining structure suffers no cracking, reinforcing steel is left undamaged and the concrete retains its original integrity.
Removal of new concrete that has been placed in the wrong place, has not reached the correct strength or was poured without the steel reinforcement in place
Removal of existing concrete to allow tying into existing structures e.g. concrete pockets can be accurately cut
Removal of concrete to preserve expensive steel fabrication
Removal of concrete in close proximity to water/gas mains and high voltage cables
Removal of concrete damaged by salt and other chemicals
Removal of concrete under water
Removal of coatings, laitance, waterproofing, aggregate exposure, spalling or damaged concrete
Concrete surface preparation for bonding with new concrete (scabbling)
Preparation and protection of steel structures
Removal of concrete blockages inside pipes
Methods of Hydro Demolition
There are a huge range of applications for hydro demolition in civil engineering – and each requires a suite of lances, nozzles and accessories. These are linked to trailers or truck-mounted pumps with an output waterflow range of 20-250 litres per minute and working pressure up to 3000 bar.
Hand held safety lances are particularly suited to the removal of small volumes of concrete or stone and are ideal where access is restricted and where precision cutting is required. Each lance can work safely up to 3000 bar and can cut both concrete and aggregate to achieve accuracy to the millimeter (mm)
Gimbal-mounted recoil-less lances can be over four times as productive as hand held lances.
This option is ideal for large volume removal jobs in conditions where manual control is required and where access for robotic removal is impossible or ineffective.
Gimbal-mounted lances enable operators to manually control the full potential of jetting units up to 450kW. They incorporate a lock for barrel length adjustment, which means that we are able to cut concrete over one metre thick, deeper than with either a robot or a hand held lance. Safe control of the Gimbal is achieved using a multi-directional clip system that fits on to any standard site scaffolding, which acts as a track for improved accuracy.
Risks associated with high nozzle reaction forces are minimised and operator fatigue is reduced – thus improving safety and increasing productivity.
Hydro demolition robots are generally used for mass removal of concrete up to 200mm in depth. Robots are suitable for deck work and also adaptable for soffits and walls up to six metres in height with a standard tower section fitted. They are usually used in conjunction with hand lances and/or gimbal-mounted lances for trimming up.
Robots are in most cases controlled by a single operator and the design ensures that high removal rates are maintained over long periods, thus making them a competitive concrete removal option.
Robots range in size. We have lightweight, portable units which can be deployed by hand and assembled in areas with restricted access. Larger, heavy duty tracked units, which weigh in the region of two and a half tons, are completely portable with their own diesel engine and hydraulic control system. Electric-powered options are also available for work in enclosed areas where exhaust fumes are an issue.
The set up time is kept to a minimum, as the system is fully integrated and self-contained. Simple remote control means that depth and width of the cut is easily managed.
In addition to the mass removal of concrete, this robotic system can be used for scabbling, laitance and coatings removal. A powerful vacuum waste recovery option is also available.
Cuts to any depth
Can precision cut cement and aggregate to tight tolerances
Creates no percussive noise or vibration
Does not cause micro cracks in the structure
Does not damage reinforcing steel or cause loosening within the structure
Superior surface is created for bond with new concrete or coating
Safety and Environmental Advantages
Removes chlorides and other non-visible contamination
Uses mains water which is captured and treated, thus causing no contamination to the environment
Tools of the Trade
The StoneAge Blackhawk BHK-100 is a cost effective and high performing system for concrete hydro-demolition and scarification applications. It is specifically engineered as an attachment to standard flow hydraulic machines, offering a significant cost savings over robotic drive systems. More effective than jackhammering for concrete removal
Does not negatively affect sound concrete or introduce fracturing into the structure
Designed for horizontal, vertical or angled applications
Adaptable to your choice of implement (skid steer, telehandler, etc.)
Completely integrated hydraulic controls
Designed for use at any orientation
Effective for concrete scarification, partial depth cutting, or complete removal
Ideal for use on bridges, roadways, garages, and difficult to reach locations