What is Hydrodemolition ?

What is Hydrodemolition and why do we use it ?

The industry trend is towards hydrodemolition and the guidance states that “wherever possible hydrodemolition should be the preferred method of concrete removal” (Journal of the Concrete Repair Association, Issue Number 10 page 4 “Cracking Matters”. There has been a legislative change in that The Control of Vibration at Work Regulations 2005 (the Vibration Regulations http://www.hse.gov.uk/vibration/hav/workingwithus.htm ), which came into force on 6 July 2005 and aims to protect workers from risks to health from vibration. The regulations introduce action and limit values for hand-arm and whole-body vibration. Therefore there is a need to remove the use of mechanical hand tools, which has necessitated the introduction of hydrodemolition techniques for the removal of defective concrete.

Hydrodemolition is used to replace the once favoured technique of a jackhammer or pneumatic breaker. These have become outdated as they remove both good and bad concrete and cause damage to the remaining healthy and sound concrete and steel reinforcement, as well injuring jackhammer operators.

Hand operated hydrodemolition uses between 20 - 60 litres of water per minute at a pressures of 1000 up to 2500 bar pushing 25 - 30kg of reaction force on the human body. Due to the physical requirements, an operator can sometimes only stand 10 or 15 minutes without having a break or rest. As the workday progresses operators become fatigued and because of this there is the potential for accidents to happen.

However hydrodemolition is not an easy or simple job; conventional hydrodemolition has traditionally involved an operator holding a lance, which is dangerous, monotonous and hard physical work. Ultra High pressure water jetting is therefore extremely dangerous. It can cause irreparable damage to human flesh so robotic methods have been developed over the past twenty-three years.

Robotic hydrodemolition is a fast efficient and method of concrete removal, without damaging the surrounding structure and embedded rebar, utilising the power of high-pressure water.

A jet of high-pressure water is directed at the surface of the concrete where it penetrates the voids and micro-cracks. When the water pressure inside the voids overcomes the pressure of the concrete a “blast” occurs. Removing damaged or poor quality concrete from sensitive structures such as bridges, dam walls, tunnels, docks, harbours, multi-storey car parking decks and runways. Using pneumatic and hydraulic breakers or road milling machines, is universally accepted as being inefficient and even damaging to the structure being repaired.