Hydrodemolition removes a layer of concrete by shooting a jet of high pressure water into the material. When the water fills the natural cavities in the concrete, it bursts from within, exploding upwards. The result is a rough surface, free from micro-cracks, ready for a new layer of fresh concrete. It also leaves the reinforcement bars completely intact. Hydrodemolition can also be used for paint removal and surface preparation. A radio controlled robot (supplied with high pressure water from a pump) performs the demolition, keeping the supervising operator at a safe distance.

How does it work?

The robot is equipped with a lance that moves over the concrete surface, shooting a high pressure water jet and removing the damaged material. The operator sets the hydrodemolition parameters (cutting width, speed and jet angle, for example), positions the robot and starts the hydrodemolition process. When this is done, the robot works autonomously according to the set parameters, working its way in a straight line. All the operator has to do is monitor the progress and inspect the result. bilning A comparison with jackhammering shows all the advantages of the method. Not only do you avoid damaging the rebars and creating cracks deeper in the structure; since the procedure is remote-controlled, it increases worksite safety. Furthermore, hand- arm vibration syndrome (HaVs) as a result of vibrations from jackhammers is completely avoided using hydrodemolition.

Summary of advantages with the Conjet method:

  • One man, continuous operation.
  • Selective removal to a preset “quality depth”.
  • Up to 50% better bonding on rough surfaces.
  • Causes no vibrations or micro-cracks.
  • 25-50 times faster than jackhammers.
  • Removes concrete under rebars.
  • Removes rust from rebars
If you want to know more about the Hydrodemolition technique, read: (reprint from nordisk Betong no. 2-3:1988)