The patented Intelligent Sensing Control (ISC) has no sensors or electric cables at the front of the machine eliminating ingress of water, grease and dust problems. An on-board computer, which can be programd by the operator, automatically controls and manipulates the pre-set movement of the waterjet nozzle and the tracks or vertical hoist.
By combining the fluid dynamic, geometric and kinetic parameters of the control system, the Aqua Cutter will optimize the settings and apply the minimum required force to the material, removing only the deteriorated material.
Good sound concrete is left untouched and the reinforcement steel is left clean.
In total, around 45 m³ of concrete was stripped away to the rebar -- to an average depth of 5 cm -- by the high pressure water jet system.
The HVD removed an average of 0.9 m³ of concrete an hour, with the high pressure power pack PP480 operating at a pressure of 800 Bar, connected to the robot with a 100 m long hose. The pump's maximum pressure is 1000 Bar with a maximum water flow of approximately 200 liters per minute.
"In addition to its incomparable speed, another important advantage of the hydrodemolition process is the elimination of microcracks in the remaining concrete," said ISS specialist in the process Jörgen Boström. "Where there are cracks, there is air, and with air in the structure there's always the possibility of movement when temperatures change."
"Another advantage over traditional demolition methods, is that the water jets will get right behind the back of the rebar struts and remove the concrete," he added.
"You also, of course, have a completely clean and dust-free surface to work on when bonding the new concrete, which is not the case with jackhammer removal."
There is no vibration to the surface using the HVD robot, which also allows controlled and selective removal, minimizing the waste of good concrete and secure removal of the deteriorated concrete.
It also does not damage the rebars and causes no additional structure damage, in addition to eliminating the risk of operator injury caused by either vibration or heavy lifting.
"The HVD is the most comprehensive in the program and can operate either horizontally, vertically or under-up to a height of 6 m free standing, as standard," explained Aquajet Systems Sales and Marketing Manager Jan-Åke Petersson.
When operating vertically above 6 m the tower of the robot is secured in position at the wall, as was the case for finishing off this job, with the height of the dam wall being 8 m.
The demand and popularity of hydrodemolition is now growing worldwide, Petersson added.
"In Sweden and other Scandinavian countries, no other form of demolition is employed in the repair of structural concrete such as bridges. It is also now being specified in various German states," he said. "In addition, a new EU Standard is expected shortly and we believe it will push hydrodemolition even more forward."
Hydrodemolition is also gaining popularity in new markets such as India, China and Russia.
"Of course, a robotized, high-speed process could never compete on labor costs, but now these countries are looking more at long lasting repairs and efficiency," said Petersson. "The lifetime for maintenance and rapair carried out using Aqua Cutter hydrodemolition can almost be compared to the lifetime guaranteed by new constructions."
The renovation is running on schedule, and Norrköping should have its beautiful illuminated waterfall back by July.
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