Hydrodemolition is a fast and efficient method of concrete removal, without damaging the surrounding structure and imbedded rebar, utilizing 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. A robotic unit is used to accomplish a series of blasts in a controlled manner.
The high-pressure water is delivered to the robot through flexible high-pressure hoses. The hoses are connected to a lance, which is mounted in a gimbal. As the water travels down the lance it meets a nozzle. It is the nozzle that creates the high-pressure jet of water and the gimbal-mounted lance, which manipulates the jet. The lance is mounted in a roller assembly, which is attached to a beam. The roller assembly traverses the beam as the lance manipulates the jet of water. The robot operates fully automatically by its onboard computer system and it is controlled either by a lightweight hardwired or wireless radio remote. A shoulder harness is provided for operator comfort and ease of operation. 
The unique and innovative design of the Aquajet Systems “Aqua Cutter” a robotallows for control of the lance's angle of attack, lance speed, degree of oscillation, and the number of traverses required to remove the concrete to a determined depth and desired level of quality. This is referred to as “selective removal”. This means the unsound concrete will be removed while leaving the sound concrete with a superior bonding surface.
The bonding surface created by hydrodemolition resembles the craggy surface of an English muffin. This craggy surface has much greater bonding area than would be achieved by the use of jackhammers or other mechanical removal methods.
Independent “pull off” test have proven the bonding to be 50% or higher, than that of a surface prepared with jackhammers or sand blasting machines.
Percentage interface failures after different concrete preparation methods obtained from pull-off tests (Silfwerbrand1990(A)
As hydrodemolition is impact free there is no risk that the area treated will receive any impact or vibration damage. When rebar or other embedded steel is struck by a jackhammer vibrations will travel deep into the concrete to areas of sound concrete. Micro fractures and loosening of the rebar is often the result. This can create areas of potential future problems once the concrete is replaced.
Health and Environmental considerations:
The hazard of air borne silica dust and other particles is virtually
eliminated as the particles become trapped in the run off water. Safety is a primary concern at Aquajet Systems. We strive to make our equipment as user friendly and safe as possible. Emergency stops are placed on the Aqua Cutter robot and on the remote control. All equipment is tested and marked for a specific pressure.
Safety instructions are included in the Aquajet Systems hydrodemolition education package. Aquajet offers a full range of accessories for our Aqua Cutter hydrodemolition robots. These accessories allow you to perform work on walls and ceiling, parapet beams, columns, and even the underside of bridges. For jobs that can't be performed by our Aqua Cutter robots and accessories we have our standard Aqua Frame or special designed Aqua Frames.
Some nations require that all hydrodemolition specialists pass specific tests before work can begin on any public structure. The tests are performed on specially designed slabs of concrete to determine if the equipment and operators can perform selective hydrodemolition to the required standards. Please see pictures for samples of test slabs.
Hydrodemolition began about 25 years ago and is still considered a new technology. This method of concrete removal is gaining in popularity around the world and in some regions it is the only approved method for bridge deck repair.
Aquajet Systems has been in the hydrodemolition business since the early 80`s and have been committed to providing the industry with the best hydrodemolition equipment on the market. Together, with the aid of our customers, we continually improve our equipment. It is this dedication to both the hydrodemolition industry and our customers that have made us the world leaders we are today. In order to continue as a market leader we have developed a quality system that is ISO 9001 approved. Aquajet Systems are since 1997 the first ISO 9001 certified hydrodemolition manufacturer in the world.
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