Renovation and replacement of deteriorated concrete bridges, substructures, and roadways are of vital concern to highway and bridge maintenance personnel. As the demand for safe and efficient selective demolition work increases, so does the demand for better methods to expedite the demolition process. 

Conventional methods for removal of deteriorated concrete traditionally include jack hammering. In recent times, however, there has been a decline in the use of this equipment, probable reasons being that new alternatives have emerged and its following disadvantages. 

DISADVANTAGES OF JACK HAMMERING

• Unnecessary removal of sound concrete along with bad concrete
• Vibration generates micro fractures in sound concrete
• Micro fracturing of sound concrete due to vibration
• Unintentional damage to rebar
• Uncertainty as to complete removal of deteriorated concrete and corrosive chlorides
• Vibration injuries in fingers and arms of the operator.
• It is time consuming
• Dust formation and noise level are also high

PressureJet’s high pressure water jet system eliminates these negative results by utilizing high pressure water jetting techniques, Hydro-Demolition. The Hydro-Demolition process is successfully utilized to remove deteriorated concrete, leaving sound concrete with a rough profile, perfect for bonding the newly poured overlay. Hydro demolition is a relatively new method of removing select portions of a hardened concrete structure. 

Hydro-Demolition is a technology that uses extremely high pressure water jet that is capable of removing concrete while not damaging the rebar. The practical application of this technique makes it an extremely effective and efficient method of concrete removal. This is due to two main factors, one being the direct impact of the water jet on the surface. The other is the porous nature of concrete, the high pressure water is forced into the tiny cavities and cracks within the concrete mass, causing it to fracture and split. 

Hence, this high pressure water jet equipment breaks up concrete by disintegrating the cement matrix between aggregates. The demolishing effect can be tightly controlled to a desired level of removal, ranging from light scarification of the surface to deep penetration of the structural element. The use of the hydro demolition process has several advantages over conventional concrete removal methods, such as jack hammering. 

ADVANTAGES OF HYDRO-DEMOLITION

• Selective Material Removal The variable parameters of the technique, water pressure, jet size and speed of application, make it possible to demolish and remove concrete in a very precise and controlled way. These variables enable selective removal of deteriorated or de-laminated concrete, as the jet stream penetrates the cracks and faults in the degraded material more quickly, leaving the sound concrete intact.

• Accurate Material Removal The equipment can also be set to remove concrete to predetermined depths. These capabilities make it a very suitable method of enabling repairs to concrete structures, as it allows accurate removal of material, leaving the sub-structure and steel reinforcement intact if required.

• Leaves an exposed, washed and scarified surface on the aggregate, providing an ideal surface for the bonding of new layers.

• A rough, irregular surface profile is created to provide an excellent mechanical bond for all types of repair material.

• Surface micro-fracturing (bruising) caused by mechanical removal methods are eliminated.

• Removes corrosion and mortar paste.

• Reinforcement is cleaned and undamaged

• Can precisely and selectively remove damaged or deteriorated concrete, leaving sound concrete intact.

• No vibration reduces unnecessary de-lamination or damage to adjacent structures.

• Embedded reinforcing can be exposed and cleaned of rust and scale without damage.

• Provides excellent bonding of exposed substrate to new layers due to its cleaning action.

• Dilutes chloride ion concentrations at bonded surfaces.

• Is faster and more efficient than conventional mechanical methods of demolition.

• Minimizes labor injuries.

• Rebar is cleaned, undamaged, and free of corrosive chlorides

• Saves time in demolition, as well as eliminating time consuming rebar replacement and repair

• Vibration to the surrounding structure is eliminated.

• Minimizes disruptions to users of occupied space by significantly reducing transmitted sound through the structure.

• Increased speed of concrete removal can reduce construction time.

• Minimizes dust and the potential for silicosis.

• Structural vibration is minimal.

Due to above obvious advantages, hydro demolition has become a first choice vis-à-vis other conventional methods. It’s no wonder why so many contractors and other construction personnel are switching to the power of water jetting for Hydro-Demolition.