Hydrodemolition is a concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 removal technique which utilizes high-pressure water to remove deteriorated and sound concrete as well as asphalt

Asphalt

Asphalt or , also known as bitumen, is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits, it is a substance classed as a pitch...

 and grout

Grout

Grout is a construction material used to embed rebars in masonry walls, connect sections of pre-cast concrete, fill voids, and seal joints . Grout is generally composed of a mixture of water, cement, sand, often color tint, and sometimes fine gravel...

. This process provides an excellent bonding surface for repair material and new coating applications. First developed in Europe in the 1970s, this technology has become widely accepted for concrete removal and surface preparation throughout Europe and North America.

Hydrodemolition is not used as much for demolition

Demolition

Demolition is the tearing-down of buildings and other structures, the opposite of construction. Demolition contrasts with deconstruction, which involves taking a building apart while carefully preserving valuable elements for re-use....

 as it is for surface restoration and protection projects. When concrete has deteriorated or the reinforcing steel has begun to corrode, it is necessary to remove any unsound concrete and reinforcing bar

Rebar

A rebar , also known as reinforcing steel, reinforcement steel, rerod, or a deformed bar, is a common steel bar, and is commonly used as a tensioning device in reinforced concrete and reinforced masonry structures holding the concrete in compression...

s (rebar) in order to replace it with new concrete and maintain the integrity of the structure. This process has also been used to remove sound concrete that is not compromised in any way. This may be done to install a preventive cathodic protection

Cathodic protection

Cathodic protection is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. The simplest method to apply CP is by connecting the metal to be protected with another more easily corroded "sacrificial metal" to act as the anode of the...

 system, or to remove concrete in structures in which vibration is a concern. Unlike jackhammer

Jackhammer

A jackhammer is a pneumatic tool that combines a hammer directly with a chisel that was invented by Charles Brady King. Hand-held jackhammers are typically powered by compressed air, but some use electric motors. Larger jackhammers, such as rig mounted hammers used on construction machinery, are...

s, hydrodemolition does not produce vibrations throughout a structure and therefore does not introduce micro fractures.

Applications

Hydro scarification

The process of hydro scarification (a.k.a. hydroscarification or scarification) uses ultra high pressure water to remove the top surface of a concrete bridge or road surface. Usually the removal is within 1/4" to 3/4" at the most, but can be of any depth above the top layer of rebar

Rebar

A rebar , also known as reinforcing steel, reinforcement steel, rerod, or a deformed bar, is a common steel bar, and is commonly used as a tensioning device in reinforced concrete and reinforced masonry structures holding the concrete in compression...

. Removal of this type is done in order to provide a good microfracture-free surface for bonding with new, sound concrete. (Lundy & Sujjavanich, 1997) Much like applying oil and chips to an asphalt road, this helps extend the useful life of the bridge decking and road surface by delaying the need for complete replacement.

Partial depth removal

Partial depth removal involves the selective removal of deteriorated concrete to a certain depth or of a concrete overlay to a depth exceeding 3/4". It is usually done in the case of concrete restoration projects where embedded objects such as rebar are substantial and need to be preserved.

Full depth removal

Complete removal of a concrete deck is done when it is too deteriorated to keep, but the structural concrete is adequate or can be easily repaired after the hydrodemolition has taken place. Precast concrete beams are often used in structures such as bridges and parking garages. Hydrodemolition has been used successfully to remove concrete over these beams, where alternate methods such as jackhammers might have caused fracture of the beams.

Structures

This technology has been used on the following types of structures: bridge decks and substructures, parking structures, dams

DAMS

Driot-Arnoux Motorsport is a racing team from France, involved in many areas of motorsports. DAMS was founded in 1988 by Jean-Paul Driot and former Formula One driver René Arnoux. It is headquartered near Le Mans, only 2 km from the Bugatti Circuit.- History :The year after its foundation,...

 and spillways, water treatment

Water treatment

Water treatment describes those processes used to make water more acceptable for a desired end-use. These can include use as drinking water, industrial processes, medical and many other uses. The goal of all water treatment process is to remove existing contaminants in the water, or reduce the...

 facilities, tunnels and aqueducts, nuclear power plant

Nuclear power plant

A nuclear power plant is a thermal power station in which the heat source is one or more nuclear reactors. As in a conventional thermal power station the heat is used to generate steam which drives a steam turbine connected to a generator which produces electricity.Nuclear power plants are usually...

s, piers and docks, stadiums, warehouses, transfer stations, and retaining wall

Retaining wall

Retaining walls are built in order to hold back earth which would otherwise move downwards. Their purpose is to stabilize slopes and provide useful areas at different elevations, e.g...

s.

Safety

Any process that is powerful enough to cut concrete can cut skin and bone. Operators of hydrodemolition equipment are required to wear protective equipment. For robotic hydrodemolition equipment, the operator wears steel-toed boots, eye protection, earmuffs and hard hat

Hard hat

A hard hat is a type of helmet predominantly used in workplace environments, such as construction sites, to protect the head from injury by falling objects, impact with other objects, debris, bad weather and electric shock. Inside the helmet is a suspension that spreads the helmet's weight over the...

. Hand lance operators wear steel-toed boots, metatarsals, shin guards and sometimes body armor

Bulletproof vest

A ballistic vest, bulletproof vest or bullet-resistant vest is an item of personal armor that helps absorb the impact from firearm-fired projectiles and shrapnel from explosions, and is worn on the torso...

.

Hydrocleaning

Surfaces of all types can get dirty from excessive use and abuse, water and air pollution and general exposure to the elements. These surfaces can be cleaned using high pressure water (hydrocleaning

Hydrocleaning

Hydrocleaning, high pressure cleaning or waterblasting is the use of water propelled at high speeds to clean surfaces and materials. By focusing and pressurizing the water stream, the force generated can remove, for example:...

) or high pressure water mixed with an abrasive.

Coating and sealant surface preparation

The use of high pressure and ultra high pressure water has been used to clean various coatings on concrete surfaces for the purpose of repair and reapplication. Coatings are used to protect concrete from the elements, rain, salt, and to create a friendlier surface for human use. Concrete can also be covered with carpet or tiles using a heavy duty glue or mastic. High pressure water can be used to clean these materials off when new carpet or tiles are desired.

Airfield rubber removal

Airfield rubber removal

Airfield rubber removal, also known as runway rubber removal, is the use of high pressure water, abrasives, chemicals and/or other mechanical means to remove the rubber that builds up on airport landing strips...

Commercial and military airfields are required to maintain certain levels of friction on runways to prevent planes from skidding. Runway design, weather and amount of rubber remaining from tire wear all play a role in the level of friction of a landing strip. If too much rubber is present, the friction of the landing strip

Runway

According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...

 will be less, requiring more distance for landings, especially in wet weather. High pressure water can be used to remove rubber and restore required friction.

Cold cutting

Cold cutting can be used to cut steel, concrete and other materials with the addition of an abrasive feed at the nozzle. Cold cutting is especially useful for cutting of pipes, vessels and tanks in areas where there is a requirement for no sparks or heat generated, such as chemical plants and oil rigs.