Original Article: https://safetyculture.com/topics/hydrodemolition/

What is Hydrodemolition?

Hydrodemolition is a process of using high-pressure water jets to remove concrete, asphalt, or other materials from a surface. The process is also known as hydraulic grinding or hydro-jetting. Hydrodemolition typically use abrasive materials and is often used to remove damaged or deteriorated concrete from bridges, highways, and other structures. The high-pressure waterjet not only removes the damaged material but also cleans the surface beneath, providing a clean substrate for repairs. In addition to its power and efficiency, hydrodemolition is a safe and environmentally friendly alternative to traditional demolition methods.

Benefits of Hydrodemolition

There are many benefits to using hydro demolition over traditional demolition methods, such as:

  • Reduction of dust and noise pollution
  • Reuse of the collected water used in hydrodemolition
  • Filling out of small cracks after hydrodemolition because of high quality surface for bonding
  • Rebars remain undamaged even after demolishing Reinforced Concrete Structure (RCC) buildings
  • Works great in small areas and saves time and money
  • Most useful in industrial settings and lesser safety risks to operators

3 Methods of Hydrodemolition

There are three primary methods of hydro demolition:

Hydroscarification

Hydroscarification is a process that uses ultra-high pressure water jets to remove the top layer of concrete. The depth generally falls between 1/4 to 3/4 inches. It is ideal for removing surface imperfections or preparing the surface for resurfacing.

Partial Depth Removal

Partial depth removal entails the selective excavation of concrete with a depth of more than 3/4 inch. This method often repairs concrete damaged by freeze-thaw cycles or deicing salts.

Full-Depth Removal

Full-depth removal involves the demolition of all deteriorated concrete. For severely damaged concrete, it is usually the last resort.

What is the Equipment Used?

The most typical method of hydrodemolition is to use automated equipment such as a robotic cutting tractor that controls the water streams and thus the uniform removal of concrete. Additionally, high-pressure pumps and trailers collect and move water and fuel tanks. To minimize the danger of personal injury from debris, operators must wear protective gear.

High-pressure water jetting operates at 15,000 to 25,000 pounds per square inch (psi), while ultrahigh-pressure (UHP) falls in the range of 25,000 to 55,000 psi. Hydrodemolition uses about 20 times as much pressure as a typical household power washer.

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5 Common Concrete Errors That Hydrodemolition Can Help With

Contractors can use hydro demolition to speed up project delivery and minimize the impact of construction errors on the project. Here are five frequent concrete mistakes that hydro demolition may help you fix.

Formwork Failure

Formwork failures can result in a lot of wasted time and money. If the formwork fails to hold the concrete in place, it will have to be corrected using handheld equipment, which is slow, backbreaking work. Additionally, vibrations from the equipment can damage rebar and leave microcracks in the concrete, necessitating the demolition of most or all of the structure.

Concrete Segregation & other Batch Problems

Hydrodemolition can often solve batch problems such as concrete segregation. This process selectively removes material from the surface, leaving the sound concrete intact. Setting the robot to remove just the segregated material makes it possible to repair the concrete without causing further damage.

Off-Spec Imbedded Materials

Off-spec imbedded materials can be a real headache when removing them from concrete. Hydrodemolition is an effective method for removing these materials quickly and easily. The material is broken up using a high pressure pump of water. Hydrodemolition is a precise process, allowing contractors to remove just the right amount of material to reach the embedded item.

Concrete Repairs to Existing Structures

There are several methods for repairing concrete structures, but hydrodemolition is often considered the most efficient. It is because it can be used to selectively remove deteriorated concrete without damaging the sound concrete beneath. Additionally, it provides a clean surface for repairs, saving time and money.

Compressive Strength Failure

Compressive strength failure is when the concrete fails to hold up under pressure. Several factors can cause it, such as an incorrect mix design, weak aggregates, or poor workmanship. When it occurs, the concrete will usually crumble or crack. Repairs can be made to damaged concrete using hydrodemolition.

Drawbacks of Hydrodemolition

Some drawbacks of hydrodemolition are:

  • There will be a high runoff issue if water is not collected and controlled correctly.
  • Hydrodemolition needs water and sewage.

When hydrodemolition is used for vertical and overhead works, it can be hazardous if not used properly and can also result to an increased risk of injury.