What is Hydrodemolition?
|That’s the question we hear a lot! Hydrodemolition uses high-velocity water jets to remove deteriorated, delaminated, or contaminated concrete from reinforced concrete structures such as bridges, dams and parking garages. Yes, we remove concrete with water at ultra-high pressures (36,000 psi) and at waterjet velocities exceeding 1,500 mph. And the best news is that when operating at ultra-high pressure, our hydrodemolition process uses significantly less water than lower pressure systems, protecting the environment and conserving a valuable resource.The waterjets are very powerful and can remove 16 inches of concrete or more in a single pass. At the same time the waterjets do not damage the reinforcing steel or other embedded metal items.
Hydrodemolition plus our vacuum debris removal services, leaves the remaining concrete near pour-ready. Hydrodemolition is both an effective and efficient way to quickly remove deteriorated concrete and prepare the surface for the installation of a new concrete overlay or repair material.
Hydrodemolition is specified by State Departments of Transportation as well as restoration engineers who have experienced the significant advantages of hydrodemolition over traditional impact methods for concrete removal such as jack hammering and rotomilling.
Types of Hydrodemolition
Our computer-controlled waterjets can remove the concrete to provide a rough and bondable surface (scarification). Bond test have proven that a monolithic slab is formed when new concrete is place over a surface prepared using hydrodemolition.
When delaminations have occurred within the top mat of reinforcing or if the concrete is sound but chloride contaminated, hydrodemolition can be used to expose the top mat of reinforcing and remove all of the deteriorated and contaminated concrete. Typically the removal is to ¾” below the rebar allowing the rebar to be fully encased in new non-chloride containing concrete thus insuring the most durable repair possible (partial-depth or rebar exposure). Hydrodemolition can be used to remove concrete full depth (full-depth), when it is necessary to protect the existing reinforcing, shear studs or other considerations.
Based on the project’s specifications, we program our machines to remove the concrete to the specified depth; however, our jets can remove weak pockets beneath this depth, which further improves the structural integrity and longevity of the repair.
Demolition is only half of our job. Rampart has a fleet of vacuum trucks capable of collecting the debris and wastewater from the hydrodemolition process. We can also filter and reclaim the hydrodemolition wastewater and reduce the pH to acceptable levels so that it can be recycled or discharged in accordance with environmental regulations.
There are many advantages to using hydrodemolition over traditional removal methods, including:
- The rough, irregular surface profile provides an excellent mechanical bond for all types of repair materials creating a monolithic repair;
- The rough, irregular profile contains more surface area per square foot than any other type of concrete removal process;
- Surface micro-fracturing (bruising) caused by mechanical removal methods are eliminated;
- Exposed aggregates are not fractured, split or damaged and interlock with the overlay or repair material;
- Lower strength and deteriorated concrete (delamination) is selectively removed;
- Vibration to the surrounding structure is eliminated;
- Reinforced metal (rebar) is cleaned, eliminating the need for sandblasting;
- Reinforcing and other embedded metal elements are undamaged;
- Minimizes disruptions to users of occupied space by significantly reducing transmitted sound vibrations through the structure;
- Increase speed of concrete removal, which can reduce construction time;
- Minimizes dust and the potential for silicosis;
- Robotic units reduce labor and minimize soft-tissue injuries compared to jackhammers;
- Robotic equipment insures uniform removal.
What is a Hydrodemolition System?
A hydrodemolition system consists of:
Our ultra-high pressure pumps operate at 36,000 psi and either 32 gpm or 48 gpm. The robotic cutting tractor uniformly moves the waterjet over the surface controlling the quantity and quality of concrete removal. The support trailer transports the pumps, robotic tractor along with spare parts, tools fuel and water tanks to the project site.
What Controls Hydrodemolition Cutting Depth?
Simply stated, it is the length of time that the waterjet is directed at the concrete surface that determines the depth of removal, and contact time is controlled at the robotic cutting tractor.
There are five parameters that determine the quality and depth of removal. They are:
- Rotation speed of the nozzle
- Angle of the nozzle to the surface
- Height of the nozzle above the surface
- Traverse speed
- Advance distance
Rampart uses a variable speed-rotating nozzle, which can be adjusted from 0 to 1,800 rpm. In addition, the nozzle can be angled between 5° and 30° from vertical. When rotating, the angled water jet creates a demolition cone. By raising and lowering the nozzle the base of the cone can be increased and decreased in diameter. The robotic tractor moves the rotating nozzle back and forth on a traverse beam perpendicular to the direction of the tractor and tractor advances following a preset number and time for the traverse.
However, more important than how it is done is what it does? The robotic hydrodemolition process removes concrete in a safe, fast, predictable manner.
If you have a project and would like to discuss how hydrodemolition can help you or if you would like pricing or further information please contact us today.