- This article was originally written by Mr. Roger Simonsson, Managing Director at AQUAJET, for the EWJI Yearbook 2020.
New construction isn’t always practical, so contractors need an efficient method to remove deteriorated concrete and create a suitable surface for new material. Traditionally, these methods require hours of manual labor using handheld water jetting equipment or pneumatic tools. However, to reduce injuries and increase efficiency, contractors are turning to Hydrodemolition for concrete rehabilitation applications, including roads and bridges, dams, piers, parking garages and other structures.
Here are five key advantages of Hydrodemolition:
- Superior bonding.
Alternative techniques such as handheld breakers leave layers of dust and damaged concrete with small cracks extending as much as 25 millimeters into the residual concrete. As a result, the profile potentially spoils the bonding for new concrete.
Hydrodemolition, on the other hand, leaves a rough, irregular surface. This “craggy” profile provides better bonding strength. Independent pull-off tests have shown that the bonding strength from Hydrodemolition robots is much higher than what’s achieved with a jackhammer or mechanical method. The average failure stress while using robotic Hydrodemolition can be more than 2 MPa.
- Extended structure lifespan.
Compared to jackhammers, Hydrodemolition is an impact-free process, eliminating the vibrations that cause microfractures — miniscule cracks in sound concrete that significantly damage the structure’s integrity.
Handheld pneumatic tools and milling machines also leave rebar damaged and susceptible to rusting. Although Hydrodemolition’s high-powered water jets are devastating to concrete, they don’t damage steel rebar. As a natural result of the high-pressure water, rust and scale is removed, leaving the steel clean and intact, even directly underneath. The method virtually eliminates “shadowing” as well.
This combination of benefits results in repairs that last up to three times longer. The Swedish Cement and Concrete Research Institute (CBI) determined a repair life expectancy of 21 to 35 years with Hydrodemolition robots compared to 7 to 12 years using mechanical chiseling.
- Increased productivity.
A Hydrodemolition robot’s high-pressure water jet removes concrete by widening existing pores and micro cracks in the weakened structure. This process is more efficient than mechanical methods, allowing the user to complete jobs more quickly. In some cases, contractors have seen results up to 25 times faster than with hand lances.
A Hydrodemolition robot and a single operator can complete concrete removal tasks as fast or faster than multiple workers.
Additionally, Hydrodemolition robots’ compact nature allows them to reach tight, confined spaces. Various design features and additional attachments also allow for work on vertical, curved or horizontal surfaces. This greatly increases productivity and reduces the number of tools needed on a jobsite.
- Less labor and more safety.
Hydrodemolition units require less labor and cause fewer injuries than other methods, such as chipping hammers and handheld water jetting equipment.
The robots allow operators to monitor work at a safe distance from hazards such as flying debris, harmful silica dust and ledges common in bridgework. Additionally, by eliminating the need to stand near a ledge, contractors save time otherwise spent setting up fall abatement systems.
The combination of high pressure, water volume and precise, robotic-controlled movements creates a powerful, efficient system that allows operators to take a hands-off approach. This eliminates fatigue and long-term injuries, such as nerve damage and hand-arm vibration syndrome, common with handheld equipment. These injuries can result in more worker’s compensation claims down the line and may cause company insurance premiums to increase.
- Less interference.
Finally, Hydrodemolition offers a quieter solution for urban environments.
Hydrodemolition robots generally produce less noise than handheld pneumatic tools since the sound is limited by the machine’s hood. Additional reduced-noise equipment used to provide high-pressure water to the robots is also available. The quieter operation allows contractors to work in residential areas or avoid busy travel times by working during hours when noise levels are restricted.
Hydrodemolition continues to grow in popularity with contractors, project stakeholders and government agencies around the globe. The machines’ ability to tackle projects in record time while improving safety is appealing to those looking for ways to speed up concrete removal while increasing ROI.