The Evolution of Hydrodemolition

In the early 1980s, the Swedish National Road Administration had a problem.

The conventional way to repair a bridge was to remove concrete with jackhammers, but core samples on projects revealed microcracks in the original parts of the bridge structures. The consequences of those tiny cracks were huge. They compromised the quality of the repair, which reduced how long it lasted and ultimately shortened the life of the structure.

According to the European Water Jetting Institute, this prompted the SNRA to seek a science-based solution and a new method of concrete removal emerged: hydrodemolition.

For those not familiar, hydrodemolition is a technique that uses a high-pressure water jet to remove layers of concrete. It’s an impact-free process, eliminating the impact responsible for microfractures. While the primary goal of the SNRA initiative was to remove microcracks from the equation, industry leaders identified additional benefits over time. By controlling the water jet mechanically, the concrete removal process became faster and more precise. These encouraging findings stimulated a whole new industry that has been preserving concrete structures for more than 35 years.

Turning up the pressure

Today, a full hydrodemolition system includes a robot, a high-pressure pump and a fully automated water treatment plant. The first systems included a semiautomatic robot to control a newly developed water jet and a high-pressure pump, which already existed for other types of waterjetting tools.

Pumps have evolved to be more reliable and offer higher and higher water pressure outputs. When hydrodemolition was in its infancy, for example, 14,000 psi pumps were being used. But in the high-pressure world, 14,000 psi is now the low range for pumps that go as high as 40,000 psi.

The greater range of pressure is desirable because it allows increased flexibility and precision. Water pressure, along with flow, are primary factors that affect the depth and speed of the removal. If an asset owner or engineer wants to only remove deteriorated concrete and leave the sound concrete intact, they might choose to operate at 15,000 to 20,000 psi to achieve a selective removal. But if the operator is charged with concrete surface preparation, for example, they can use 30,000 to 40,000 psi to achieve that goal. Having the choice to use the right pump for the project — whether higher or lower pressure — makes hydrodemolition an even more attractive option for concrete removal and surface preparation.

To make these pressure gains, however, equipment manufacturers had to improve pump design and component durability, which also increased reliability. Today’s most sophisticated pumps are long-running units that enclose the pump system, protecting workers if a hose bursts, for example. The enclosed pumps also protect workers from excessive noise. It’s possible to stand by an enclosed, silent high-pressure pump running at its highest rpm and carry on a conversation in a normal tone of voice.

Along with more refined, advanced pumps, industry stakeholders learned so much more about ultra-high-pressure water. Through decades of experience and the educational efforts of organizations like the Water Jetting and Technology Association and the European Water Jetting Institute, those who perform the work are masters in their field.

Increasing capabilities

When hydrodemolition robots were first manufactured, the basic idea was to control the high-pressure water jet to apply consistent energy to the entire concrete surface and control the depth of removal.

With increased demand to bring hydrodemolition to more types of projects, manufacturers engineer today’s machines to specialize in a wide range of concrete removal and repair jobs that go beyond the flatwork applications they were initially designed for. They are engineered with the capabilities to efficiently perform hydrodemolition overhead, on walls or below grade on roads and bridges, tunnels, dams, pillars, underwater structures and building interiors.

In hydrodemolition’s early days, most robots were controlled by manual hydraulic valves and basic relays. Machines had a limited number of electronics — they didn’t have computers to perform automated functions. And when a problem occurred, the operation needed to have someone with good mechanical knowledge to troubleshoot the machine.

Over time, manufacturers have gathered customer feedback and conducted research to take hydrodemolition robots from rudimentary machines to incredibly advanced pieces of equipment. Robots are now built with programming logic controllers, sensors and an operator interface. Their systems feature settings to cut different shapes like circles, triangles and rhomboids. They can even be programmed to seamlessly cut to different depths in one pass without stopping. The high-pressure lances themselves have been improved with better nozzles and better flow dynamics.

Historically, lances moved in either an oscillating or rotating motion, but in recent years, some manufacturers have discovered that combining the two movements to create a figure eight pattern provides optimal production without making pipe holes. The figure eight pattern creates a constant speed over the concrete surface that results in greater production and a rough but even finished product, leaving an ideal bonding surface for new concrete. This allows for longer-lasting repairs than what could have been achieved with manual impact tools.

Despite technological advancements, hydrodemolition robots have become much simpler to use with many more automated functions. Some even let users know when an error occurs to make troubleshooting more streamlined. Hydrodemolition robots are now designed to work reliably for long hours at a time on the job site. Dependable equipment and partnering with a responsive manufacturer with spare parts on hand helps ensure maximum uptime to get projects done on time.

There have been incredible leaps from the first hydrodemolition robot to today’s machines. And evolution will only continue. Utilizing the most state-of-the-art equipment gives contractors an advantage to get the highest-quality results and complete the longest-lasting repairs.

Environmentally sound

Hydrodemolition work can’t be completed without considering water management and how to treat water respectfully while following local regulations. Hydrodemolition by its nature uses water, so the industry has engineered solutions to help contractors take a proactive approach to properly handling, treating and even reusing wastewater.

Early on, before a manufactured solution existed, contractors often went to great lengths to cobble together a system to capture and treat the wastewater. It was time-consuming and labor-intensive, often requiring chemicals to treat the water and continuous manual testing. Some hired a third party to collect and treat the water, which increased the cost of the project.

Today’s water treatment systems are compact and fully automated, streamlining the process. The systems treat the hydrodemolition wastewater for pH and remove suspended solids, so contractors can either release it into sanitary or storm sewers, or recirculate the treated water through the equipment. By recycling the water in this manner, they greatly reduce the amount they need, which is good environmental stewardship and reduces water costs. Automatic, continuous monitoring makes it much easier to comply with local regulations and provide documentation that requirements are met.

A manufactured water treatment solution was a much-needed piece to the puzzle and a game-changer in the evolution of hydrodemolition.

The gold standard

Over more than three decades, the hydrodemolition industry has achieved many milestones. Overall knowledge about concrete repair has increased thanks to organizations like the International Concrete Repair Institute. Manufacturers continue to develop the equipment, making strides in productivity, safety, operability and environmental impact. And hydrodemolition contractors continue to build their expertise, offering the best solution to a decades-old problem.

That leads to the most elusive milestone. The goal for all stakeholders has always been to give concrete structures the longest possible lives. After more than 35 years, hydrodemolition remains the only impact-free mechanical method for removing concrete, which should make it the gold standard. We’re not there yet but remain optimistic that the industry will achieve this defining moment.

What will that look like? We’ll reach gold-standard status when asset owners request it as the process of choice for repair, when it is routinely specified by engineers for its benefits and when contractors use it any time prolonging the repair is the endgame.