A technique of cutting concrete that uses no heat or spark is to use a water jet. Water jet concrete cutting uses compressed water that travels at twice the speed of sound to cut through concrete. The water used is at a high pressure, over 25,000 psi. This allows precise control over the cutting, resulting in the creation of complex shapes.
The water jet used for water jet concrete cutting contains abrasive particles and travels at up to 750 metres per second. The abrasive acts to erode the material it is focused at in a similar manner to saw cuts, but on a smaller scale.
One of the reasons for the popularity of water jet concrete cutting is that it meets even the strict environmental laws. It generates little dust due to the use of water, as there is no metal edge to sharpen, and no heat or spark generated during cutting. There are also no finishing steps required as the cut produced by the water jet is perfectly fine. The forces involved make the use of water jet cutting with robotics possible.
The machinery used has a high initial cost, ranging from £12,000 to £300,000. In addition, the noise from the water jet can reach as loud as 110dB (or 90db if a proper catcher is used). Finally, there is a need to replace the nozzle every 2-6 hours as it wears very quickly. These costs need to be taken into consideration when you look at the alternative possibilities and what their costs are – especially including safety and environmental risks.
Water jet concrete cutting uses cutting heads that are driven by hydraulics by an operator that is some distance away. The remote operation means that the system is very safe, allowing for the use in dangerous environments including where radiation is present, underwater or where explosives exist, since the process does not generate any heat or spark.
This provides a great deal of safety for the workers, which is one of the reasons that this method is popular – despite some of the higher costs in comparison to what else is available in the industry.
Reinforced concrete piles are able to be cut using water jet concrete cutting, including ones that are 2m in diameter. Another use of this technology is in removing concrete that has deteriorated from decks or bridges. It is also possible to use the technology in a low pressure state, which allows concrete at the surface to be removed, but nothing below around 25mm. Beyond concrete, this process can cut a range of other materials such as bronze alloy, stone, iron, wood, steel and glass.
Most companies who employ water jet concrete cutting as a method of cutting also use other methods. A survey finding pneumatic hammer, a power saw with a diamond blade, torches, grinders and hydro blasting are all used as additional methods to water jet concrete cutting. This is to ensure that there is always the right tool for the right application so that the job is done correctly without destroying the integrity of the project.