What is the shotcrete process?
The shotcrete process involves discharging either mortar or high-performance concrete out via a spray gun, usually onto a vertical or overhead surface. Using a compressor, the material is pneumatically shot out at high velocity in a spraying motion, and the force of the back -and-forth action leads to the material compacting to form a monolithic film of concrete. The speed at which the process operates and application’s flexibility makes shotcrete particularly attractive for the construction industry. It is the preferred method of stabilisation and aesthetics in the construction of tunnels, reinforcement of slopes, and projects where variable thicknesses or thin layers of concrete is required.
What is the advantage of shotcrete?
Shotcrete can help form any shape, is easily coloured, and can be sculptured after application, meaning it can be used for a variety of concrete structures: artificial rock walls, zoo enclosures, mines, subways, pools, and dams to name a few. The method has evolved and been redeveloped throughout the years to increase its precision and efficiency.
How to choose the right shotcrete compressor?
It is vital to choose a right compressor to get the job done efficiently. There are 3 parameters critical: pressure, free air delivery and the fuel consumption. Read more below on how Atlas Copco makes sure to deliver the best performance for each of these factors.
3 parameters to take into account
1. Free Air Delivery
Selecting a compressor with enough FAD is crucial for shotcrete. The FAD of the compressor will affect the velocity of the material coming out the nozzle/spray gun, which will affect the shotcrete speed and hence influence, productivity, efficiency (waste of material) and the quality of shotcrete as well.
The PACE technology of Atlas Copco enables the compressor to increase the FAD as the pressure is reducing. Sometimes, the nominal FAD is not enough due to a leakage or bigger nozzle. When this is the case, the extra FAD increase by PACE will help a lot to optimize your shotcrete application.
The maximum working pressure is another important factor for shotcrete. Material moving inside the hose will cause friction, meaning that a higher pressure is needed to push the materials through the hose.
The longer your hose and the higher the worksurface, the more pressure is needed. Atlas Copco's PACE technology enables the compressor a maximum adjustable working pressure. This way, you can set your required pressure for your specific job to get the best productivity.
3. Fuel consumption
Fuel consumption plays of one the biggest role in operating costs and can go up to 3-5 times the price of your compressor during its whole life time. To increase the return of your investment, Atlas Copco is offering the most fuel efficient compressor thanks to the in-house designed compressor element.
With this in mind, Atlas Copco’s medium air range is the ideal choice. Our compressors are fitted with PACE technology, and enable the user to define pressure while the machine regulates the flow - putting users in full control of any project. These portable air compressors make the ideal partner for projects where power, mobility and efficiency are essential.
For shotcrete projects with a nearby supply of electrical energy, how about our E-Air range? These state-of-the-art electric compressors produce a reliable supply of clean, dry, oil-free air - ideal for maintaining sufficient nozzle velocity for all parts of the work. The E-Air’s VSD motor is compact, quiet, and offers unrivalled energy efficiency. Above all of this, electric compressors also further reduce your operation costs. Thanks to the VSD motor, the power limitation function even allows the compressor to operate at a low power grid. A true game-changer when it comes to performance, even in the toughest conditions.
We are currently using 2 E-Air units to tackle a challenging shotcrete project, often in monsoon weather conditions, reinforcing excavations whilst trying to maintain the structure of the rocks for the Mumbai-Pune Expressway in India. This project will reduce the travel time with up to 45 minutes.