If you take a look around, almost everything is based on rules. Education, employment, recreation, and social interactions all have rules that govern what we can and can’t do to ensure everyone is on an even playing field and we can reap the rewards of hard work. This is the way it’s always been, and always will be, and it’s been programmed into our minds since we were children so that we don’t even need to think about it anymore.
There are also many rules for the art of shotcreting to ensure the final product is optimal and the customer is getting what they paid for. For example, using the correct mix design is paramount to ensure a quality finish. The shotcrete components such as aggregates, water, cement, fine material, chemical additives, and fibres form a complex system which must be precise to achieve the best results. This is why it’s always recommended to use qualified and experienced shotcrete contractors to perform any shotcrete project.
Furthermore, using the correct spraying technique is critical in making sure the shotcrete adheres to the surface and to minimise rebound. To give you some insight into how to correctly apply shotcrete, we’ve compiled a list of our top shotcreting rules to achieve the best possible results.
- Cleaning the surface
Before spraying any surface, it must be examined for any loose materials and cleaned thoroughly to ensure there is no dust or other contaminants. Any loose materials or rocks which can fall must be removed to ensure a smooth operation. The substrate should be cleaned with water, air, or a combination of these methods.
- Correct distance between the nozzle and surface
The shotcrete process is based on the principle that concrete being sprayed at high velocity will adhere to the surface correctly due to the impact force. To achieve this, the nozzleman should maintain a distance of 1 to 2 metres from the substrate. If the distance is too short, there will be too much rebound and if the distance is too great, the concrete won’t adhere properly.
- Spray at a 900 angle
To ensure the best results, the nozzleman should spray the concrete at a 900 angle to the substrate to increase adhesion and minimise rebound. The spraying technique is paramount to the success of the project, and the nozzleman should use circular movements evenly over the entire surface to achieve a homogenous finish.
- Use a layering technique
The application of the concrete should be completed in layers, from the bottom of the substrate continuing upwards. The initial layer acts as a support layer and adhesive bridge for the following layers. The total number of layers and the thickness is governed by the project requirements.
- Cleaning additional layers
If a substantial amount of time has passed between the application of layers, the existing layer should be cleaned of any dust and other contaminants using water, air, or a combination of both to facilitate proper adhesion to the substrate.
- Clean the spraying machine after use
It’s paramount that the whole machine is cleaned properly after each use to eliminate any accumulation of material in the hoses, nozzle, concrete pump and additive pump. If any materials accumulate, they will damage the equipment resulting in discontinuity of the flow. This is a vital aspect of the correct maintenance of the equipment.
- Hydrate the surface
After the shotcrete project has finished, it’s essential that the surface remains moist for at least one week to maintain the compressive strength and to avoid any cracks appearing from the hardening process. Hydrating the surface is also known as curing and involves spraying water over the surface, using paper or plastic sheets, or adding specific additives to the concrete mix.
As you can, the shotcreting process is complex and involves many steps to ensure the final product is optimal and the customer is happy with their investment. If you’re looking to use shotcrete for your next project, look no further than the qualified and experienced team at Evolution Shotcrete. For more information on our range of services, phone our friendly staff on 07 5561 8885.