What Is Shotcrete? A Guide To Understanding Shotcrete and How It Works

Virtually every person has come across concrete before and will very likely see it every single day. Whether you're going for a walk on the sidewalk, getting the train to work, or enjoying a dip in your pool, you'll see concrete pretty much everywhere whether you realise it or not. But what about shotcrete? Although this concept has been about for over a century, it's still fairly unheard of despite the frequent applications it has in the construction industry today.

What is Shotcrete?

Shotcrete, also referred to as sprayed concrete or gunite, is effectively concrete that is pneumatically sprayed through the nozzle of a hose at high velocity onto a receiving surface. Utilised as an advanced construction technique, shotcrete is mainly reinforced by conventional steel rods or steel mesh, and has many benefits over conventional poured concrete.

As a result of the force of the nozzle, shotcrete is placed and compressed simultaneously meaning that it can be used on any kind of surface, form, or shape. Popular applications of shotcrete are for inground pools, retaining walls, tunnels, water tanks, drainage, and slope stabilisation. Any structure that depend on customisation in its shape and design can benefit drastically from utilising shotcrete.

History of Shotcrete

Shotcrete, traditionally known as gunite, was conceived at the beginning of the 20th century by an American taxidermist for the single aim of restoring the Field Columbian Museum in Chicago. This process involved utilising a hose with compressed air to blast dry material, while at the same time injecting water via the nozzle as the material was discharged. This is now referred to as the 'dry mix' method, and the creator, Carl Akeley, patented his concept as the cement gun (being the tool), and gunite (being the product). The nozzle is directed by skilled workers for modest jobs (for instance swimming pools) but is affixed to mechanical arms and remotely controlled for bigger jobs.

Dry Mix vs Wet Mix

Shotcrete was at first created using the dry mix method, which consisted of adding the dry elements of concrete into a hopper before spraying it pneumatically through a hose and nozzle. The individual in charge of the nozzle also manages the injection of water through the nozzle, so that when the shotcrete meets the surface, it is totally mixed. Therefore, this process requires a skilled nozzleman, especially when being used on areas that are heavily reinforced. The quantity of water injected at the nozzle can be conveniently calibrated, allowing for better placement in vertical and overhead surfaces without needing the help of an accelerator.

On the contrary, wet mix shotcrete involves utilising ready-mix concrete that is propelled to the surface by compressed air at the nozzle. The wet mix method is much more prevalent now than the dry mix method given that it creates less waste, less dust, and less rebound. Considering that wet mix shotcrete uses ready-mix concrete, larger volumes can be applied in less time than dry mix shotcrete.

Benefits & Properties

Shotcrete is considered a premium method of concrete applications due to the many benefits it offers over standard poured concrete. The leading benefit lies within the method of mixing, transporting, and applying the concrete, which is easier and faster than standard concrete methods.

Shotcrete likewise needs less water than conventional poured concrete and has a higher density and lower permeability. When this kind of concrete is applied at high velocity, the resulting product has a more substantial bonding capacity than traditional concrete and has 30% higher compressive strength, making it more reliable against freezing and cracking. Some other benefits include the ease of application in tough to reach locations, substantial cutbacks in the quantity of framework needed, the speed at which this kind of concrete can be applied, and lower maintenance requirements post application.

Where to Find Shotcrete?

There are many providers that supply shotcrete with fluctuating degrees of involvement in the application process. EvolutionShotcrete is one of Australia's leading providers, considered that they also offer Civil and Geotechnical Engineering recommendations regarding ground improvement, piling, micro piling, soil nails, anchors, and soil testing.

If you want to use shotcrete for your next project, or have any more inquiries relating to shotcrete in general, call us on 07 5561 8885, or visit our website for further information: https://www.evolutionshotcrete.com.au