Understanding what spray on concrete is can mean the difference between a successful concrete project or one that is way off budget and expensive. The majority of people today are familiar with concrete as a building material. Although, not all of us know about a form of concrete referred to as spray on concrete or also called shotcrete. This article will describe spray on concrete, as well as the many ways it’s used in many different construction jobs at present.
Basically, spray on concrete is projected concrete. Invented quite effectively in the early part of the 20th century, spray on concrete was developed as a method for using concrete to fill in casting molds. Earlier forms of concrete were in a dry mixture which was pushed by air pressure straightaway into the mold by an air compressor.
Once the concrete was discharged, the dry mixture became wet, enabling it to get into and stick or adhere inside the mold, taking its shape. A Mr. Carl Akeley, who developed this technique, had this patented under his name in 1911 and included his concrete spraying device or ‘cement gun’ which was also invented by him. Mr. Akeley also coined the term gunite for the cementing material which it created.
More uses for spray on concrete soon become quite apparent. Since we could now spray concrete on any horizontal or vertical surfaces, the spray on concrete was easily applied on the sides of buildings and other structures, the spray on concrete could also be utilized as a patching material and also as filler if cracks may have shown themselves on walls or even in foundations and concrete bases. This technique also made the building of walkways faster in numerous front yards and patios as well, because spray on concrete could be installed in a just a few minutes as compared to the duration it took to blend and apply concrete manually.
Spray on concrete using the dry method was the standard practice until the mid 1950’s and continued to get better and more efficient. The dry method is still in use today and requires placing the dry mix into a hopper device, after which it is run into a hose with a water hose also attached at the end. When the concrete is pushed out of the hose with pressurized air and in the device, the worker simply corrects the quantity of water which is added to the dry mixture. This creates a concrete mix which is easy to point and shoot concrete with. It will set and cure in the similar duration of time as any other way of installing a concrete surface or slab.
During the 1950’s and 60’s another option for to spray on concrete was invented. Known as the wet method, this operation required the use of ready-mixed concrete. Similar to the dry method, air is pressurized and used to push the concrete mix into a hose and out of a spray nozzle designed specifically for concrete. In using the wet method, the hose operator will not need to correct the mix of water and dry concrete materials because that operation has already been done by pre-mixing the concrete. Users of this technique enjoy the fact there is no possibility of mixing too much water into the mixture, which may lead to a weak concrete texture and density. Proponents of the dry method believe that the correctly mixed concrete and water create a better product which is stronger and more durable than the ready-mix used with the wet method to spray concrete.