Views:7 Author:Site Editor Publish Time: 2018-06-15 Origin:Site
In the Beginning
Since the beginning of the shotcrete process development, advancements in shotcrete technology have increased dramatically because of the trusted relationships between the industry and the research community.
Equipment technology for the sprayed concrete industry was first developed in the early 1900s. Carl Akeley, a famous hunter and professor, devised a method for spraying plaster onto a wire frame for taxidermy purposes. Using compressed air, dry material was pushed through the nozzle of a gun-like device, where it was wet with water as it was blown onto a frame. The outcome was a strong, thick plaster coating that didn’t slump from the frame or set before being fully placed.
The equipment was subsequently used to patch deteriorated concrete using a dry mixture of sand and cement. The results were excellent, and patents and trade names were applied for in 1910 for the new “Cement Gun” and the “Gunite” material it produced.
This dry-process technique was utilized for the next 40 years, until a new process was developed in the 1950s that involved the use of pressure tanks to force stiff mortar through a hose. This new wet-process became known as shotcrete.
Understanding the Process
Shotcrete is defined as more of a process than a material or a product. Before you choose a piece of shotrete machine for a job, you need to understand the different processes used in shotcrete placement.
Shotcrete’s high strength, durability, low permeability, excellent bond and limitless shape possibilities can be achieved with either the wet- or dry-process, making it superior to high-quality conventional concrete. Both the wet- and dry-processes have been made almost interchangeable by advancements in both material and equipment technology over the years, with each still touting their own benefits.
The dry-process entails first placing pre-blended dry or semi-dampened materials into the shotcrete equipment’s hopper, which is subsequently metered into a delivery hose. Then, compressed air conveys material at high velocity to the nozzle, where water is added. Lastly, the material is consolidated on the receiving surface by the high-impact velocity.