Shotcrete is used increasingly in mines for ground support. This is because of the advancements in equipment that are used to spray the material. There are also different mixes and combinations of shotcrete that are formulated for maximum strength. There are different types of fibres used for the material as well as advanced machinery and admixtures so it has made a definite improvement as a supporting element in underground mining.
Shotcrete is a term used for aggregates that are sprayed at high velocity through a hose onto a surface. There can be wet and dry mixes when it comes to shotcrete. Because there is a high force when it is ejected from the nozzle, it undergoes compaction as well. There are different ground support equipment that is used depending on the requirements and what is specified in the design of ground support. Spraying of concrete is a method that is used to stabilise structures during a short period of time and there is no need for the use of moulds. Traditionally, the tunnel profiles were lines to stabilise them but this practice is no longer done because of the ease of spraying concrete and the degree of support it provides. The mix of concrete sprayed will be determined by a professional by considering the level of support that the mine requires.
When mining is carried out underground, ground support is essential for the safety of the workers and the operation. And shotcrete is one of the quickest ways of providing support. If there is loose rock or if there are new tunnels being opened, shotcrete can provide strong support. It is used for above ground mining operations as well. The main uses for shotcrete in mining are stabilizing the excavated areas, lining of arches for short and long term durations etc. It is also used in other applications such as repairing foundations, bridges, walls, silos etc. It can be used in the construction of pools as well. When excavating underground, there is a lot of stress that is exerted in the excavated sections. There is a lot of flexibility that you get from shotcrete and you can modify the thickness of application, formulation of the shotcrete and you can re-spray the mixture anytime when required.
The lining of the tunnel is something that attests to the expertise of the contractor who is in charge of tunnelling. The final lining can be achieved by sprayed concrete and this is very durable. There are also rockbolts that are used to stabilize excavations and in between the rockbolts, shotcrete can be sprayed so that the entire area is covered. When the requirement called for high concrete quality and high output, wet sprayed concrete is used. Wet sprayed concrete is very efficient and it can improve the working conditions of the mine considerable as it doesn’t generate a lot of dust. When smaller quantities and outputs are called for, dry sprayed concrete is used. There is no wastage of concrete and it provides high early strength.