Shotcrete and Gunite | Difference Between Shotcrete and Gunite | Features

Shotcrete and Guniting are important terminologies that are followed in the civil construction. The two methods have proven to be beneficial in the applications of soil stabilization, slope protection in swimming pool construction, fluid tanks, tunnel, in the works relating to concrete repair and many.

The difference between shotcrete and Gunite is actually a matter of concern in some countries of construction alone. Say the American Shotcrete Association(ASA) do not use the word guniting. They are only aware of Shotcrete, that can be carried out in the dry mix and wet mix.

Shotcrete and Guniting

The process in both the methods involves spraying of the concrete or the mortar mix pneumatically with the help of a spraying gun or nozzle. This is done at a higher velocity on to the surface of application.

When the mix used to spray is dry, the method is called as guniting. When a wet mix is used in the process of spraying or application, the method is called as shotcrete.

Dry Mix Process or Guniting

The preparation of dry mix will involve:

Fig.1.Guniting a Pool

1. Mixing of cement and aggregates in dry condition inside a bin

2. Pumping the dry mix through a hose using compressed air with a higher pressure through a spray gun.

3. At the nozzle of the gun, water is introduced to the dry mix. This happens just before the mix comes out of the nozzle on to the surface

Wet Mix Process or Shotcrete

The preparation of wet mix will involve:

1. A pre-mixed concrete or mortar is sprayed in high pressure on the surface

2. These methods eliminated the need for adding water at the nozzle

Fig.2.Shotcreting for Reinforced Walls

Difference Between Shotcrete and Guniting

	GUNITING OR DRY SHOTCRETING	SHOTCRETE – WET PROCESS
1.    History	The first technique of spraying concrete under pressure and high velocity by using a spray -gun developed in the US. The use of gun gave the name guniting	The technique of spraying concrete that came after guniting in the 1930s. This was conducted by using a nozzle spray. The mix can be dry or wet
2.    Mix	The guniting process is a trademark given for shotcrete process carried out with the dry mix. This process can also be known as dry-mix Shotcreting	The shotcrete process can be done with dry or wet mix and hence can be called as dry-mix shotcreting and wet mix Shotcreting
3.    Size of Aggregates	Smaller sized aggregates are used in the range of 10mm or so	Maximum size of aggregates is 1 inch for the wet process of shotcrete
4.   Strength of Product	Less strong Product than wet Shotcreting	Stronger product that guniting
5.    Quality Control	Quality Control is less compared to wet process	As the wet process will involve premixing of all the ingredients of the mix before pumping through the gun, a better quality of the product is obtained, unlike Gunite.
6.       Rebound Property	The spraying of dry mix tends to make it rebound off the surface and hence fall off.	The rebound in wet Shotcreting is less compared to guniting
7.    Waste	More – Due to high rebound of material	Lesser – less rebound of material
8.    Applications	Small Quantity of Work	For large quantity of work
9.   Labor and Experience	High-skilled labor who knows to properly control and operate the nozzle so that a good mix is sprayed out reducing maximum rebound.	As the ingredients are premixed before spraying there comes the need for normal operating labors.

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