What Is Better Gunite Or Shotecrete

[chilo]

I would like to know what is better gunite, concrete, and or shotecrete. And can you do the floor out of concrete and the walls out of shotecrete.

[masanori]

In Nov 2010 I had shotcrete pool installed. Right now I have the shell only. they will come back in the spring finish with diamond brite. I am happy with it.The pool used 4500psi concrete.

[quantumchromodynamics]

I don't think that there is a clearly superior product. There are many factors that go into the strength and durability of the structural shell.

1) The experience and expertise of the builder.

2) The thickness of the shell.

3) The strength ratings of the concrete.

4) The diameter and spacing of the rebar.

5) The preparation of the ground.

As for mixing application types, you don't want to do that. The shell should be shot in one continuous process to achieve a monolithic structure with no cold joints.

[txpoolguy]

Perhaps someone can explain the difference between the two. In N. Texas, we use gunite, but shotcrete didn't sound much, if any, different.

[Mark]

Shotcrete is a general term for both wet and dry application but is often incorrectly used to describe just the wet application. Gunite is strickly a dry application. With a dry application, it is much more important to have an experienced nozzleman becaue the gunite is mixed at the nozzle and if not done correctly can lead to problems. So if done properly both wet and dry shotcrete should be equally strong however it is easier to screw up the dry application.

The best place to learn about both is shotcrete.org. From their web site:

Shotcrete is an all-inclusive term to describe the spraying of concrete or mortar that may be accomplished through either a dry- or wet-mix process. Gunite refers only to the dry-mix process in which the dry cementitious mixture is blown through a hose to the nozzle, where the water is injected immediately prior to application. Because complete mixing of the water and dry ingredients is not possible in the nozzle, mixing is completed as the material impinges on the receiving surface, through manipulation of the nozzle. This requires a very highly skilled nozzleman, especially in the case of thick or heavily reinforced sections. Large aggregate is seldom used with the dry-mix process. Wet-mix shotcrete involves pumping of a previously prepared mixture, typically ready mixed concrete, to the nozzle. Compressed air is introduced at the nozzle to impel the mixture onto the receiving surface. The mixture usually contains minus 1/2 in. aggregate, although larger-size aggregate has also been used.

The use of the term “shotcrete” first occurred in Railroad Age magazine more than 50 years ago in place of the then proprietary word “Gunite,” and has been used by the American Concrete Institute since at least 1967 to describe all sprayed concrete or mortar.