Gunite/Shot-Crete? 1

[11echo]

I'm semi familiar with Gunite, but a new term has popped up in front of me "Shot-crete". Is this something different? ...OR basically the same thing? THX! ...Mark

 

[DMcGrath]

I think the two terms are used in somewhat the same context, but I think the difference is in how it is actually mixed when applied. Gunnite is the older of the two, and it is applied using a premixed cement and damp aggregate that has water added as it leaves the nozzle. Shotcrete is already mixed with water, and additional air is added as it leaves the nozzle. ACI 506R, "Guide to Shotcrete".

As far as which is better, I believe shotcrete is the more modern choice as it can be used to repair structural concrete or serve as a structural component in a tunnel lining, for example.

 

[11echo]

DMcGrath ...We are using this on a 3 ft tall earthen berm, where there is heavy access (not vehicle). Would it be more "economical" to do a "gunite" cover or "shot-crete"??

 

[Rjeffery]

Both are pneumaticlly applied concrete. Gun-ite is a trademarked method (If memory serves) The cost of either method is comparable if your ready mix supplier is within a reasonable distance of the project.

 

[henri2]

Check question number 1 in link

http://www.shotcrete.org/ASAfaqs.htm

 

[PEinc]

Shotcrete can be either wet mixed or dry mixed. Wet mixed is usually ready mix delivered in a concrete mixer. The wet mix often has smaller aggregate than regular concrete and extra cement for pumpability. Gunite is a dry mix shotcrete. The water is mixed with the cement and aggregate at the nozzle under high air pressure.

 

[PEinc]

Also, shotcrete by itself is not usually used to support slopes or "berms with heavy access." Shotcrete protects a slope or berm from erosion or it holds earth or rock in place between soil nails or rock bolts. Shotcrete is usually applied in relatively thin layers (3" to 12") which, by itself, usually isn't enough to provide slope stability.

 

[cvg]

gunite is a trademarked name for the drymix which is generally not in use any more. Shotcrete is the current name for the same product either dry or wet mix. In my experience, the dry mix process is rarely used anymore. If done properly, shotcrete has similar properties to cast in place concrete and is often used for structural applications where forming is difficult. Generally for slope protection and tunnel lining.

 

[msucog]

good early compressive strengths for shotcrete is what i'm seeing on a project of mine.
3000psi+ @ 1 day
4000-5000psi+ @ 7day

 

[dicksewerrat]

When I worked in Minnesota, gunite was premixed wet material as it went into the pump. shotcrete was dry mixed until it hit the mixing nozzle where water was added.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[rday]

I believe shotcrete is the generic term for pnumatically applied concrete. ACI 506 is the Guide to Shotcrete and I doubt ACI used a trademarked name.

Gunite is a trademarked product, though I can't recall if it is a wet or dry mix. We used it in pools when I did that work many years ago.

 

[PEinc]

http://en.wikipedia.org/wiki/Shotcrete#Shotcrete_vs._gunite

Shotcrete vs. gunite
Shotcrete is today an all-inclusive term that describes spraying concrete or mortar with either a dry or wet mix process. However, it may also sometimes be used to distinguish from gunite as a wet-mix. The term shotcrete was first defined by the American Railway Engineers Association (AREA) in the early 1930s.[2] By 1951, shotcrete had become the official generic name of the sprayed concrete process. [2]


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. Gunite was the original term coined by Akeley, and trademarked in 1909, patented in North Carolina. The concrete is blasted by pneumatic pressure from a gun, hence "gun"-ite.

The term "Gunite" became the registered trade mark of Allentown the oldest manufacturer of gunite equipment. Other manufacturers were thus compelled to use other terminology to describe the process such as shotcrete, pneumatic concrete, guncrete, etc. Shotcrete emerged as the most commonly used term after gunite and after the later development of the wet process came to used be for both methods.

THE END

 

[queque]

Does anyone have shotcrete aplication cost data by region? distance? etc?