[TowerTalk] To grout or not to grout (tower leg bolts)

[Dan Keefe]

Terry Dunlap wrote:
> 
> At 09:59 PM 4/1/97 -0500, K4OJ@aol.com wrote:
> >Grout is used frequently in commercial construction, there are several types
> >available, I remember metallic and non-metallic as existing but forget why
> >you want one or the other .  What grout is, is basically a very fine
> >concrete, which will flow very easily.....ie the mixed grout will pour/run
> >under your metal "feet" easily - it won't need to be forced to occupy the
> >cavity under the steel.  It will take the weight once it sets up and serve to
> >transfer it to the slab below it - rather than having your leg up on a
> >"stilt." as it is now on the bolts.  Frequently grout is used under heavy
> >machinery, the equipment is placed as you have done, onto threaded bolts -
> >levelled, and then: its grout time.
> 
> The main structural difference between grout and concrete is that grout is
> a non-shrink cementitous product.  This is true whether or not the grout is
> metallic or non-metallic.  This allows the grout to be "installed" in it's
> final position without it shrinking back during the setting process.  Most
> grouts can be mixed so that they can be "flowed" under the baseplate or mixed
> so that it can be "dry-packed" under the base plate or leveling fixture.  The
> choice depends on your particular application.  Normally, metallic grout is
> used in "repetitive motion" applications such as machinery with considerable
> vibration.  I don't believe that a tower would require this type.
> 
> 73 de Terry KK6T
> 

Concrete/grout is used in the construction of all large sewer and water
transmission pipe.

One of the reasons for using it is to encase the actual pipe which is
made of sheet steel and rolled in the form of a pipe on an angle. ( It
looks like a toilet paper roll. When the sheet steel is rolled in the
form of a pipe and welded at each seam large coils of rebar are wrapped
tightly around the metal roll for strength.

The final step in the process is to spray mortar (Gunnite is the process
name) on the metal parts of the pipe, both inside and out. The type and
quality of the mortar is important in the manufacture of concrete pipe.

The main reason for using mortar is to encase the metal parts of the
pipe in something that is both highly alkaline and oxygen proof so that
the metal parts cannot rust. There are other reasons but they do not
apply to this discussion.

Dan Keefe  KS6Z
Vista, CA


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