[TowerTalk] Tower base removal

[Jim Lux]

On 11/2/11 7:56 PM, jcjacobsen at q.com wrote:
> Rob needs to remove a big 'ol chunk of concrete:
> <snip>
> Once the tower is gone, the widow really wants to have the concrete base gone too. My
> suggestions of building a deck over it was not an option. I remember you
> guys talking about using a jackhammer to remove the top .............................
>
> --rob
> K6DQ
> <snip>
>
> Rob,
> I've thought this thru at times because I'm going to have to do the same thing when I sell this house down the road a bit.
> #1. If the base is real close to the house, a jack hammer may disturb/crack/rattle/harm the foundation in someway.
> #2. IF you go that route, dig the dirt away from the side of the concrete so that it has some place to "expand" into as the hammer goes down.
> #3. I'm currently thinking of scoring the base with a concrete saw as deep as I can then split it off.
>
> #4. Someone suggested expanding clay in holes. Maybe
> #4. OR take a page from stone workers who use the little feather and wedge things in holes drilled into the "rock". They are placed in the holes and then hit with a large maul, working back and forth from on to another until the rock splits.
>

If it worked for ancient and modern Egyptians quarrying obelisks out of 
Aswan granite, why not.  Small hole, insert wood wedge, add water. Wood 
swells, causes crack along cleavage plane. You can also do it with metal 
wedges all along a line, and whacking them one by one.  (I watched them 
do this last winter.. tedious, but it does work)

Too bad it doesn't work for reinforced concrete very well.

After the Sylmar earthquake, there were collapsed freeway support 
columns that were essentially indestructible.  So much rebar that they 
were immune to fracturing techniques (including drill/blast).  They 
basically dug big holes in situ and buried it.