Expanding mortar concrete demolition

[shobroco]

Has anyone used expanding mortar for concrete demolition? I had an architect ask me about using it on a project & I'd never heard of it. His concern is noise and dust from jackhammers, not replacing explosives. I suspect that it's so expensive it's only used as a last resort when explosives can't be used.

 

[bmrossetti]

shobroco,

I've looked into non-explosive demolition agents (such as Dexpan) for previous projects, but have not actually used it yet. A 44lb. box of Dexpan will run around $100, and according to the literature will fill approximately 36 LF of 1.5" diameter holes. The manufacturer recommends a hole spacing of 12" o.c., drilled to 80% of the concrete depth. So in my case, for an 8" slab, we would get approx. 70 sf of coverage per 44 lb. box - around $1.45/sf.

Not bad for limited floor areas, isolated equipment foundations, etc. For a large floor area it could get expensive, but if noise and dust are a concern, this could be a good alternative. Bear in mind though that there will be some noise and dust regardless, as you will be drilling a grid of 1.5" diameter holes, most likely using rotary hammers. Not as bad jackhammers, but still a potential consideration.

Hope this helps,

Brandon

 

[miningman]

If you chose to go this route, try to plan on ALL holes being vertical. The stuff actually works quite well, but you need 100% filling of the holes...... very difficult to achieve in holes at less than 45 degrees. And if theres rebar in the concrte, this will severely limit the effectiveness of this technique.

 

[shobroco]

Thanks, it might actually be appropriate for the project we're looking at & not as expensive as I expected.

 

[ornerynorsk]

Hydraulic wedges are also an alternate to dexpan and crackamite, and generally much faster.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[MiketheEngineer]

You could drill a bunch of holes - fill them with water and wait for winter. It wll blow it apart - guaranteed. OH - you say you live in Florida..

Good Luck

 

[shobroco]

MTE: Actually, where I am I could use your method, but some guys get concerned about schedules & waiting around for results. Go figure!!

 

[jimodore]

OK it may be off topic and you probably have considered it and ruled it out, but what about concrete crushing jaws - I have seen good results (quietish, quick and controlled) provided access and concrete profile lend themselves to their use.

 

[shobroco]

Not so useful in a basement for a slab & foundation.