Wednesday, September 5, 2007

Rhymes With Dynamite

I ran into lots of rock at the front of building site during the basement excavation. There was no alternative but to move it. As some of it was bedrock, it wasn't possible to dig it out; so I had to find another solution.

Enter Betonamit. Cool stuff. It works like this:

  • First you drill holes in the rock you want to break. This requires a rock drill. A rock drill is basically a 60 lb jack-hammer with a big carbide bit on it that spins as it hammers. It's powered by a big diesel powered compressor. When you turn it on you have to hang on with everything you've got because it bounces and kicks and jumps like crazy. It's great though... drills a one-and-one-half inch diameter hole 12 inches deep in solid rock in about 7 minutes.
  • Then you mix the Betonamit (it's a fine powder... looks like cement) with water and fill up the holes.
  • Now you go away and come back the next day. This stuff expands as it hardens, and exerts 12000 lbs/sq. in. pressure as it does. That's a huge amount of pressure. It cracks the rocks like eggs.

Oh yeah... it's $80 a bag, and I used three bags. Cool stuff, but expensive.

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