"Ignoramus677" wrote in message
. ..
I am confused as to what happens when concrete nails are shot into
concrete with nail shooting guns. Why don't the nails get bent? Where
does the concrete that is displaced from the hole, go? Why would the
incompressible nail hold in incompressible concrete and not fall out
of its hole?

i


The nails are heat treated, so are far more robust than are common nails.
The high speed appears to allow the nail to go where they otherwise
wouldn't, but it's not fool-proof. I use one of the simple Remington power
hammers for nailing to concrete and have had mixed results. Occasionally
you'll hit a rock that is so hard the nail won't go to prescribed depth, or
it hits nothing but soft rock or sand it will go too deep. Nailing
through an electrical knockout with a stronger charge often helps control
the depth. If nothing else, it provides a larger area for the nail head to
insure the board stays where intended.

I don't subscribe to the theory that concrete is incompressible. It has a
given amount of air space by its nature, and is rarely stronger than, say,
4,000 psi in compression, and generally not that strong. I get the idea
that the nail, driven at much higher pressure than that, easily compresses
the concrete in the proximity of the nail. When you get the desired
results, the nails hold quite well, so I can't help but think I'm on the
right track with my thinking. Do bear in mind you're talking to a high
school graduate with no mathematical training, and no engineering schooling.
It will be interesting to hear from those in the know.

Harold