my garage sits up on concrete blocks, is yours on blocks or poured concrete?, i have several cracks at mortor joints, that i have repaired with new mortor, figured it was just from the normal settling due to season weater changes.

I am having a 24x30' garage concrete floor installed. They will be using a keyway when the slab is poured which is suppose to prevent it from cracking. Anyone know this process. Can the keyways be taken up and reused or should they be left in the concrete? How expensive are these keyways. How many should be used in this project? How far agart? The concrete supplier is closed today or else I would ask them. :-)
Of course I have to have the garage inspected before the slab is installed. Any concrete experts out there?
Thanks for your help.

ours is slab w/numerous cracks 2ndary to a huge oak tree right nearby

Toad:

In concrete work, keyways are used to structurally lock together two adjacent pieces of concrete that cannot be poured at the same time for whatever reason. The keyway form can be something as simple as a 2x4 laid down the center of a foundation footer form, to create a trough in the middle of the footer, so that when the stemwall is poured later it is "keyed" into the footer and cannot shift laterally. After the pour has cured sufficiently to hold its shape, the keyway form is removed before the second piece of concrete is poured.

Does this work include new stemwalls? If so then I can see how your contractor would want to use keyways.

Keyways are not used to control cracking in slabs. This is done in a variety of ways: control joints, expansion joints, steel matting, and fiber-reinforced concrete.