(Also posted to rec.crafts.metalworking.)
I hate the crud that collects in the control joints of my shop floor.
Every so often when I get a wild hair, I open the doors and blow out the
dust/chips/invisible screws, etc with compressed air. It would be better
if the control joints were filled level with the rest of the floor.
But what's the best thing to put in there? A sealant (presumably over
backer rod)? Some kind of insert? What?
There are self leveling fillers (epoxies) that are available at some of
the local Ace, Home Despot, of masonry supply stores that cater to the
concrete trade. Pour it in, then let it settle, and harden. You can
also use concrete glue and grout mix, but I think that the epoxy is
I would say it may depend on whether the conrtol joints are trowelled (like
those usually found in concrete sidewalks) with a joint or edge trowel or if
they are saw cut. For a shop, I believe the better of the two is the saw
cut joint as these don't interfere with small wheels (like those found on
most shop equipment) and can be better sealed or filled. Either way, the
control joints are the intended places for the concrete to crack (which it
will do), although concrete doesn't always follow the "rules." So you NEVER
want to fill the joints with anything solid (hard setting epoxy, grout,
etc.) - always use a pliable substance.
I had my shop concrete pad saw cut (every ten to twelve feet) within 24
hours after it was poured nearly two years ago. So far, the only cracks to
appear are in the cuts. I have tried several things to fill the cuts to
prevent dirt for collecting there. The best solution so far (and I have
tried several) is Sikaflex Sika Contractors' Choice High Performance
Polyurethane self-leveling sealant. It is carried by Home Depots (at least
in the ones in the Phoenix, AZ area). It comes in a caulking tube for ease
in application. Although it is labelled as self-leveling, I over-fill the
joints and then use a sharpened putty knife to slice along the floor to make
the fill height match the floor height. It takes several days for the
polyurethane to cure properly, so apply the fill and go on vacation or on a
business trip because if you are like me, you will invariably step on a
sticky joint if you continue to use the shop while the filler is setting up.
If you have troweled joints, I guess you could still use the same material,
but the outcome would seem to be less satisfactory since application would
involve tapering the edges of the filler to match the contour of the joints.
I don't have any experience that would allow me to speak with wisdom in this
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