Expansion Cracks

[sroxberg]

I have a pole building with a concrete floor. The building is 30 x 45 and has six 15 x 15 slabs of concrete for the floor. The slabs have expansion joints, or cuts that mark them out. These cuts are 3/16 of an inch wide and of course every small screw or part that drops on the floor finds the crack, and when I'm sweeping up sawdust you can't cross over a crack without filling it with saw dust that I then vacuum out.

So I'd like to fill the cracks with Chalk or another substance to that it is almost level with the surface, but it won't create other problems.

So any thoughts on what to use, or is this generally just a bad idea?

[Stwood_]

Steve how about maybe using some silicone based caulk?

[sroxberg]

That was my first thought and I have done some research that leads me to believe that I can/should put some backer rod in the cracks to minimize the amount of Chalk. That said if I ever painted the floor would Silicone Chalk be paintable?

[Phil Thien]

That was my first thought and I have done some research that leads me to believe that I can/should put some backer rod in the cracks to minimize the amount of Chalk. That said if I ever painted the floor would Silicone Chalk be paintable?

If you head over to the garagejournal forum, there is a flooring section there and you can find the names of products that are compatible with epoxy coatings.  I think Sikeflex was a popular recommendation.

[DaveHo]

Used this stuff in my shop & painted it.  It's been at least 5 years & the paint has not flaked off. Use backer rod for deep joints.

Loctite PL S10

[fredhargis]

I'll be doing that in a building just about the same size, and will probably just use backer rod and silicone although there is a caulking tube type stuff for outdoor concrete crack repair and I may use that.

[Roly]

Use self leveling concrete sealant, made for this use.   Normally it is polyurethane, not silicone.   Use a backer rod if the cut is deep.     Comes in a caulking type tube, both normal and large size.     Makes for a neat job.  Roly

[Mr_Mike]

Sikiflex. Its just made for this. You also need backer rod.

[AUswimKC]

For the record those are contraction joints, not expansion

Are yours sawcut or formed? Sounds like formed.

You want a polyurethane sealant. I believe sikaflex is

[Snipe Hunter]

You could grout it.