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Cement for Bay Floor Cracks
- Thread starter washregal
- Start date
Good luck. Concrete rarely cracks because it's getting old. It crcks because the ground below is shifting or washing out.. There are crack filling materials but don't expect them to fix your situation. Try www.concrete.com for ideas.
MEP001
Well-known member
How wide are the cracks? Is it just a hairline or is it wide enough for water to penetrate? Hairlines are common and not really a problem, but a larger crack can cause problems. If the cracks are wide enough to allow a filler, you might try a concrete crack filler. 3M makes several, both epoxy type and a caulk type that stays flexible.
PL makes a good concrete crack filler in a caulking gun tube. Make sure you get the stuff labeled "self leveling". It flows better and makes a nice bead that flattens out by itself. Make sure your crack is clean so it will stick to the sides of the crack. If the crack is too wide you will need a foam filler strip. It stays nice and flexible. The only problem I have had with it is trying to fill cracks that were not dry or that had loose concrete dust on the sidewalls of the crack.
Not for as bad as he said it is....If its getting worse...There is not a product thats going to help...On another note using self-leveling joint sealant..If its not perfectly level this particular product will pool at the lowest point which makes for a messy situation....
mjwalsh
6 bay SS w/laundromat
WashRegal & others,
Just to add to what Reds said ---- the urethane filler is very permanent if done right. If I remember right it is also helpful to use their special prep liquid as the first step to ensure the surface will be prepared right. You do need to dry out one area at a time to prevent downtime & let it cure enough before driving on it. The self leveling SL type tends to settle slightly below the crack which makes it so it is less likely to be torn out by tires. I hope this helps.
As far as replacing concrete --- if the cracks have caused severe heaving & unevenness then --- maybe. Our 50 year old slab part of our cement had issues with snow removal unevenness so we successfully replaced some sections ourselves after jackhammering it. In hindsight we would have rented a cement breaker for our skidsteer because the jackhammer was a little too time consuming & tough on the bod. A CAD program(autodesk) measuring volumes from uneven dimension input helped to calculate the amount of cement we had to order each time.
MJ
Thanks for the info.. I have several hairline cracks.. but also a few large divet areas.. one is like the nile river - about 6" wide x 2" deep... I need ot get something in there to at least hold it for a while.. I hear you about tearing it up and replacing.. but where I am from cash is still king.
Here is how I have repaired cracks like you described after getting instructions from my local concrete supply specialty store. I got a large concrete grinding stone from my concrete specialist that attaches to a right angle grinder. Concrete workers use these to smooth concrete or grind away high spots. In the crack you are going to repair use the grinding wheel to V the edges of the crack making the top wider. After cleaning out the crack of dirt and dust use some concrete adhesion promoter. This is typically called " Moose Milk" in the concrete trade. One brand name is Acryl 60. Use a paint brush to cover the sides of the crack with the adhesion promoter. Next get a fast drying epoxy type of cement commonly called Road Patch of fast set mortar. If you use adhesion promoter in place of the water when mixing the cement it will be much stronger when set. Working time is short ( 10 minutes) so be fast when placing it in the crack. With the fast set concrete you can have people driving on the repair in a couple of hours. BASF makes several products for this type of concrete repair. I never had much luck with the caulk gun type of repair on concrete.
MEP001
Well-known member
A 6" wide crack is certainly bad - how has that happened? Did two cracks develop close together and the whole section between drop down?
I have a thought for fixing such a big crack. When I've seen concrete guys pour new slab up against an existing one, they usually drill holes in the old concrete and insert pieces of rebar to keep things lined up. I'm thinking you could do basically the same thing, drill into the exposed concrete in the crack at the lowest angle you can, put rebar in the holes and bend it down enough so when the hole is filled with concrete the rebar is covered and preventing things from sinking further. It would be cheap if you have the tools, and hopefully permanent.
I have a thought for fixing such a big crack. When I've seen concrete guys pour new slab up against an existing one, they usually drill holes in the old concrete and insert pieces of rebar to keep things lined up. I'm thinking you could do basically the same thing, drill into the exposed concrete in the crack at the lowest angle you can, put rebar in the holes and bend it down enough so when the hole is filled with concrete the rebar is covered and preventing things from sinking further. It would be cheap if you have the tools, and hopefully permanent.
It sounds like you have very little if any rebar in your concrete. If you have floor heat it would be unwise to drill a bunch of holes in your concrete. If you ever do replace the concrete I would cut it out and pour new with plenty of rebar placed on 1 or 2 foot centers and set in the bottom 1/3 of the concrete for maximum strength.
