Had a garage floor poured yesterday. Weather was good about 80 degrees with no direct sunlight on the pad area. It was finished being troweled around 3:00. Within a couple of hours started noticing areas where the top paper thin layer was starting to lift. Put tarp over not on pad do to rain coming. This morning several areas are flacking off with ease leaving a ruff surface. What could be causing this problem? I’ve read that keeping it wet will slow down the curing time thus making it harder. Should I be wetting it down with this problem? I also planned on epoxing the floor- 1) how long should it cure before doing this? 2) What products would be best for this? 3) What to use to get rid of the ruff areas? Direct e-mails would be welcomed.
[email protected] Thanks, LARRY
Replies
Might have overtroweled it too smooth and bought too much water to the top
Half of good living is staying out of bad situations.
Forget the primal scream, just Roar!
I have experienced this several times over the years, and have been told that the problem is likley getting on the slab to early with the first trowling, which seals the surface, and does not allow air to escape. Since then I have been more carefull to go as long as possible before putting the first trowling machine on, and have not noticed the problem recently. This phenomenon can really make a slab look terrible after a few years when all of those loose bubbles flake off. If any one can confirm the cause of this problem, I to would be interested in hearing from those with more expertise.
Too much hurry up with the metal trowels will bring the water to the surface and make this happen. It's a job for the concrete finishers to worry about fixing - it won't be easy.
A point of clarification if I may...not trying to nitpick...still haven't poured the perfect slab...
The troweling does not bring the water to the surface.The water goes to the surface as the pad cures,and early troweling creates a thin 'skin' that traps this migrating water for a time. The water,trying to escape,pushes against this 'skin' and unbonds it from the slab, creating the situation described.
Structurally, the slab is probably fine...cosmetically?..Still looking for a solution myself.
jwwhat the heck was I thinking?
Different ways of explaining, too wet too early too bad.Excellence is its own reward!
What has happened here is that either the surface was troweled too early (the bleed water must be allowed to surface and evaporate) or someone was "baptizing" the surface with water while finishing.
When you trowel the surface you compact and seal it. If the bleed water has not already risen to the surface, it gets trapped under this top layer of cement paste and forms pockets or bubbles of water beneath the surface. Once the water is absorbed by the slab or evaporates, there is a void and delamination will start to occur.
If the slab is "baptized" during finishing it throws the water/cement ratio way out of wack and the top layer of concrete (the critical wear surface) will be weak and will delaminate. This usually doesn't occur until later after some weathering.
Sounds to me like you troweled too early in this case because the result was apparent so soon in the curing process. If I were you, I'd wait till some weathering has occured, then sandblast the entire surface and epoxy coat it then.
Eric
I think you have explained what is happening. I have one customer,(brother of my next door neighbor, and part owner of a steel fabrication company I sometimes do business with, so I cant avoid him ) for whom we replaced a driveway three years ago, and the surface went to crap. He has been hinting that he would like it fixed. The sand blasting, and epoxy solution sounds like a possible fix without replaceing the whole slab. What type of epoxy would be used? I am familure with REZI-WELD, but it would , even in its most liquid form, be to thick to spread over a driveway slab. Thanks for any suggestions.