self leveling concrete issue - help needed

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Old 09-10-12, 01:10 PM
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self leveling concrete issue - help needed

i poured self leveling concrete on several areas that additions were put onto my house before i bought it ( in the 1970's they were put on) and the new slab were not level with the original. So i got some self leveling to bring them up to level. I cleaned thoroughly, primed, mixed per instruction, etc...most of the areas came out great but the two front bedrooms didn't. they where prepped and mixed the same way but after about 24 hours of drying they felt like they have air pockets completely under them. then they started cracking when pressure from walking is on them. i peeled on area up yesterday and it did not stick to the existing floor at all. I used to medium -heavy coats of primer.
what would make this not stick and have air pockets under it? all other areas are perfect.
thanks,
justin
 
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Old 09-10-12, 04:19 PM
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Was the primer a type that needs to be tacky when the topping is applied, or is it supposed to be dry? Some primers I've used can only be left untopped for 24 hours. If you primed and waited two days before applying, they might not re-wet and allow the topping to stick.
Another possibility is that the two bedrooms may have had something on the slab before (sealer? carpet glue? paint?) that was not properly removed before the primer and topping were applied.
What was the self-levelling topping and what was the primer? (brand names)
 
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Old 09-10-12, 11:11 PM
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Pecos covered pretty well all of the causes for debonding problems. The majority of overlay debonding cases I've been involved with over the years were directly related to improper surface preparation.
 
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Old 09-11-12, 09:22 AM
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the primer and SLC are the one home depot carries, i think it is Henry's brand. the primer goes on a blueish-purple and drys clear so you know when it is ready. it was on about 4 hours before add the SLC.
my only thoughts are that there is some residual adhesive on the floor that i did know about. the floors were bare when we got the house (it was a fixer upper) but in other areas of the old slab you can see adhesive from a parkay floor it looks. so now thinking about it, this adhesive is probably on the slab i am trying to level but i cannot see it. what is the best way to strip it off? do chemical strippers work well or should i get a large sanding wheel and try to scuff off the top surface?
i am open to almost anything as long as it works to prep the floor cause the SLC is expensive and i really done want to have to do this again but it looks like i will have to!
 
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Old 09-11-12, 02:12 PM
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I don't think a sander would do you much good unless you really went at it with a coarse grit for awhile. A floor grinder on the other hand would take it down relatively quickly. You'd need it to be equipped with a dust collection vac though or it would make a mess. It would remove any latence and give the floor a good profile for bonding.
Floor stripper would probably work too, although you'd have to make sure you thoroughly cleaned up all the mess and residue before proceeding with the primer/overlay. As Bridgeman said, it's all about proper prep. What does the product label recommend?
 
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