dusty concrete


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Old 05-11-08, 04:26 PM
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dusty concrete

I just had a slab poured and its dusty. I mean, if I rub the surface of it with my fingers and exert a little force the solid surface gives off a bit of grit. and if I keep rubbing I can easily rub off enough that it makes a depression. should concrete do that?

...how can I lock the slab up so that If I lay tile over it,the tile will be secure and wont come loose later?
 

Last edited by mr.dave; 05-11-08 at 04:27 PM. Reason: mis-spelling
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Old 05-11-08, 06:12 PM
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Concrete needs 30 days to fully cure before you can tile or place other flooring over it. Recheck in a month and let us know if it is still unsatisfactory from your perspective.
 
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Old 05-12-08, 02:48 AM
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No, it shouldn't be dusting. Decent concrete should be set up harder than that within a day or two of pouring. There are a couple of possible causes for dusting. The first is that it was improperly poured or finished. The concrete could have been poured much too wet, or water could have been added to the surface and trowelled in to aid in finishing. This created a weak paste (with too high a water/cement ratio) that is dusting off. The same thing would happen if excess bleed water was trowelled back into the surface while finishing (overworking).
The second possible cause is that a fossil-fuel heater was used to heat the space while pouring and finishing. The carbon monoxide it released reacted with the cement paste and caused dusting as well.
Do a google search for "concrete dusting" and you will find some products that claim to stop dusting. Good luck, and follow czizzi's advice about waiting at least 30 days to let the concrete cure.
 
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Old 05-20-08, 08:43 AM
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Exclamation 30 days come and gone

thanks for the responses.
well its been over 30 days and the slab is still dusty. I remember one of the laborers doing the slab saying he felt the mixture was too wet. that said...Is there anyway to "lock" the surface so that I can tile over it, or should I repour the concrete?
 
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Old 05-20-08, 01:45 PM
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Did you google "concrete dusting" to look for products to remedy the situation? There are some that claim to.

Pecos
 
 

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