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pitted, breaking concrete

 
 
baler
 
Reply Thu 5 Mar, 2009 03:09 pm
My newly poured concrete of 6 months is cracking and pitting. I think it's the builders responsibility to fix and repair. Is there a place to send a sample to see if it was a bad mix or something?
 
Mame
 
  3  
Reply Thu 5 Mar, 2009 04:49 pm
@baler,
I worked for several years for a civil engineer who specialized in concrete. There are several factors that could be the cause. Pitted, cracking concrete is a result of a poor mix design, as the "recipe" is called or a result of the contractors not following it correctly. Also affecting the results is the drying/curing time and the time of year (climate) it was poured. And if you live in an area where there is a lot of freeze-thaw, it is even more important that the mix design be correct and be followed.

You should consult an engineer who specializes in concrete. If you don't know one, google it in your area or consult a construction company dealing with concrete or a concrete company itself (Lafarge, for example) to find one.

Properly designed, mixed, and poured concrete should last for years. Concrete may also spall, but that is very common and doesn't affect the strength of the concrete.

It also matters what form your poured concrete is in with respect to how critical the pitting/cracking is - is it a driveway or a foundation?

Best to consult a specialist. And read your contract re: warranties, if you have one.

The engineer will take a sample to analyze it and will give you a report which you can then use to sue the ass off the guy who screwed up your concrete. He may also be able to provide you with a remedial mix to fix the problem.
farmerman
 
  2  
Reply Thu 5 Mar, 2009 05:08 pm
@Mame,
What Mame said. Concrete, if poured in winter, is usually mixed with a salt and a stabilizer (calcium chloride and a polymer) This makes it set in freezing weather , but it wont last and isnt used for tensioned concrete. ALso, "Mexican concrete" is crap concrete where Magnesium Oxide (Dolomite) is part of the "cement rock" The worst concrete is made in Mexico and VChina from High magnesian limestone . The crystals set up with "Mexican crete" is soluble and will break down within a year or so. That's what it sounds like you have. You can get a sample tested at a highway engineering lab. Look up your states DOT and find its lab HQ. They can steer you to a reputable lab. Either that or you can take a chunk of the concrete (not the part thats corroded) and take it to a University geology department and have them run an Xray diffraction analysis ior EDX analysis. If the Mag is greater than 4% , youve got Mexican concrete and the whole job is suspect.
Then Id check your contract about quality and workmanship , maybe you have a action that your insurance can help on. One year shouldnt happen unless your in a really severely acidic environment (If it was that bad, your eyes would know it and there would be a sulfitic smell in the ground)
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