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Churting ?

by Mike Ellis
(Warsaw, Missiouri)

Q. Last year we had a large concrete patio poured, when we returned from a six month trip there are divots in the concrete exposing "white". I called the concrete contractor and he indicated that it was poor aggregates used by the concrete company. The concrete company indictaed that because the "damage" was less than five percent of total square footage, I was out of luck. The concrete company would not stand behind their product. Is this true of concrete? What is the solution or remedy

A. This is a very common problem with concrete, especially in climates with many freeze and thaw cycles. It's caused by a piece of aggregate that splits or expands which creates pressure and pops the surface of the concrete off. Once the concrete is poured there is no solution and there's not much a ready mix company can do to prevent it. The aggregates in concrete come from different places and there's no way to know whether a batch is good or not. That's why they have to protect themselves with that sq footage stipulation.

I usually use stone in my concrete mixes instead of gravel because stone causes less "popping". However, stone mixes are a little more difficult to finish and usually don't look quite as nice as gravel.

Unfortunately for you there's no much that can be done except patch the divots as they occur. Concrete is a mix of natural materials that contractors and ready mix companies have little control over. I deal with the issue all the time and if I had to go back and fix our concrete every time it "popped" then I may as well find another way to make a living.