1-1/2 yrs ago I had a 15'x 20' cement patio poured and also had the walk ways re-done. I live around the Chicago area. I am now noticing, after the snow melted, the top layer of the cement is flaking off in chunks revealing the stone just below the top layer (about 1/2" into the cement)this problem is rapid all over the patio and walkway. What is causing this? The man who did the work will not return our calls and I found out he never had a pour inspection done by my town. Thank you for any help you may have!