Concrete can be beautiful, but what about cracks? There are few things more misunderstood about concrete than cracking. So lets talk about what’s going on with concrete and cracks. 1st is that when concrete is first poured and in its wet state it is actually bigger than after it is dried (cured and hardened), so it shrinks as it cures (dries) and over a large area there has to be some place to make up that difference in volume and that is where the first level of cracks come from. 2nd form of cracking comes from when the subsurface (supporting surface under the concrete) moves, either in soil settling or root growth etc. And the 3rd type of cracks come from over loading the design strength of the concrete and the supporting surface. The 1st type of cracks are expected and although may be an eye sore do not cause structural weakness. 2nd and 3rd type of cracks are a structural weakness. Now how to tell the difference. First place a ruler or level across the crack to see if both sides of the crack are level. If they are level the crack is not weakening the concrete. Second try and put something in the crack, if only the point of a pencil goes into the crack it is not weakening, but if the whole pencil goes in then the concrete needs repair. And now can you “fix” a crack in concrete, well yes and no. First off you can’t “glue” the two pieces back together but it can be stitched together with steel and epoxy and overlaid which is a labor intensive process, or the cracked section can be removed and replaced. I prefer the second option because it lets you check and repair the supporting surface as well. What if you just don’t like the looks of the crack but it is not structural? well there just isn’t a fix for that yet because any repair requires making the crack bigger so that you can get something into the crack and that something that is put in usually has a little different color. The crack in the picture although doesn’t look good is not structurally weakening the concrete. Adam Knoblauch Precision & Decorative Concretes