We recently poured a cement pad for a workshop addition. When we removed the forms, we noticed that in some places the cement had significant areas where there was more gravel and air than cement. That is, the cement ahd not completely filled in around the gravel leaving a cottage cheese look to it.
The cement truck was a new fangled type that mixes at pour time (no big spinning barrel.) When the cement truck was pouring the cement we noticed that at some points the consistancy of the cement was mostly what seemed like rock with relatively little actual cement, and was very tough to screed. We figured the cement guy knew what he was doing so we didn't say anything. Besides it all looked fine on the surface after running the float over it.
Is this pad likely to develop problems? Is it safe to build on?
I took some pictures with a digital camera. Take a look: