concrete topping cracks

[dbriant]

We have started a preliminary investigation into an existing concrete slab structure from the 1950's. I'm not sure of what the framing system is. The owner is concerned about continuous cracking of the slab in what is described as an alligator pattern. It appears that there is a concrete base slab (about 6 inches thick), coated with ironite and topped with about 2 1/2" of concrete. The cracking is only in the concrete topping and is aggressive enough to pop it loose in spots. Some areas have been patched and are popping loose again.

My presumption is that the expansive property of the ironite is what may be causing the topping to pop loose. Any thoughts on how to neutralize this other than grinding it off and replacing the topping?

 

[Ron]

None. Remove the topping. Sounds like it probably had too much water in it when placed.