On flatwork (slabs), spalling can be caused by working the surface too early after pouring, thus bringing up too much of the fines, which when curing, shrink at a different rate than the underlying mix.
__________________
If you don't have time to do it right the first time, when are you going to have time to do it over?
Another common cause is when the surface get dry during finishing work and the concrete contractor decides to add cement and water to form a paste for working the surface during finishing. This is actually a common trick many contractors will try, and it never works. It is a temporary bandaid to solve the contractors immediate concerns at hand. It can also cause discoloration in the surface.
Spalling in Concrete
Re: spalling in concrete
