all concrete cracks (eventually)

concrete is its hardest at around 100 years of age

consider using Quickrete Concrete Resurfacer on your existing base to repair
it, about $25 a bag
http://www.quickrete.com/catalog/Con...esurfacer.html
the resurfacer adheres to concrete something like 3 times better than
concrete adheres to itself to itself, and due to the polymers in it, it
resists water better than concrete (water seems to be the reason for the
spalling of your base)

trowel it on, instruction on how to use concrete resurfacer
http://www.quickrete.com/diy/ResurfacingConcrete.html