Spalling is caused by inadequate cover to reinforcement, which leads to corrosion.  The products of corrosion occupy more volume than the steel, thus the oxides push the concrete away.  8" square pedestals are very small for structural concrete, therefore the reinforcement has little cover.  Repair of these will likely be fruitless, resulting in repeat failures.  Suggest you rethink and replace the pedestals, doing it right this time.

Agree with hokie66...if you repair, you'll be doing it again.  If you must repair though, look at Sika Products website...they have some good info on spall repair and on corrosion mitigation.

I agree with hokie66 and Ron that for small elements, replacement is ususally more cost effective in the long run. For future reference, there is a lot of information on concrete repair techniques at the IRCI website (irci.org).