Concrete spalls because of a couple different reasons.
1. Air bubbles trapped in the concrete expand and contract, popping off chunks of concrete. 2. Water and salt are leaching into the concrete, building rust on the reinforcement, and breaking off concrete.
The only way to eliminate spalled concrete is to remove it, replace any reinforcing, and cast new concrete. If you have the air bubbles and pieces popping off of a concrete pad, you can identify any other delaminated sections by taking a chain and swiping it over the surface. Any pockets needed removed will create a very hollow noise - trust me you'll tell the difference. There is a newer product on the market, a latex admixture that can be added to concrete to fill the air voids in newly cast concrete to reduce leaching effects.