Most common causes of concrete spalling includes:
Epoxy injection is the process of injecting epoxy resin into cracks to repair and restore the concrete back to its original state, with or without added reinforcement. The injected epoxy resin is actually stronger than the concrete and can restore the concrete strength.
Remove the spalled concrete to expose the corroded steel bars. Next, remove the rust by using a wire brush and then coat the steel bars with anti-corrosion treatment. Patched back with a non-shrink repair mortar reinforced with fibre.