What is the difference between structural and non-structural concrete repair?

Structural repair (BS EN 1504-3 Class R3 or R4) restores the load-bearing capacity of the concrete element. It uses high-strength materials and possibly additional reinforcement to ensure the structure can safely carry its design loads. Non-structural repair (Class R1 or R2) is cosmetic or protective, focusing on restoring the geometry, aesthetics, or durability of the surface without adding structural strength. For example, filling surface blowholes is non-structural, whereas injecting epoxy resin into a deep crack in a load-bearing column is structural.