High Early Strength Pump Grade Underwater Repair. Five Star Structural Concrete® Underwater PG is a high early strength, single component, permanent concrete repair material designed for pumping underwater. This concrete repair material features excellent pumping properties and minimal washout during large volume placements underwater and is designed for placement in tidal zones and underwater. Five Star Structural Concrete® Underwater PG provides increased corrosion protection of steel reinforced structures with migrating corrosion inhibitor.