Can it be use to repair swimming pool cracks in plaster. ?

I'm a mason. Real pool whitewash is 4 parts bar sand 1 part crushed terracotta 1 part hydrated lime and 1 part white Portland. Disregard the other mix

Yes this is what you want for pool repair. Like the previous answer says, not stand alone though. You will need sand as well and the mix is 1 part cement / 2 parts sand. You have few options on the sand, quartz or silica, marble dust, lime, etc. hope this helps.

White Portland cement is intended to be mixed with aggregates and other ingredients to make concrete, mortar, or stucco. White Portland cement should not be used alone to patch the cracks in your plaster.