If your terracotta floor is getting flaky or has white stains, it was probably damaged by saline efflorescence due to rising moisture. This is common with outdoor flooring where humidity, due to the absorption of rainwater or a poorly insulated substrate, carries salt dissolved in the water to the surface, where it becomes insoluble upon contact with the air.
To clean efflorescence, use DETERDEK Grout Haze Remover diluted 1:5, then rinse. If the phenomenon occurs frequently, you can apply HYDROREP ECO Water Repellent Sealer.