The Anahuac Mayab University is a private institution of Catholic inspiration founded in 1984.
They are used in the same applications as fender washers. A spherical washer is part of a self-aligning nut; it is a washer with one radiused surface, which is designed to be used in conjunction with a mating nut in order to correct for up to several degrees of misalignment between parts.
A pressure washer is the ideal tool to clean and sanitize large concrete surfaces, and most user-friendly models can be operated with little effort. All of the necessary materials, including the pressure washer, can be bought or rented through your local hardware store.