A ___ is used when forming up foundation walls to maintain form wall spacing and to hold the form wallboards together when concrete is placed.

A snap tie is indeed used in the process of forming foundation walls to ensure that the form walls are spaced correctly and secured together during the placement of concrete. The primary function of a snap tie is to provide a means to hold the two sides of the form in place while allowing for the exterior pressure of the poured concrete. Snap ties are often designed to be removed after the concrete has set, leaving a clean finish on the wall.

In contrast, a tie rod is another form of reinforcement that typically runs through the formwork; they are used for added support but are different in function from snap ties, which are more about creating the wall shape. Anchor bolts are used to secure structural elements to a foundation but do not serve the same purpose in maintaining form wall spacing. Form braces are meant for stabilizing the formwork itself during concrete placement but do not specifically hold the form boards together like snap ties do.