Because concrete is in a semi-liquid form as it is poured, some type of structure must be in place to keep the concrete from oozing where it is not intended to go. Concrete forms serve that purpose. Offered in a variety of materials, shapes and sizes, they are manufactured for use in an extensive array of structural and architectural applications. Certain forms are intended for removal once the concrete has hardened after the pour. Others are designed to become permanent components within the finished structure. Accessories can include expansion and contraction...