CS-45-48 Douglas Fir Plywood, and shall be EXT-DFPA- CONCRETE FORM grade not less tnan 5-ply and at least 9/16 inch thick. 3. Form Lining: of the following: (a) Form linings shall be one. Plywood: Plywood for form lining shall conform to the requirements of the U. 5. Commercial Standard CS-45-48 Douglas Fir Plywood, and shall be EXTDFPA-CONCRETE FORM grade, 3 ply, not less than 1/4 inch thick. (ob) Fiber-Board: Fiber-board for form lining shall conform to the requirements of Federal Specification LLL-F-311, Class B, not less than 3/16 inch thick. 4, Metal Forms: Metal forms shall be of a type approved by the Engineer that will produce surfaces equal to those specified for wood forms. 5. mineral oil. 6. Form Oil: Form oil shall be a nomstaining Form Ties: Form ties shall be of a design approved by the Engineer. Ties shall be adjutable in length and free of devices which will leave a hole or depression back of the exposed surface of the concrete larger than 7/8 inch in diameter. Ties shall be such that when forms are removed, no. metal shall be within one inch of the finished surface. gHardeners and Dustproofers: Hardeners and dustproofing materlal shall be a colorless aqueous solution of zine or magnesium fluosilicate. Each gallon of the solution shall contain not less than 2 pounds of the crystals. <A proprietary hardener approved by the Engineer may be used provided the hardener is delivered ready for use in the manufacturer's original containers. h. Reinforcement Bars: Reinforcement bars for concrete shall conform to the requirements of A.S.T.M. Designation A-15-39. Types and grades of steel for specific purposes shall be as specified below" 1. Tiles and Stirrups: Ties and Stirrups shall conform to A.S.T.M. Designation A-15-39 for billet steel bars, deformed class intermediate grade. 5-4