shall be maintained, except the amount of water used shall be sufficient to keep only the forms or covering moist. 2. Membrane-Compound Curing: At the Contractor's option, curing compound may be used in lieu of the water-curing method. The curing compound shall be applied as soon as surface water has disappeared from concrete sur- faces, strictly in accordance with the manufacturer's direc- seal. Membrane Curing Compounds shall be similar and equal tions, in sufficient thickness to form an effective water to Horncure of the A, C, Horn Company, Long Island City, New York; Mastercure of the Master Buildings Company, Cleveland 3, Ohio; or Trucure of the Truscon Laboratories, Inc., Detroit 11, Michigan. c¢. Protection Against Mechanical Injury: crete surfaces exposed to the danger of All con- mechanical injury shall be suitably protected during construction operations. Kraft paper covering, planking and other methods shall be employed as required. If floor slabs are poured prior to roofs, particular care shall be taken to protect these slabs from injury during the roof construction operations, Floor protection methods shall be subject to the approval of the Engineer, and all damaged concrete shall be replaced or re- paired to the satisfaction of the Engineer, 5-26. molds, FORMS: Forms, complete with centering, cores, and shall be constructed to conform to the shape, form line and grade required, and shall be maintained sufficiently rigid to prevent deformation under load. a. Design: Joints shall be tight and leakproof and shall be arranged vertically or horizontally to conform to the pattern of the design. Where forms are placed in suc- cessive units for continuous surfaces, they shall be fitted to accurate alignment so that the completed surface will be smooth and free from irregularities. In long spans, where intermediate supports are not possible, the anticipated deflection in the forms due to the weight of the fresh concrete shall be accurately figured and taken into account in the design of forms, so that the finished concrete members will have true surfaces conforming accurately to the desire lines, planes and elevations. If adequate foundation for shores cannot be secured, trussed supports shall be provide Temporary openings shall be arranged in wall and column forms and where otherwise required, to facilitate cleaning and inspection. Lumber once used in forms shall have nails withdrawn, and the surfaces to be exposed to concrete care- fully cleaned before reuse. All forms shall be so construct ed that they can be removed readily without hammering or prying against the concrete, 5-17