GAIL (India) Limited

39Where necessary to maintain the tolerances indicated on the drawings. The formwork shall be camberedto compensate for anticipated deflections due to the weight and pressure of the fresh concrete, and alsodue to any other construction loads. Unless otherwise shown or specified, the camber shall be provided asbelow:-Types of memberSimple spanContinuous Restrainedspan Cantilever CantileverCamber in cms WhereK =L =D =5.5 ERECTION OF FORMWORKCompression SteelAs % of tensile steel0%50%0%50%0%50%(K X L X 2.54)/DCamber coefficientLength of member in meterDepth of member in meterCamberCo-efficient0.0660.0370.0320.0200.0860.046Forms shall be used wherever necessary to confine the concrete during vibration and to shape it to therequired line. The formwork shall conform to shapes, lines, levels and dimensions of the concrete sectionsshown on the drawings.Forms shall have sufficient strength to withstand the pressure resulting from placement and vibration ofconcrete and shall be maintained rigidly in position. Form work shall be adequately supported byadequate number and size of struts, braces, ties and props to ensure rigidity of forms during concreting.Where props rest on natural or filled up ground, to avoid any settlement, the soil shall be thoroughlycompacted and bases of props shall be sufficient size so as to restrict the bearing on the ground to 50 t/sqmForms shall be tight enough to prevent loss of mortar from the concrete and to produce dense,homogenous and uniformly coloured concrete completely free from honeycombing or surface roughness.Joints in formwork shall be designed to prevent leakage, not only between individual elements formingthe panels but also from the horizontal and vertical junction between the panels themselves.If form work is held together by bolts or wires, those shall be so fixed that no reinforcement bar isexposed on surface against which concrete is to be laid. The Consultant may at his discretion allow thecontractor to use tie bolts running through the concrete at his own cost.Hole left in the concrete by these tie-bolts shall be filled as specified by him at the Contractor’s expense.Formwork shall be constructed so as to facilitate loosening and permit removal without jarring theconcrete Wedges, clamps and bolts shall be used wherever practicable instead of nails.All formwork erected shall be approved by the Consultant/Engineer-in-charge before concreting is started.5.6 CLEANING AND OILING OF FORMSAt the time concrete is placed in the forms, the surface of the forms in contact with the concrete shall befree from encrustations of mortar, grout or other foreign materials. Temporary openings shall be left at thebottom of formwork to enable, sawdust, shavings, wire cuttings and other foreign material to be workedout form the interior of the forms before the concrete is placed.The surface of the forms to be in contact with the concrete shall be coated with an approved coating thatwill effectively prevent sticking and will not stain the concrete surfaces. After each use the surfaces offorms in contact with concrete shall be cleaned, well settled and treated with form oil approved by theConsultant Engineer-in-charge. Lubricating (machine) oils shall not be used.