Shuttering in Construction
The shuttering shall be of approved dressed timber of well seasoned wooden boards, to give a smooth and even surface and the joints shall not permit leakage of cement grout.
The timber shall be free from loose knots, projected nails, splits, adhering grout or other defects that may mar cement surface of the concrete. Opening for fan clamps and other fitting connected with services shall be provided in the shuttering as directed by Engineer-in-charge.
(i) Surface treatment for shuttering
The surface of timber shuttering that would come in contact with concrete shall be thoroughly cleaned and well wetted and coated with soap solution, raw linseed oil, or form oil of approved manufacturer, or any other approved materials such as polythene sheets, to prevent adhesion of concrete to formwork.
Suitable camber shall be provided in horizontal members of structures specially in long members to counteract the effects of deflection.
The camber for beams and slabs shall be 4mm per meter i.e, 1 in 250 and for cantilevers, at free and shall be 1/50th of the projected length or as directed by the Engineer-in-charge.
(iii) Removal of Formwork
The formwork shall be removed avoiding shock or vibration that may cause any damage to concrete. In a slab and beam constructions, side of the beam shall be stripped first; then the undersides of the slab and lastly underside of the beam.