Stripping. 3.8.1. The engineer-in-charge shall be informed in advance by the contractor of his intention to strike the form work. While fixing the time for removal of form, due consideration shall be given to local conditions, character of the structure, the weather and other conditions that influence the setting of concrete and of the materials used in the mix. In normal circumstances (generally where temperatures are above 200C) and where ordinary concrete is used, forms may be struck after expiry of periods specified below for respective item of work. In normal circumstances and where ordinary cement is used forms may be struck after expiry of following periods: a) Side of walls, columns and vertical faces of beams - 24 to 48 hours b) Beam softish (props. left under) - 7 days c) Removal of props slabs: i) Slabs spanning upto 4.5 m - 7 days ii) Spanning over 4.5 m - 14 days d) Removal of props for beams and arches i) Spanning upto 6 m - 14 days ii) Spanning over 6 m - 21 days
3.8.2. All form work shall be removed without causing any shock or vibration as would damage the concrete. Before the soffit and struts and struts are removed, the concrete surface shall be gradually exposed, where necessary in order to ascertain that concrete has sufficiently hardened. Centering shall be gradually and uniformly lowered in such a manner as to permit the concrete to take stresses due to its own weight uniformly and gradually. Where internal metal ties are permitted, they or their removable parts shall be extracted without causing any damage to the concrete and remaining holes filled with mortar. No permanently embedded metal part shall have less 25 mm cover to the finished concrete surface. Where it is intended to re-use the form work, it shall be cleaned and made good to the satisfaction of the engineer-in-charge. After removal of work and shuttering, the Addl. City Engineer shall inspect the work and satisfy by random checks that concrete produced is of good quality.
3.8.3. Immediately after the removal of forms, all exposed bolts etc. passing through the cement concrete member and used for shuttering or any other purpose shall be cut inside the cement concrete member to a depth of at least 25 m below the surface of the concrete and the resulting holes be filled by cement mortar. All fins cussed by form joints, all cavities produced by the removal of form ties and all other holes and depressions, honeycomb spots, broken edges or corners and other defects, shall be thoroughly ...
