(p) At construction joints contact surface of the form sheathing for flush surfaces exposed to view shall overlap the hardened concrete in the previous placement by no less than 1 inch (25 mm). The forms shall be held against the hardened concrete to prevent offsets or loss of mortar at the construction joint so as to maintain a true surface.
(q) Wood forms for wall opening shall be constructed to facilitate loosening, if necessary to counteract swelling of the forms.
(r) Wedges used for final adjustment of the forms prior to concrete placement shall be fastened in position after the final check.
(s) FormWork shall be so anchored to shores or to other supporting surfaces or members that upward or lateral movement of any part of the formWork system during concrete placement will not occur.
(t) Runways or planks for moving labour and equipment shall be provided with struts or legs and shall be supported directly on the formWork or upon the structural member without resting on the reinforcing steel.
(u) All surfaces of forms and embedded materials shall be cleaned of any accumulated mortar or grout from previous concreting and of all other foreign material before placing fresh concrete.
(v) Forms shall be sufficiently tight to prevent leakage of grout or cement paste. Board forms having joints opened by shrinkage of the wood shall be removed and replaced. Plywood and other wood surfaces not subject to shrinkage shall be sealed against absorption of moisture from the concrete by either (1) a field applied, approved form oil or sealer, or (2) a factory applied non-absorptive liner. When forms are coated to prevent bond with concrete, it shall be done prior to placing of the reinforcing steel. Excess coating material shall not be allowed to stand in puddles in the forms nor allowed to come in contact with the concrete against which fresh concrete will be placed. Care shall be taken that such approved composition is kept out of contact with the reinforcement. Where as-cast finishes are required, materials, which will impart a stain to the concrete, shall not be applied to the form surfaces. Where the finished surface is required to be painted, the material applied to form surfaces shall be compatible with the type of paint to be used.
(w) For reinforced concrete, in no circumstances shall for until the concrete attains strength of at least twice the stress to which the concrete may be exposed at the time of striking The strength referred to shall be that of concrete using the same cement and aggregates, with the same proportions, and cured under conditions of temperature and moisture similar to those obtaining in the Work. Where possible, the formWork should be left for longer time, as it would assist the curing. In normal circumstances (generally where temperatures are above 20 0C/ (168 0F) and where ordinary cement is used, forms may be struck after expiry of the following periods.




Walls, columns and vertical sides of beams 48 hours or as may be decided by the Engineer
Side of slab (shores of props left under) 2 days
Beams soffits (shores or props left under) 12 days
Removal of shores or props to slabs:
Spanning up to 13 ft. (4 meter)
Spanning over 13 ft. (4 meter)
12 days or as approved
16 days by the Engineer
Removal of shores or props to beams
Spanning up to 20 ft. (6 meter)
Spanning over 20 ft. (6 meter)
18 days or as approved
25 days by the Engineer

For rapid hardening cement 3/7 of the above period will be sufficient in all cases except vertical sides of slabs, beams and columns which should be retained for a minimum of 24 hours.

The number of shores or props, their sizes and disposition shall be such as to be able to safely carry the full dead load of the slab and beams, as the case may be.

Proper allowance shall be made for the decrease in rate of hardening of concrete in cold weather and the above minimum duration must be increased when the mean daily temperature is below 20 degree C.

(x) When repair of surface defects or finishing is required at early age, forms shall be removed as soon as the concrete has hardened sufficiently to resist damage from removal operation
(y) Top forms on sloping surfaces of concrete shall be removed as soon as the concrete has attained sufficient stiffness to prevent sagging. Any needed repairs or treatment required on such sloping surfaces shall be performed at once and be followed by the specified curing.
(z) Wood forms for wall openings shall be loosened as soon as this can be accomplished without damage to the concrete.
(aa) All formWork shall he removed without such shock or vibration as would damage the reinforced concrete. Before the top plank and struts are removed, the concrete surface shall be exposed where necessary in order to ascertain that the concrete has sufficiently hardened. Proper precautions shall be taken to allow for the decrease in the rate of hardening that occurs with all cement in the cold weather.
(bb) When restoring or repropping is permitted or required, the operations shall be planned in advance and shall be subject to approval. While reshoring is underway no live load shall be permitted on the new construction

In no case during reshoring shall concrete in beam, slab, columns or any other structural member be subjected to combined dead and construction loads in excess of the load permitted by the Engineer for the developed concrete strength at the time of reshoring.

Reshores shall be placed as soon as practicable after stripping operations are complete but in no case later than the end of Working day on which stripping occurs.

Reshores shall be tightened to carry their required loads without overstressing the construction. Reshores shall remain in place at least until tests representative of the concrete being supported have reached the strength specified sub-Clause 5.23 hereof.

(cc) Floors supporting props or shores under newly placed concrete shall have their original supporting props or shores left in place or shall be reshored. The reshoring system shall have a capacity sufficient to resist the anticipated loads and in all cases shall have a capacity equal to at least one half the capacity of the shoring system above. The reshores shall be located directly under a shore position above unless other locations are permitted.

The reshoring or re-propping shall extend over a sufficient number of stories to distribute the weight of newly place concrete and construction live loads in such a manner that the design superimposed loads of the floors supporting shores or props are not exceeded.

(dd) It is generally desirable to give forms for reinforced concrete an upward camber to ensure that the beams or slabs (specially cantilever slabs) do not have a sag when they have taken up their deflection, but this should not be done unless permitted by the Engineer.
(ee) No loads, other than man and light plant required in connection with the actual Work in hand, shall be allowed on suspended floors until 28 days after concreting where ordinary Portland Cement is used and 14 days when rapid hardening Portland Cement is used.