FORMWORK AND REINFORCING IN
The steel reinforcing bars shall be in the form of round or deformed bars and shall be made by approved manufacturers in accordance with the requirements of B.S. 4449, B.S 4461 and B.S. 4483 as applicable and bent to comply with B.S. 4466. The minimum bar size to be used shall be
diameter. Welding of bars for extensions shall not be permitted. Bend tests
shall be carried out on site to cheek the quantity of rebar.
Metal reinforcement is to be secured against displacement by using N. 16 SWG annealed iron wire ties or suitable clips at inter-sections. Tails of all wire ties shall be bent away from adjacent concrete surfaces. All rebar shall be held rigidly in place so that it cannot move during concreting.
All reinforcing bars shall be stored on the site on timber supports at least
200 mm clear of the ground.
The number size form and position of all the reinforcement shall unless otherwise directed or authorized by the Engineer be strictly in accordance with the Contractor’s approved drawings. Nothing is to be allowed to interfere with the disposition of the reinforcing bars and the Contractor is to make a particular point of seeing that they are placed correctly in every respect. The minimum cover to any reinforced bar shall be at least
when below ground.
All reinforcing steel shall be free from heavy rust loose scale oil and grease or other deleterious material immediately before the concrete is placed in forms.
The Contractor must obtain the written approval of the Engineer to the reinforcement when placed before any concrete is placed.
CIVIL WORK FORMWORK
Formwork shall include all temporary moulds for forming the concrete to the required shape.
Timber forms shall be constructed of sound well seasoned timber or prefabricated steel forms may be used.
The formwork shall be fixed in perfect alignment sufficiently rigid and strong and securely braced so as to be able to withstand without appreciable displacement deflection or movement of any kind the weight of the construction and the movement of persons, materials and plant. All joints are to be grout tight to prevent leakage of liquid from the concrete, wedges and clamps are to be used wherever practicable.
All forms shall be aligned to a tolerance of ± 3mm.
Before any concreting is commenced forms and centering shall be carefully examined and the space to be occupied by the pour thoroughly cleansed out. The inside of forms shall be treated with a coating of an approved substance to prevent adhesion and the forms shall be thoroughly wetted shortly before concreting is commenced.
No concreting shall be commenced in any portion of the Works until the preparations have been approved by the Engineer.
Forms shall be removed in such a manner as will not injure the concrete and no formwork until the concrete has sufficiently set and hardened.
Damage to Concrete
The Contractor shall make good at his own expense any injury to the concrete work and any damage caused by or arising from the removal and striking of forms and supports. The attention of the Engineer must be drawn to any damage so caused and no repair work carried out without the prior approval of the Engineer.