REINFORCEMENT STEEL
SUPPLY :
Steel Reinforcement for concrete shall be round / ribbed bars, unless otherwise specified and shall comply with the following grades.
High strength deformed steel bars conforming to IS : 1786. If specified, tested quality high yield strength deformed corrosion resistant steel (CRS) bars from TATA (TISCON – 50 CRS) or SAIL (HCR – REBARS Gr. M) conforming to IS : 1786 for mechanical properties with improved corrosion resistance and bond strength shall be used.
All steel shall be procured from original procedures. No re – rolled steel shall be incorporated in the work. Only new steel shall be delivered to the site and shall be free of mill scale, loose rust, grease oil, paint or any other deleterious materials which reduce or destroys bond.
MEASUREMENT OF REINFORCEMENT
Measurement relating to nominal mass, dimensions and tolerances of various types steel shall conform to relevant IS codes.
Reinforcement shall be measured in lengths of bar as actually placed in position on standard weight basis, no allowance being made in the weight for rolling margin.
Wastage, chairs and binding wire shall not be measured. Authorized overlaps and splices shall only be measured. Rate quoted shall include the cost of welding if specified.
TESTING :
Test certificates from manufacturer, mill certificates and certificates of origin shall be submitted for each consignment. Additional tests if required shall be done as recommended by the client / consultant at the contractor’s own cost. An accredited laboratory shall carry out testing. Any reinforcement so sampled and tested which fails to comply with the specifications shall be rejected and the whole batch shall be removed from the site immediately. The contractor shall have no claim for bars mutilated in obtaining test samples.
SAMPLING
Sampling shall be done in accordance with relevant IS : codes. For every
40 tonnes of steel at least one test shall be done.
CRS reinforcing bars shall conform to the physical properties of IS : 1786. In addition when tested for corrosion resistance as per the standard ASTM method such as salt spray test (B. 117.90), Potentio Dynamic Polarization measurement test (G5. 78), Atmospheric Corosion test G.50.76) and Sulphur-di-oxide chamber test (G.87.84) shall exhibit corrosion resistance index of minimum 1.5 CRS (deformed) bars should either be butt or lap welded as per recommended practice of IS : 9417. For best results basic coated electrodes containing copper and / or nickel shall be used.
The chemistry of CRS should be given below :
Carbon- 0.15% max
Sulphur (S)- 0.05% max
Phosphorus (P)- 0.12% max
S + P- 0.17% max
Silicon- 0.45% max
Corrosion
Resistant elements - 0.15% max
BINDING WIRE :
The reinforcement shall be securely bound wherever bars intersect or wherever required with 16 or 18 gauge (1.63 mm or 1.22 mm) annealed steel wire conforming to IS : 280.
MECHANICAL SPLICES :
Mechanical connections for splicing reinforcement bars in congested locations shall be used only with the approval of consultant / Engineer – in – charge. Patented couples as manufactured by Usha Martin Industries Ltd., (CCL bar grips) and BBR India Ltd., attached to the reinforcement bars by forging, hydraulic pressing or screw couplers in special circumstances may be permitted. All operations relating to reinforcement coupling shall be done using supplier’s patented machine / equipment and in the presence of the supplier’s representative. The contractor shall submit relevant trade literature, mil certificates, certificate of origin and letters of approval for each proposed application. A sample of each type of mechanical coupler shall be submitted for testing and approval prior to the use of any coupler in the works.
WELDING ELECTRODES :
Electrodes used for welding of steel bars shall be ordinary mild steel grade 2 electrodes conforming to IS : 814 and shall be the best quality and approved by the Engineer – In – Charge. The work shall be carried out as strictly as per IS : 2571 and IS : 9417.
CAUSES OF REJECTION :
Steel reinforcement, not conforming to relevant specifications, shall be rejected by the client / consultant. Every bar shall be inspected before assembling on the work and defective, brittle or burnt bar shall be rejected. Cracked ends of bars shall be discarded. The contractor at his own expense shall immediately remove rejected steel from the work site.
STORAGE :
Steel reinforcement shall be handled and stored in a manner that bending or distortion of the bars is avoided and corrosion of steel is prevented. They shall be stored in such a manner that they are not in direct contact with the ground (at least 150 mm clear above ground). In case of long storage, a coat of cement wash shall be given to the reinforcing steel to prevent any scaling or rusting. Any reinforcement which is certified as corroded by the Engineer – In – Charge, shall either be immediately withdrawn from side or stand blasted and coated with cement slurry. No extra payment shall be made for sand blasting and cement coating. Bars of different classifications and size shall be stored separately. Generally, storage of reinforcements shall be in accordance with clause 3.7 of IS : 4032.