Work procedure for laying and fixing reinforcement steel bars

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GENERAL INSTRUCTIONS

• Start reinforcement works with proper “Good for Construction” drawings and general specifications as issued by the consultant.
• Make a stage-wise BBS (Bar Bending schedule) on the computer before indenting for steel.
• IS codes such as IS 456, IS 1786, IS 2502, SP 34 should be available at site office at any given time for ready reference.
• Earmark the reinforcement work yard and stack yard. Care should be taken to ensure accessibility for trailers and availability of sufficient working space.
• In case of extreme site constraints, the cutting and bending can be done elsewhere and transported to site.

MATERIALS
Mild steel bar should comply with IS 432.
Cold worked steel high strength deformed bars should comply with IS 1786.

• Steel weighment should be done at site by the storekeeper by taking it to the nearest weigh bridge.
• Stack steel 300 mm clear of ground on SSM walls.
• Stack steel - Grade wise, consignment wise, diameter wise and length wise.
• Protect stored steel from rusting, oil, grease and distortion.
• Ensure Mill Certificate is delivered with each load.
• Binding wire shall be 16 - gauge soft annealed iron wire or 18 gauge GI annealed wire.
• Collect the rings used for bundling rods in bags and store them.
• Cut pieces/ scrap should be stored separately in an enclosed area with dunned.
• If steel is going to be exposed to weather for a long time, give cement wash to protect it from corrosion.
• Surface rusting is good as it ensures proper bonding and should not be a cause of worry.
• Steel is tested for its chemical and physical properties. Chemical tests check for the Carbon, Sulphur and Phosphorous content, while the physical tests check the Ultimate tensile strength, Elongation, Bend and Re-bend test.
• Test frequency should be as per ISO procedure manual.

CUTTING BENDING AND PLACING REINFORCEMENT

• Cut the rods economically to reduce wastage as per the BBS. Start laying rods only after shuttering is totally cleaned and oiled and checked for levels etc.
• Pitted, deformed, defective, corroded, cracks; splits on bend bars should not be used and rejected, removed from site.
• Neither the size nor length of the bars should vary with respect to drawings.
• Tolerance for cutting of reinforcement = +75 or -25mm
• Bending Tolerance = +0 or -10mm
• Bar spacing = + or -10mm
• Take extreme care while bending steel already cast partially in concrete so as not to damage the concrete around the bars.
• All laps should be 50d or as specified.
• Laps are staggered and not more than 33% of bars shall be lapped in a particular section.
• Mechanical splicing and welding of rods should be done only after proper details and instructions are available from the structural consultant.
• At time of concreting, reinforcement shall be free from mud, oil, grease, mortar dropping, mill scale or other foreign matter.
• Give spacer blocks in CM 1:2 and cured for at least 7 days immersed in water.
• Give spacers as per specifications. Generally 15mm for slab, 25mm for beam and 40mm for the footing is provided. It depends on the maximum size of aggregate, the reinforcement size and the element concreted.
• Proper end bearing of rods with required development length are the main points to check.
• Chairs should be placed as last operation before concreting to avoid distortion of top rod due to traffic.
• Check if dowels for columns, beams and slabs are given correctly and is of required minimum length.
• For slab reinforcement, the structural consultant should check and certify each work before concreting.
• Highlight areas of reinforcement congestion and get the bar arrangement revised to facilitate easy flow of concrete all around.
• Spacer bars shall maintain vertical distance between successive layers of bars.
• Binding wire ends after tying should be turned inside and should not stick out to the surface.
• Work should be neat, correct as per drawing and specification. A separate engineer with prior experience in reinforcement works is required to supervise works.

TOOLS TO BE USED BY TRADESMEN
Required tools must be available at site to ensure correct work. Basic tools of the reinforcement gang are:
1. Binding wire
2. Twisters and tongs
3. Long handle Steel cutters
4. Crowbar
5. Measurement Tape
6. Levers of varying sizes
7. Marking stick and chalk
8. Chipping tools
9. Hammer

INSPECTION METHODOLOGY FOR QUALITY ASSURANCE
1. Steel Mill Certificate is delivered with each load
2. Adherence to reinforcement detail as per drawings in
Sunken areas
Inverted Beams
Columns
3. Cover blocks for the above
4. Check overlapping wherever possible
5. Check Binding wires – whether joints are properly bound
6. Check for chairs and their disturbance due to movement of labour
7. Columns to be checked for plumb. Check for plumb by holding the spirit level to the formwork at various points.
8. Protruding reinforcement in the balcony and other areas to be checked for parallelism using spirit levels before and after concreting. Supports need to be checked.
9. Dowels to be checked for adequate number and strength. Wherever walkways, or staircases or balconies are connected, dowels to be inspected by the structural consultant before concreting.

TOOLS TO BE USED FOR QUALITY INSPECTION
1. Plumb bob
2. Spirit levels = 1.5m to 2m levels
3. Measuring tape
4. Screw gauge
5. Related “Good for Construction” drawings