What is Reinforcement Steel
Steel bar are good in tension, while concrete are good in compression, so they are used with the concrete. When steel used with the concrete is known as reinforced concrete structure. I think now it is clear to all readers that what is Reinforcement steel and we will clear you the Measurement of Reinforcement steel later in this article.
Points to remember while Steel Reinforcement work
1. The bars shall be fabricated as per the drawings.
2. Laps and splices for reinforcement shall be as shown on the drawings.
3. The bars shall not be lapped unless the length required exceeds the maximum available lengths of bars at site or should be provided as specified in the drawing
Types of Test for TMT Reinforcement bars
Taking three samples of reinforcement bars for each lot which come to site of each diameter, getting these tested as per Indian Standards from approved laboratory (NABL verified and ISO Certified)
Types of Test for TMT Reinforcement bars include following
I Ultimate Tensile Strength
Ii Proof Strength
Iii Percentage Elongation
Iv Unit weight
V Bend / Rebend
How do you bend reinforcement bars?
a) Reinforcing bars supplied bent or in coils, shall be straightened before they are cut to size. TMT Reinforcement bars straightening of bars shall be done in cold and without damaging the bars. This is considered as a part of reinforcement bending fabricating work.
b) All bars shall be accurately bent according to the sizes and shapes shown on the detailed working drawings/bar bending schedules. They shall be bent gradually by machine or other approved means. Reinforcing bars shall not be straightened and bend in a manner that will injure the material, bars containing cracks or splits shall be rejected. They shall be bent cold, till dia of 32mm while above of over 32mm in diameter that may be bent hot. Bars bent hot shall not be heated beyond not exceeding 845 deg (not also beyond cherry red colour)
C.) and after bending shall be allowed to cool slowly without quenching. Bars incorrectly bent shall be used only if the means used for straightening and re-bending shall not injure the material. No reinforcement shall be bent when in position in the work without approval whether or not it is partially embedded in hardened concrete. Bars having kinks or bends other than those required by design shall not be used.
Fixing of TMT Reinforcement bars
Reinforcement shall be accurately fixed by any approved means and maintained in the correct position shown in the drawings by the use of block, spacers and chairs as per IS 2502 to protect the displacement during placing and compaction of concrete. Bars intended to be in contact at crossing points shall be strongly bound together at all such points with two numbers 20 gauge annealed soft iron wire or GI wire as specified in the tender.
The vertical distance required between successive layers of bar in beams or other members shall be maintained by providing of mild steel spacer bars at such intervals that the main bars do not perceptibly sag between adjacent spacer bars.
Concrete cover for Reinforcement steel| Minimum Concrete cover for TMT Reinforcement bars
Nominal cover is the depth of concrete cover to all steel reinforcement, including links. Unless indicated otherwise on the drawings, clear concrete cover for reinforcement. It should be exclusive of plaster or other decorative finish.
Minimum Concrete cover for TMT Reinforcement bars
i. At each end of reinforcing bar, not less than 25 mm or not less than twice the diameter of the bar whichever is less.
ii. For a longitudinal reinforcing bar in a column, not less than 40mm, or less than the diameter of such bar. In case of columns of minimum dimensions of 20 cm or under, whose reinforcing bars do not exceed 12 mm, a nominal cover of 25 mm may be used.
iii. For longitudinal reinforcing bars in a beam 25 mm or not less than the diameter of the bar.
iv. For tensile, compressive, shear, or other reinforcement in a slab or wall not less than 20mm or not less than the diameter of such reinforcement.
v. For footings minimum cover of shall be 50 mm. In case concrete is deposited on prepared ground surface other than PCC the cover shall be to the bottom reinforcement shall be 75 mm.
vi. For concrete surfaces exposed to the weather or the ground after removal of forms, such as retaining walls, footing sides and top etc. not less than 50 mm for bars larger than 16 mm diameter and not less than 40 mm for bars 16 mm diameter or smaller.
vii. Increased cover thickness shall be provided only when indicated on the drawings under special condition, for surfaces exposed to the action of harmful chemicals or exposed to earth contaminated by such chemical, acid, alkali, saline atmosphere, sulphurous smoke, etc.
viii. For reinforced concrete members, totally or periodically immersed in sea water or subject to sea water spray, the cover of concrete shall be 50mm more than those specified in (i) to (v) above.
ix. For liquid retaining structures the minimum cover to all steel shall be 40mm or the diameter of the main bars, whichever is greater. In the presence of sea water and soils and waters of a corrosive character the cover shall be increased by 10 mm.
x. Protection to reinforcement in case of concrete exposed to harmful surroundings may also be given by providing dense impermeable concrete with approved protective coatings.
xi. Concrete / Cement mortar cover blocks of same strength or PVC cover blocks of approved quality shall be provided to maintain the correct cover. Concrete / PVC cover blocks to be tied / fixed with reinforcement steel bars to ensure the bar remains in position. The use of pebbles or stones shall not be permitted.
Inspection Procedures of TMT Reinforcement bars
Erected and secured reinforcement shall be inspected, measured and recorded prior to placement of concrete.
Measurement of Reinforcement steel| Mode of Measurement of TMT Reinforcement bars
Lengths of reinforcement steel including spacers & chairs shall be measured to the nearest centimetre and converted to weight using IS coefficients. The actual quantity of steel embedded in concrete as calculated, irrespective of the level or the height at which the work is done shall be taken.
The unit rate for reinforcement mainly includes all wastages, binding wire, cover blocks etc. for which no separate payment are made in tender work.
Laps as shown in drawings and minimum number of chairs and spacer bars required to keep the reinforcement in position shall be measured.
Reinforcement steel shall be measured in Kgs, for the calculation of TMT Steel Bar price per kg Calculator, you visit the link attached to it.
If you have any query on the above article what is Reinforcement steel| Measurement of Reinforcement steel. Come up with your comment and if you want us to create article on Bar Bending Schedule for Reinforced Concrete, just leave your comments or connect with me – Vivek Mishra