REINFORCED CEMENT CONCRETE – TYPES, USES, ADVANTAGES, RCC

REINFORCEMENT IN CEMENT CONCRETE

• Mild steel bars C.T.D. (Cold Twisted Deformed) 
• High yield stress deformed bars (H.Y.S.D.)

1. The pitch length between the twist should be 8 to 12 times that of the nominal diameter of the bar.
2. The diameter of the bar should not vary. For measuring the diameter of bars, a Screw Gauge or Vernier Caliper should be kept on site.
3. Steel should not be brittle in nature but soft for working. It should not break into pieces during bending.
4. The length of the bar should be between 11 to 12 meters.
5. Steel should not be corroded. This can be checked by the rusting layer on bars and by taking the weight of the steel bar before and after immersion in water for 24 hours. The loss of the weight of steel shows the depth of corrosion.
6. In the case of TOR’ steel TOR,’ a mark should be present on each meter length.

• The binding wire should be of 16. gauge.
• It should be soft in working and should not be brittle.
• When tied, it should not loosen from its position.
• It should not be corroded.

The approximate theoretical weight of the steel bar in kg meter should be calculated as (d2 ÷ 162), where ‘d’ is the diameter of the bar in mm.

3. STACKING OF THE STEEL

1. Stack in the steelyard only.
2. Bars should not touch the ground to avoid rusting of bars.
3. Spread shingle in the steelyard to prevent direct contact of soil with steel bars to avoid rusting.
4. Stack diameter-wise.
5. Steel stack should be on reinforced cement concrete blocks at a height of at least 30cm (l’.0″) above ground level.
6. Separate space should be kept for cut pieces.
7. G.I. sheet steelyard should protect from subsoil water, all around by putting murum soil on all four sides.
8. Separate space should be provided in the steelyard for ready beams, rings, etc.
9. Proper access for truck movement should be provided from the main road to the steelyard.

BENEFITS OF A STEEL YARD

1. It allows sufficient space to stack steel of different diameters separately.
2. Sufficient space to R.C.C. fitters for working outside the steelyard.
3. Controls the possible thefts of small steel pieces as the working of the fitter is inside the steelyard.
4. Controls any wastage by the fitters.
5. Full utilization of ‘rejas’ (small cut pieces) in beams, slabs, lintels, lofts, etc.
6. Locking arrangements can be made for individual stacks to prevent theft and check that the fitters utilize available ‘rejas’ before taking new steel.
7. Overall security can be maintained by locking the main gate.

4. BAR BENDING SCHEDULE

(a) NECESSITY OF BAR BENDING SCHEDULE

Bar bending schedules help the site engineer and R.C.C. fitters to give the exact cutting length of steel, required for each member, i.e., beam, slab, column, etc. This reduces the wastage of steel. With the help of a bar bending schedule, the site engineer can calculate the exact quantity of steel required for slabs and beams. A counter-check on quantities, calculated by the site engineer is also easy.

when it is accompanied by the bar bending schedule. R.C.C. fitter gets familiar with the bar cuttings and bent-up bar lengths before cutting of steel and mistakes in bending can be avoided. Bar bending schedules also help in checking the slab reinforcement. With rapid increases in the cost of steel, cost-effectiveness during construction can be maintained with the use of a bar bending schedule. Every kilogram of extra steel used is a national waste and can be avoided with the help of bar bending schedules.

1. Cutting should be done for the footing mesh (jali) bars considering the allowance for ‘L’ and covers on all the sides.
2. Footing jail should be prepared by tying the bars. Care should be taken to tie each and every junction with a binding wire.
3. Cut the column bars to the required length considering the allowance for base ‘L’.
4. Cut the bars for column rings, single or double, as per the requirement of the length accordingly. 
5. Rings should be prepared on the fitters’ platform, considering the width and breadth of the column and deduct the cover from the same, e.g. for a column of 150mm width and 300mm breadth, the ring can be of size 100mm x 250mm, considering 25mm cover on both faces.
6. Footing jali should be kept in the footing shuttering with a column base tied to its center, with binding wire. The center of the footing should be matched with the jali of the footing.
7. The proper cover should be maintained from the sides as well as from the bottom.

1. Consider floor-to-floor height and lap length 45D to be added into the length. (D is the diameter of the bar).
2. Cutting should be done first for the main reinforcement.
3. Cut the bars for rings of the column, to the required length as explained earlier.
4. For lapping, make the joggle if the bar diameter is more than 12 mm.
5. Prepare the column on the fitters’ platform by tying the rings to the main reinforcement, if the size & No. of bars are not heavier.
6. Shift the column to the slab and erect it in the required position and tie it to the dowels below the floor columns.
7. Care should be taken to tie the dowels of the below-floor columns firmly, to the upper-floor columns.

1. In R.C.C. drawings, the number of bottom bars, bent-up bars, and top bars along with details of rings is normally mentioned.
2. Fitters generally take the actual measurements of the beam after shuttering and then proceed for the cutting of the steel.
3. Cutting should be done beam-wise & for the total number of beams, required for the slab.
4. Tie a chit of paper for easy identification, to the bunch of bars.
5. Then cutting of the rings should be done. Rings should be prepared out of these cut bars.
6. The beam can be bound on the fitter’s platform along with the bent-up bars.
7. Shift the bound beams to the shuttering of the slab.
8. Place these beams to the position with proper anchorage in the end columns.
9. For continuous beams, bent-up bars should be properly extended in the adjacent beams and tied with binding wire.
10. The proper cover should be provided to the bottom and sides of the reinforcement.

(d) PROCEDURE FOR SLAB REINFORCEMENT

1. Take the measurement of the cutting length of the slab reinforcement and accordingly the cutting can be done.
2. For continuous slabs, consider the projection of the bent-up bars in the adjacent slab while calculating the cutting lengths of the slabs.
3. The cut bars should be stored in bunches slab-wise and can be transferred on the slabs accordingly.
4. Marking for the c/c distance of the bars should be done on the slab plates with the help of chalk.
5. Lay the main reinforcement as per the marking.
6. Place the distribution steel on the main reinforcement and every junction should be tied with binding wire.
7. Bent-up bars should be bent at the required length from support as per the type of slab, i.e. continuous or simply supported, etc.
8. Place the chairs under every bent-up bar to maintain the top reinforcement at the top.
9. Bent-up should be lifted considering the slab cover and slab thickness.
10. All hidden beams should be placed such that the center of the hidden beam should be considered the center of the proposed wall on that beam.
11. The ring of the hidden beam should be bound such that it is just 1″ (25mm) less than the thickness of the slab. e.g. for 5″ (125mm) thick slab, the ring for H.B. should be 4″ (100mm) in height.

1. For the water tank, reinforcement of the bottom slab, along with the beams, should be placed and bound properly.
2. Through this slab reinforcement of vertical pardi (R.C.C. thin wall) should be taken with necessary anchorage. Vertical bars of the pardi are normally erected first.
3. Provide Chamber bars at the corner as per the design.
4. Generally, double jali is provided to the bottom slab.
5. After the casting of the bottom slab, horizontal reinforcement of the vertical pardi should be bound with due care, on anchorage inside the pardi.
6. Provide horizontal reinforcement at both the faces of Pardi. Ensure a proper cover to this reinforcement. Side chamber bars to be provided as per the specified spacing.
7. After casting off the side Pardi, the formwork of the top slab should be bound as per the design.
8. Provide a manhole for the top slab along with a vent pipe hole. For the manhole, extra bars should be provided along the periphery of the opening.
9. If cut pieces are to be used for the top slab, the lap length of the same should be 69D, where D is the diameter of the bar. Care should be taken to provide laps in a staggered manner.

1. For chajjas and cantilever slabs, the main reinforcement should be provided at the top of the slab.
2. Every alternate bar or as specified by the R.C.C. designer should be bent back at the bottom.
3. The anchorage of the top reinforcement should be provided either in the beam, adjacent slab, or column, as the case may be.
4. For beams and lintels, the reinforcement should be anchored around the beam with the required anchorage.
5. For slabs, the reinforcement should be continued in the adjacent panels for the required anchorage length.
6. The anchorage length should be a minimum 69D or the span of the cantilever, whichever is more.
7. Chairs should be provided below every bar of the slab, to keep the top reinforcement in position.
8. Distribution bais should be provided as per the required spacing.

• The spacing of bars differs.
• Each alternate junction of bars is tied with binding wire.
• The column base is not tied to the footing jali properly.
• Column main corner bars are not laid in a 45° position with the plan.

• Stirrups for main reinforcement are not bound to each bar.
• Spacing between the stirrups is found to be unequal.
• The main reinforcing bars and stirrups are not tied tightly to each other.

1. The top bars of beams are not bent in 90 degrees. The distance of bent-up from the face of the support differs.
2. The spacing of stirrups differs with the specified drawings.
3. For the end support of beam, bent-up bars are not bent into the beam or column up to the required depth.
4. For 150mm wide beams, the pin is not provided to the bottom bars when the number of bars exceeds two.
5. Side face reinforcement is not provided to the beams having a depth of more than 750mm.
6. Beam bars are not passing through column reinforcement.
7. The full bearing of beam bars is not given on the column.
8. The angle of 45° is not maintained for a bent-up bar in a beam.

1. The spacing of the main reinforcement.
2. A distance of bent up from the face of the support differs from typical bar bending.
3. Every junction of the main and distribution bars is not tied to each other properly.
4. For the end support of the slab, bent-up bars are not bent or hooked into the beam.
5. Insufficient chairs are provided under the bent-up bars.
6. Laps for slabs are not provided in a staggered manner.
7. The lap lengths provided are insufficient.
8. The length of the projection of bent-up bars, in the case of the continuous slab, is not found as per the requirement, i.e., L/4.
9. The height of the bent-up bars is always found to be the same for different thicknesses of slabs.
10. The extra length of cutting bars at the ends leads to an improper end cover.
11. Insufficient chairs are provided to cantilever slabs, due to which top reinforcement is not properly maintained at the top position.
12. Same lap length for all diameters of bars.

1. Do not cast: he s.ab before checking is done by the concerned higher authorities.
2. The checklist should be written by J.E. & checked by the concerned higher authorities.
3. Send one copy of the checklist to the head office after the necessary checking.
4. Refer to the checklist as a guideline for checking work.

1. Sieve analysis of the sand and metal should be carried out to decide the volumetric mix design.
2. According to the importance of the structural member, the method of mixing, i.e., volumetric by weight should be decided.
3. Levels of the slabs and their dimensions should be checked, well in advance.
4. Slabs should be checked by the architect and R.C.C. consultants for the correctness of dimensions and reinforcement.
5. The concealed electric conduit work should be checked for its quality as per the requirements.
6. Arrangements for water and standby arrangements for the same should be made.
7. A sufficient number of laborers should be present for concreting.
8. The contractor should be informed of the time of commencing the slab and the maximum time allowed for slab casting, well in advance.
9. Decide the position of the reinforced cement concrete joints for a large slab with the prior consent of the R.C.C. consultant.
10. Check all the machines for proper operation.
11. Check the availability of fuel for the machines such as mixers, vibrators, lifts, etc.
12. Check whether a sufficient number of measuring boxes (farmers) are ready or not.
13. Check a sufficient number of cube moulds for casting the cubes for checking.
14. Ensure the removal of wooden pieces, papers, dust, etc. from the slab and beam before casting.
15. Check the arrangement of planks and M.S. walkways over the slab, for easy labour movement; without disturbing concrete & reinforcement.
16. Ensure sufficient light arrangement for late-night concreting.
17. Ensure for the arrangement of staff & allot their duties.

• Check that all the fan hook boxes are placed in position.
• Check whether the vibrator is properly placed over the stand for use during concreting.
• Ensure that one supervisor is present near the mixer for checking proper mixing and the correct quantity of water for mixing the concrete. This supervisor should maintain the register batch-wise and control the proportion of the ingredients. The slump cone & cube moulds must be available with the supervisor.
• Check whether the M.S. platform is placed over the slab, for delivery of the reinforced cement concrete on the platform.
• Buttering of the mixer should be done before starting the regular slab work.
• Quality and consistency of the concrete mix is checked for the first batch and alterations, if any, should be made in the mix proportion as per the ingredients available.
• Care should be taken first to cast the beams and compact layer-wise with the help of the vibrator. Though the vibrator is applied to beams, reinforced cement concrete should be also compacted manually with the help of tamping rods.

1. For the initial batch, the slump test should be carried out to find out the consistency and workability of the concrete mix. The alterations in the proportion of ingredients should be made if the mix is not consistent and workable.
2. “Beams first and then slabs’: This method should be applied for concreting.
3. Ensure the proper level of the slab after finishing by the mason, by visual inspection.
4. Ensure proper thickness and finishing of staircase steps and waste slab.
5. Do not allow anyone to walk over fresh and finished concrete.
6. Ensure the presence of a carpenter below the slab shuttering, during casting, is in progress.
7. Ensure a proper bottom and side cover for slabs and beams at every stage of concrete.
8. Ensure a proper finish to the slab panel, where the lift delivers the concrete.
9. For concreting in hot weather conditions, cover the fresh slab by wet gunny bags, to prevent drying of the top surface of the reinforced cement concrete.
10. In case of rain, cover the slab with a big plastic turpentine sheet to protect it.

Bar bending schedule for beam – click here for download

Bar bending schedule for the column – click here for download

Bar bending schedule for slab – click here for download

Bar bending schedule for footing – click here for download

1. Why concrete is used in RCC?

Reinforced Cement Concrete is a combination of concrete and steel to build good structures instead of using only concrete. Its life 100 years or more than, not any effect taking high temperature.

2. What are the types of reinforced concrete?

Glass Fiber Reinforced Concrete (GFRC)

Steel Fiber Reinforced Concrete (SFRC)

Natural fiber reinforced concrete (NFRC)

Polypropylene Fiber Reinforced concrete (PFR)

3. How many kg of steel is required in 1m3 of concrete?

Generally, 100-125 kg stell required 1m3 concrete.

4. Why steel is used in RCC?

When steel mix with concrete its life is 100 years & stell can stand high temperatures. & it’s very flexible.