| Sat Aug 29, 2015 | Total posts : 5 |
| bala |  | | Join date: Jul 2014 |
|  Topic: Laping length requirement
Dear friends,This is regarding the lapping requirement. We are doing construction work in the first floor . So for raising the pillar we need to have lapping of steel . So how much lapping length to be made . As per some searching we are telling that 5 times of thickness for length (as minimum 50 *16 mm= 800 mm = 80 cm )
But contractors saying as per their experience min 50 cm
Please suggest your view
Thanks
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| Mon Aug 31, 2015 | Post #1 | S L Gupta (Civil Engg)
Join date: Mar 2008 | Dear Bala
There
should be no joints in steel bars used for RCC work. If it is necessary
to use small length steel bars, proper overlap should be given.
The joints of bars should be welded in case the diameter of
bars is more than 36 mm. Overlapping of bars should not touch each other
and they should be kept apart. Where it is not possible, overlapping
bars should be bound together at intervals not exceeding twice the
diameter of such bars with two strands of steel wires trusted tight. The
overlap should be staggered for different bars. The length of overlap
should not be less than 50 times the diameter of steel bar.
2) Precautions while Bending, Binding and Placing Steel Bars in RCC Work
- Steel bars are clear, free from loose mil scales, dust, loose rust and any oily materials.
- The bars used at site are manufactured from reputed brand and have a full length.
- Use full length steel bars in beams, slabs etc if not possible,
proper overlap should be given in steel bar and overlap should be
staggered.
- Tor, ribbed and twisted steel bars are used as they have more
tensile stress. Also they are economical and have more strength in
cement concrete.
- The bars must be in full length according to the design.
- Proper sizes/ height of crank bars are given in slab and beams etc.
- Proper support under crank bars of beams and slabs must be given.
- Steel bars are not disturbed while lying cement concrete.
- If steel bars are more in number in beams, the bars are placed in two layers by giving spacer between the layers.
3) Checklist/Points before Laying Cement Concrete
- Form work /shuttering should be checked for line, level and its strength.
- Steel bars and their placing should be checked.
- Proper cover to steel bars and adequate numbers of sports/chairs under crank bars must be checked.
- Proper planks or plates provided for walking over reinforcement are not disturbed during working.
- Raw materials should be proper and sufficient in quantity.
- Electrical pipes, fan box etc. should be laid before lying cement concrete.
- Gap in shuttering plates is sealed properly by jute bags /mortar /rubber etc.
- Shuttering plates are properly oiled.
- Curing arrangement must be checked in advance for smooth curing after laying RCC slab.
- Precautionary arrangements are taken in case of rains etc.
Mass Concrete
Mass
concrete means cement concrete used for constructions of dams, massive
structures, raft slabs and heavy structure beam foundation. There should
be rigid/strict control on concrete work with view to ensure
durability, strength, and uniformity. In big projects detailed
specification is issued separately for individual project according to
site requirement and other situation at site of work. Mass concrete is
used in important project having heavy load and different types of
stresses. Any small deviation in specifications or any irregularity
omitted or committed may cause failure of the structure.
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24 Comment(s) |
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| | By N.S.BISHT - On 6/29/2015 10:34:59 AM | | What is the ratio of Cement, crushed Stone& Sand and size of stone in Concrete. |
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| | By Anonymous - On 1/15/2014 8:15:23 PM | | Now
constructing 2BHK on ground and want to go in for 2 single bedroom
houses on first floor. Should we provide concealing beams. What should
be the thickness of moulding. |
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| | By Anonymous - On 9/19/2013 9:49:36 AM | | This article is very helpful because it is very simple sentence. |
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| | By Anonymous - On 8/23/2013 7:58:08 PM | | extremely infirmative......keep up the good work... |
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| | By Anonymous - On 4/8/2013 11:04:10 AM | | your site teach like a civil engineering professor i respect your people and your company |
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| | By ssrinivasan - On 8/20/2011 7:27:18 PM | | How to maintain the correct length and line of various columns? |
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| | By Anonymous - On 2/14/2011 4:15:23 PM | | It
is very very useful for all type of technicians/ engineers related to
this field and even for a novice. Its a basket of knowledge to share.I
gained lot of knowledge. |
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| | By Manoj Kumar Verma - On 12/29/2010 12:28:33 PM | | this
site is really a lot working in a comman man, i like to suggest all my
friends to have precious knowledge through this site thanks a lot ghar
expert team |
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| | By vijayakumar G - On 12/27/2010 8:13:21 AM | Sir,
I need the proper detail of mixing details(ratios) for each concrete work & brickwork.
Please specify the ratio details of each work |
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| | By Anonymous - On 11/10/2010 12:22:28 PM | | This was a very valuable information..in fact ghar expert is a very good site |
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| | By Anonymous - On 8/21/2010 1:16:33 AM | the given tips are very helpful for technical and even a layman person can takes use of it.
it
will be great if you add pls soje technical terms as crank length,
cantilever precauctions, some useful structure behavior tips,
with regards
Ar.Gurpreet Arora |
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| | By Ahmed Raza - On 7/24/2010 1:49:58 AM | | Herewith
i would like to ask the quantity steel, cement, aggregate, water,
sand, chemical in per cubic meter for columns or beams. thanks |
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| | By shivprasad - On 5/19/2010 7:51:03 PM | | i
am constructed the round wall of diameter 30 feet & 30 feet height
& 4.5 inch width,so please say what quantity of material to be use
for cement concrete (useing steel). |
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| | By shivprasad - On 5/19/2010 7:50:19 PM | | i
am constructed the round wall of diameter 30 feet & 30 feet height
& 4.5 inch width,so please say what quantity of material to be use
for cement concrete (useing steel). |
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| | By shivprasad - On 5/19/2010 7:50:02 PM | | i
am constructed the round wall of diameter 30 feet & 30 feet height
& 4.5 inch width,so please say what quantity of material to be use
for cement concrete (useing steel). |
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| | By tkalaiva - On 3/6/2010 7:06:01 PM | | I WOULD LIKE TO KNOW HOW MUCH RE INFORMCENT STEEL SPACING REQUIRED FOR Residential build (Indipedent house) |
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| | By NAGENDRA SRIVASTAVA - On 1/9/2010 10:38:15 AM | | IF THERE IS ANY PROCEDURE TO PAINT THE STEEL BARS BEFORE USING IT IN COLOMNS AND BEAMS. |
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| | By Anonymous - On 12/24/2009 5:34:28 PM | | its very greatful and helpful for me plese send me extra detail in my mail id |
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| | By Anonymous - On 7/18/2009 12:02:12 PM | | very
helpful for new job seekers.try to give more information like what is
meant be tension , compression and where they will occur in a beam,slab
etc.. |
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| | By sharmishtha - On 6/8/2009 11:09:43 AM | In stair slab use 12 mm MS steel bar .
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| | By Pujesh Mallick - On 6/5/2009 11:31:18 PM |
what should be the size of steel bar in stair slab. |
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| | By Anonymous - On 2/9/2009 1:24:24 AM | We are looking for supply of Y12 steel bars. Please quote us 25, 000 mt. CNF Mombasa.
Regards,
John Mangeli |
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| | By Anonymous - On 2/8/2009 12:49:08 AM | Dear Sir,
I am purchasing house in 13 storey new house which is in foundation
stage.please give me the following details.Steel bars size
required,foundation depth,cement req.for foundation and how much curing
required for foundation pillars if they r using 53 grade cement |
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| | By anilkishor - On 8/17/2008 11:25:34 AM | | it is very helpfull in acquiring knowledge and gain the practical experience |
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we improve it. We welcome both negative and
positive comments. | |
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| | Your name :S L Gupta |
| | Email address :SLGupta@GharExpert.com |
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| | | | | | | Discuss in forums | Do you need more information? Discuss
with other community members in the
Forums area of the site. Enter details below! | |
| | Your name :S L Gupta |
| | Email address :SLGupta@GharExpert.com |
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Guidelines for Laying Cement Concrete Fl... |
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| Tue Sep 01, 2015 | Post #2 | JAI PRAKASH
Join date: May 2014 | 80 cm gap is too high.
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| Wed Sep 02, 2015 | Post #3 | bala
Join date: Jul 2014 | Dear jai sir,
I could not understand the term gap... 80 cm is vertical length of 2 steel bars each which is going to be over lapped | | |
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| Wed Sep 02, 2015 | Post #4 | bala
Join date: Jul 2014 | Dear S L Gupta sir,
Thanks for your response
If the height of the open steel which is to be over lapped is less than 80 cm ( for example we say approx. 50,55,65,60 cm each ( 4 nos ))
How to proceed sir ? How to reinforce this area ?
Thanks
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| Wed Sep 02, 2015 | Post #5 | JAI PRAKASH
Join date: May 2014 | Clear cover to main reinforcement in
Footings : 50 mm
Raft foundation Top : 50 mm
Raft foundation Bottom/ sides : 75 mm
Strap Beam : 50 mm
Grade Slab : 20 mm
Column : 40 mm (d>12mm) 25 mm (d= 12mm)
Shear Wall : 25 mm
Beams : 25 mm
Slabs : 15 mm or not less than diameter of the bar.
Flat Slab : 20 mm
Staircase : 15 mm
Retaining Wall on Earth : 20/ 25 mm
Water retaining structures : 20 / 30 mm
Sunshade (Chajja) : 25 mm Hook for stirrups is 9D for one side No. of stirrups = (clear span/Spanning) + 1 For Cantilever anchorage length for main steel is 69D “L” for column main rod in footing is minimum of 300mm Chairs of minimum 12 mm diameter bars should be used. Minimum diameter of dowel bars should be 12 mm Lap slices should not be used for bar larger than 36 mm. In steel reinforcement binding wire required is 8 kg per MT. Lapping is not allowed for the bars having diameters more than 36 mm. Minimum number of bars for a square column are 4 and for circular column are 6. Longitudinal reinforcement should not be less than 0.8% and more than 6% of gross C/S. Weight of rod per meter length = d2/162 where d is the diameter in mm All reinforcement shall be free from mill scales, loose rust & coats of paints, oil or any other substances. Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness. In case of spacing of bars
Provide the diameter of the bar, if the diameter of the bar are equal.
Provide the diameter of the larger bar, if the diameter are unequal.
5mm more than the nominal maximum size of the coarse aggregate. | | |
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Pillar Work-Construction Questions (38) | |
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