Cq bar by meaning comersial quality bar and BS are British Standard by meaning.Cq bar are cheaper than BS bar but the not enough size or diameter and let say 12 mm diameter,one side 8mm but at one side 12mm and looklike oblong shape.The BS bar come with the certificate from supplier or the hardware shop.The link bar also have a CQ and BS edition.The 6mm link size are looklike 3 mm by diameter.The new requirement by JKR only R10 are allowed for link.
BRC are mill by varies of size from type A,B,C and D.The size of bar are from 10mm to 6mm.The A type are square 200 mm x 200 mm,for B type are rectangular in shape 200mm x 100mm,C type are 100mm x 100mm and D type are 100mm x 50 mm.The BRC also have a CQ and BS quality.For determine at site to know the quality is the BS delivery are by sheeting and the CQ quality can fold.The usually lapping length is 600 mm.The BRC at the edge of slab must insert in the beam and at the drop area like toilet and wc are,the BRC must be continously connection between drop.
- Rusty bar and tensile test
Because of PKP,many of construction site would have to stopped activity at least 3 or 4 month.To continue all the rusty bar weather fixed already or not must be clean from rust by brushing or by sending to lab for tensile test only for uncover re bar.That why the lapping bar have to cover with plastic to protect re bar from moist if the activity want to stop for a long time.
Test bar for tensile,the sampel of 1 m long for each size of re bar is sending to test and the result must be more than 460 N/mm2 for high tensile bar and 250 N/mm2 for mild tensile bar.If failed all the buddle of bar must reject.If the lapping bar also failed,must be replaced with new lapping re bar.
Sometimes a size of re bar not enough or short a little of quantity and the new delivery may be take a long time ,so at the size only have a big size only.Let say in the drawing the bottom bar need 3T12 but shortage and want to replace with T16 and the calculation of re bar area for each size must do for equivalent.Let say 1T12 the area is 112.4 m2 and for 1 T16 the area is 201.60 m2.For 3T12,the total area is 337.2 m2 must be replace with 2 T16,area 403,20 m2 that ok but dont follow the numbers only without calculate the area.
Origionally the re bar shedule is purposely use by QS to calculate the quantity of rebar in metre run and lasty convert to kg to put a price in the BQ.There are a rules and regulation and formula to calculate the 90 and 45 degree bend and lapping to get a total length.For at site purpose,the bar shedule is very important to know the shape,length and total length of each beam or each element to calculate the re bar for ordering purpose and workers supply and calculate time for complete the job according the meet the shedule.
Dowel bar is bar inserting to casted concrete to joint to the new structure.Dowel bar size must at least 16 mm and 60 D projecting out to new structure element.Re bar in the casted structure must drilled and use a special cement at the base of dowel bar.Lapping length is always occured in the re bar work.Lapping length is 40D for tension and 60D for compression area.D is the biggest size of the 2 lapping bar.Let say one 12 mm in size and one 16 mm in size,so the D is taken 16 mm of 40D.
Welding works for connection re bar in special condition are allowed and MOS of the process is to be submitted.Coupler are used only for big size of re bar at the congested area.Coupler are costly are only used at big project only.
2.TIE OF RE BAR
https://youtube.com/shorts/PybuAXvwKDw?feature=share
The function of re bar in the concrete are to carry a tension force from the load and tansfer to the column and then transfer to the footing and then transfer to the soil.
There are 3 step to make the fixing of rebar completed process in the element of concrete structure.
First are to cut the bar to follow in the drawing length with the cutter or bender machine and secondly to bend the bar follow the bendinh shedule and bending regulation.
Thirdly are to tie between bar with a gi wire.There are many style of tying and can learn or view from the bar bending website and the important of the tie is to make sure the position of the re bar are maintain follow the design and drawing along the concreting process.
Now days there are a new techology using a high resistance plastic to replace these old material and easy to knot it to the position.
From these short video these are the final process of re bar fixing before final inspection before concreting.
Hope can learn something from the video.Thank you
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