www.sefindia.org

[mssteel15 at yahoo.co.in]

Dear Sir,

I would like to know more about mechanical Rebar coupler for Splicing of Rebars for reducing congestion of rebars.

Which one is better :-

1) Taper threading (Ishita)  or cold forged parallel threading (Dextra).?

a) I want to know particularly in case of  Taper threading Splicing  ,  when you cut the thread  in rebar in cone shape you are actually removing outer martensite crust which is mainly responsible for TMT strength . In the Test report provided by manufacturer the fracture always occured in thread slipped?  What is performace of rebar undersuch condition?

b) One the other hand in parallel threading  since the thread is cut straight  the martensite remains  but  the manufacturer  say that he is  doing additionally doing cold forging  which add strength due to cold  working ?  In the Test report provided by mnaufacturer the fracture is always outside the coupler area in rebar.?  What is the effect of cold forging on TMT bars? What metallurgy test can be done to verify the microstructure ?

c) What should be the criteria to accept  Mechanical Rebar coupler ?

Thanking You

Sincerly Yours

M.GUPTA


          
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