Nonthreaded Rebar Couplers
Rebar couplers are used in the RCC structures to replace the system of lapping and welding in reinforcement. When there is need of long length bars or when joining the additional bars to the end of existing bars, the lapping system is applied that is the bars are tied by wire next to each over. In the same way like lapping, welding is also processed where unlike tied by wire, the bars are attached by welding.
Since, there is a wastage of bar in lapping system and welding system, an alternative system is used known as rebar coupler or the coupler in reinforcement that provides an end to end connection for the continuous reinforcement of a structure. The coupler in reinforcement is used since it is economical and cost efficient unlike the lapping system, where some part of the bar is wasted due to lapping.
The rebar coupler is particularly cost efficient for large diameter bars in the big projects of construction and construction of skyscrapers. The rebar couplers are also commonly known as mechanical splices. The rebar coupler is used in all the construction fields, such as, constructions of buildings, bridges, dams, towers, etc.
Crimping Rebar Coupler
Crimping rebar coupler is known as the first coupler in reinforcement in the construction and after that threaded rebar coupler was introduced. In crimping rebar coupler there is no thread. The rebar coupler without thread is fitted in the two ends of the TMT bar and then the coupler is crimped by a crimping machine.
The crimping coupler is not economical and more material is used and also the labor cost is high. A crimping coupler in reinforcement cannot be uncrimped after installation. Because of this reasons, the crimping rebar coupler system has failed in the market.
MBT Rebar Coupler
The MBT Rebar Coupler is basically designed for the critical conditions of continuous reinforcement. This MBT coupler in reinforcement is used when there is less lap length and not much of a bar is left for the continuous reinforcement. The MBT couplers are also used in the retrofitting constructions. There are 6-8 bolts in the top one MBT coupler.
The length of MBT couplers is more than a threaded coupler. The strength of MBT couplers depends on the number of bolts present on it and with the help of this bolts the coupler in reinforcement is installed.
Rebar Coupler Size Chart
Like the size of the TMT bar, the TMT rebar coupler sizes comes in same, such as, 16, 18, 20, 22, 25, 28, 32, 36, 40 and so on.
Rebar Coupler Testing Procedure
A coupler in reinforcement is processed by many rebar coupler testing. Some of the test of rebar coupler are as follows:
- Cyclic Tensile Test
- Low Cycle Fatigue Test
- High Cycle Fatigue Test
- Static Tensile Test
- Yield Strength of Steel
- Slip Test
- Chemical Test
Advantages of Rebar Couplers
- The rebar coupler improves the structural integrity.
- It reduces the lapping length calculation.
- Rebar coupler increases the bar uses by not wasting bars like the lapping.
- The connection inspection is simple and easy.
- It increases work speed by quick installment.
- It is very economical amongst all the systems of joint in reinforcement.
- The load path continuity is accurate.
- The transferring of the load is proper.
- It doesn’t create congestion.
- The rebar coupler has a great quality control and easy to supervise.