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As mechanical splicing replaces lap joints on Indian sites, the coupler becomes the load path. Testing runs to IS 16172, and more than fifty manufacturers have been taken through the ISI mark route on this bench.
TCR is the first BIS-accredited commercial laboratory in India for IS 16172 rebar coupler testing across all diameters, from 8 mm to 40 mm. Over fifty manufacturers have been guided through the ISI mark certification process. The capability covers tension test, uniform elongation, fatigue cycling at 100,000+ cycles at specified stress ranges, slip measurement, and cyclic tension-compression reversal.
TCR Engineering Services, based in Navi Mumbai, specialises in the testing and evaluation of TMT (Thermo-Mechanically Treated) rebars and reinforcement couplers. As the construction industry shifts towards modern methodologies, mechanical splicing of reinforcement bars using couplers has emerged as a reliable technique.
Importance of Mechanical Splicing
Mechanical splicing involves the end-to-end joining of two reinforcement bars using couplers. This technique is particularly advantageous in structures subjected to cyclic loading and where inelastic yielding may occur, such as multi-story buildings and bridges. The use of couplers reduces congestion during concreting, accelerates construction timelines, and ensures a more efficient load transfer between bars. To ensure safety and reliability, the quality of both the couplers and the TMT rebars must be rigorously assessed, considering factors such as material compatibility and construction standards.
TCR Engineering conducts testing in accordance with several established standards, including:
IS 16172: 2023: This standard outlines the requirements for mechanical splices of reinforcement bars.
IS 1786: This specifies the requirements for TMT rebars, including their mechanical properties.
IS 16651:2017: Standards for TMT made of SS material.
ASTM A1034: This standard specifies the requirements for mechanical splicing of bars.
ISO 15835-2: This standard covers the testing procedures for mechanical couplers.
TCR Engineering utilizes a variety of testing methods to ensure the integrity and performance of TMT rebars and their couplers:
TMT Testing - IS 1786:2008
Static Tensile Test: Determine the tensile strength and elongation of TMT rebars (Grades Fe 500 D, Fe 415 D/S, up to 45 mm diameter) per IS 1786.
Bend and Re-Bend Tests: Evaluates ductility and flexibility by bending specimens to specified angles and then straightening to inspect for cracks or failure.
Spectro/Wet Chemical Analysis: Confirms chemical composition of TMT rebars as per IS 1786 and IS 16651 (for SS materials).
Rebar Coupler Testing - IS 16172:2023
Static Tensile Test: Evaluates tensile strength on static machines.
Slip Test: Measures permanent extension post-loading (performed before cyclic testing).
Cyclic Tensile Test: Evaluates splice behaviour under cyclic loads, typically 100 cycles at stress levels from 5% to 90% of yield stress, according to relevant standards, without loss of static tensile strength.
Low Cycle Fatigue (LCF) Test (10,000 Cycles): Tests endurance under alternating loads of the splice in such a way that they should withstand 10,000 cycles of alternating tension and compression without failure.
High Cycle Fatigue (HCF) Test (2 million Cycles): Measures durability under extensive cyclic loads with parameters including:
Minimum Stress: 30 MPa
Maximum Stress: 130-350 MPa
Frequency: 3-10 Hz
Reporting: S-N curve documentation.
Common Material Grades: EN8D and 45C8 for rebar couplers.
Equipment: Tests are conducted on advanced machines, static tensile and slip test performed on a static machine and fatigue tests (cyclic, LCF, HCF) on a dynamic machine. Closed-loop servo-hydraulic dynamic UTM machines enable testing frequencies from 0.035 to 30 Hz, ensuring precision and reliability.
Coupler Sizes and Standards
TCR conducts rebar coupler testing across diameters from 8 mm to 40 mm, ensuring compatibility with rebar grades like Fe415, Fe500, and Fe550, in compliance with standards such as IS 16172. All tests align with TCR’s NABL accreditation (ISO/IEC 17025:2017), emphasising the company’s dedication to quality and accuracy.
Clients in this segment include Dextra, Afcons, Mumbai Coastal Road Project, and Larsen and Toubro Mumbai Metro.
Coupler manufacturers tested include Dextra, Leviat, Kridhan, Vrudhhi Steel, Sanfield, Kamar Infra, Rajasthan Alloys, Beacon Infra, Steel Era, Kuber Infra Solution, Splicetek India, and Shrinidhi Innotech. End-project clients running TCR-tested couplers include NHSRCL, NHAI, Larsen and Toubro, Afcons Infrastructure, NCC, Tata Projects, K. Raheja Corp, Megha Engineering and Infrastructures, Oberoi Realty, KEC International, Shapoorji Pallonji, Ahluwalia Contracts, Dilip Buildcon, Ashoka Buildcon, and Lodha.
TMT rebar testing per IS 1786: tensile, yield, elongation, re-bend, weldability, chemical composition. Couplers tested per IS 16172 (parallel threaded, tapered threaded, compression, and grouted types). Pull-out test on TMT Bars per IS 2770. HT strand testing for High Speed Rail (HSR) and bridges. Aluminium formwork qualification.
Standards: Coupler evaluation is run to IS 16172:2023 (mechanical splices of reinforcement bars), ASTM A1034 (mechanical splices of bars), ISO 15835-2 (test methods for couplers), with rebar to IS 1786 and stainless reinforcement to IS 16651:2017.
Test programme: Static tensile and slip on a static machine; cyclic tensile at 100 cycles across 5 to 90 percent of yield without loss of static strength; low-cycle fatigue at 10,000 cycles of alternating tension and compression; and high-cycle fatigue to 2 million cycles at 30 MPa minimum and 130 to 350 MPa maximum stress, 3 to 10 Hz, reported with the full S-N curve. Common coupler grades are EN8D and 45C8, across rebar grades Fe 415, Fe 500, and Fe 550.
Equipment: Closed-loop servo-hydraulic dynamic universal testing machines run from 0.035 to 30 Hz, separating static, slip, and fatigue work onto dedicated frames.
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TCR is the first BIS-accredited commercial laboratory in India for IS 16172 rebar coupler testing across all diameters from 8 mm to 40 mm. Manufacturers seeking the ISI mark can run the complete IS 16172:2023 test programme, static, slip, cyclic, and fatigue, at one NABL ISO/IEC 17025:2017 accredited laboratory.
Couplers are evaluated to IS 16172:2023, ASTM A1034, and ISO 15835-2. TMT rebars are tested to IS 1786 for tensile, bend, re-bend, and chemical requirements, with stainless reinforcement to IS 16651:2017. Parallel threaded, tapered threaded, compression, and grouted coupler types are all covered, with pull-out testing per IS 2770.
Static tensile and slip tests run on a static machine. Cyclic tensile testing applies 100 cycles between 5 and 90 percent of yield stress without loss of static strength. Low-cycle fatigue runs 10,000 cycles of alternating tension and compression; high-cycle fatigue runs to 2 million cycles with full S-N curve reporting.
Testing covers rebar grades Fe 415, Fe 500, Fe 550, and stainless grades under IS 16651, with common coupler material grades EN8D and 45C8. Beyond couplers, the laboratory also runs HT strand testing for high-speed rail and bridges, and aluminium formwork qualification for modern construction methods.
