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TMT bars are thermo-mechanically treated reinforcement steel rods with a tough outer layer and ductile core, widely used in RCC buildings.
Materials · Also: Thermo-Mechanically Treated bar, TMT rebar
TMT bars are thermo-mechanically treated reinforcement steel rods with a tough outer layer and ductile core, widely used in RCC buildings.
Plain-language explanations for planning and learning. Local codes, consultant advice and contract documents take precedence over glossary summaries.
TMT manufacturing quenches the bar surface after rolling, then allows self-tempering so the core remains ductile. Grades (e.g. Fe 500, Fe 550) indicate yield strength. Diameters (8–32 mm common in houses) are chosen by the structural engineer. Market prices are usually quoted ₹/kg and vary by brand, diameter and delivery. Never substitute diameters or lap lengths without engineer approval.
Example: A column schedule might call for 16 mm Fe 500 TMT main bars with 8 mm stirrups — weight is calculated from total length × unit weight for each diameter.
| Unit | Notes |
|---|---|
| mm | Nominal diameter |
| kg / tonne | Purchase and stock unit |
| ₹/kg | Common market quote unit |
Reinforcement
Reinforcement is the steel (usually TMT bars) embedded in concrete to carry tensile and shear forces that plain concrete cannot resist alone.
RCC
RCC (Reinforced Cement Concrete) is concrete strengthened with steel bars so it can resist both compression and tension in beams, slabs, columns and footings.
BBS
A BBS (Bar Bending Schedule) is a table that lists each reinforcement bar’s mark, diameter, shape, cut length and quantity so steel can be cut and bent accurately.
Each Varnarc glossary term includes a simple definition, a technical explanation, a worked example, units where relevant, and links to calculators or materials so you can take the next action. Thin one-line dictionary stubs are not published.
Glossary 2026.08.1
TOR (twisted) bars are an older product. Modern RCC practice in India predominantly uses TMT. Follow the grade specified on drawings.