Manufactured by Steel Brands, Zimbabwe

What are TMT Bars ? TMT – Thermo Mechanically Treated Bars High strength reinforcement bars in different strength grades BS – 4449 (1997), Gr. 460 and ASTM A615, A706, Gr. 460 which achieve their properties by on-line thermo processing www.steelbrands.co.zw

TMT Bar Usage Areas where TMT Bars are being suitably used because of High strength & Corrosion resistance properties Bridges Fly-overs Multi – Storied Buildings Concrete Roads Underground Construction Dams Industrial structures Marine structures And of course your SWEET HOME www.steelbrands.co.zw

Product Characteristics of TMT BARS Chemistry As per IS: 1786/’85 In Production of TMT bars, Carbon content is restricted to below 0.25% for better Ductility, Bend- ability and Weld-ability. Carbon % Max. Sulphur % Max. Phos. % Max. S+P % Max. Fe-460 0.25 0.060 0.11 Fe-500 0.055 0.105 Fe-550 0.050 0.10 www.steelbrands.co.zw

Properties Mechanical Properties of TMT Bars as per IS: 1786-85 Grade BS 4449-1997 Yield Stress (N/sq.mm) 469 Tensile Strength (N/sq.mm) 506 Elongation minimum 14% (Av. 18%) Required Steel Composition Grade BS 4449-1997 Max. Carbon 0.14 – 0.25 % (for 10mm to 25 mm bars) Max. Sulphur 0.06 % Max. Ph. 0,06 % Manganese ----------- 0.5% to 0.8 % ---------- www.steelbrands.co.zw

Micro – Macro Structure Microstructure of TMT bar Tempered Martensite Rim Ferrite Pearlite Core www.steelbrands.co.zw

Comparison of Mechanical properties of TMT BARS with Conventional Bars Re-bar Quality IS:1786 conventional re-bars TMT BARS Grade Fe-415 Fe-500 Fe-550 Fe-460 Yield Strength, Mpa Min. 415 500 550 460 UTS, Mpa Min. 485 545 585 580 630 Elongation, Min. 14.5 12 8 22 20 18 Bend up to, Min. 3d 4d 5d 2d www.steelbrands.co.zw

Special Features of TMT BARS Higher Strength combined with higher elasticity (elongation) as compared to other re-bars Excellent weld-ability Resistant to fire hazards Excellent Ductility Higher Fatigue strength Easy work-ability at site Fulfills bonding requirement with Concrete Fulfills all requirements of BS-4449-1997 www.steelbrands.co.zw

Advantages of Producing TMT BARS Reduction in secondary scale losses Lower cost of production Less manpower requirement No off-line processing, hence, bars are ready for dispatch Lower inventory Product value addition www.steelbrands.co.zw

Customer Requirements Lower construction Costs due to Higher Strength combined with better elongation Reduction in total weight of reinforcement bars requirement Earthquake Resistance Better corrosion resistance Heat Resistance Better weld-ability Easy availability of better material www.steelbrands.co.zw

Advantages of Using TMT BARS Savings in steel consumption Reduction in civil construction cost Better Safety of Civil Structures Resistant to earthquakes Resistant to fire hazards Better Corrosion Resistance properties Easy working at site owing to better Ductility & Bend-ability Good Weld-ability www.steelbrands.co.zw

Comparison of TMT Bars with CTD Bars Properties CTD Bars TMT Bars Strength Maximum up to Grade Fe-415 Grades of Fe-460, Fe-500 & 550 are easily available. Elongation (Elasticity) As per IS: 1786/’85 Elongation achievable more than 50% in comparison to CTD Bars. Weld-ability Preferably avoided as welded joints are weak. Better and no loss of strength. Formability Bend 3D – 5D, Re-bend 5D – 8D. Excellent due to uniform elongation. Bend 1D, Re-bend 4d Ductility & Fatigue Strength High Higher than CTD bars hence most suited for earthquake resistant structures. Fire Hazards Loss of Strength on temperature rise. Negligible loss in strength up to 500 deg. C. Corrosion Resistance Scales fall down during cold twisting. Better Corrosion resistance. Overall Economy Lower Costs & Faster working.

Weight & Cost Savings of TMT BARS CHARACTERISTICS CTD 415 TMT 460 TMT 50 DESIGN STRENGTH 415 N/sq. mm. 460 N/sq. mm. 500 N/sq. mm. QTY. REQUIRED 1.000 MT 0.854 MT 0.809 MT % of SAVING IN WT. OVER CTD 415 14.6 % 19.15 % SAVING w.r.t. CTD 415 / MT US$ 15 US$ 25 % of SAVING w.r.t. CTD 415 6.8 % 12.0 % www.steelbrands.co.zw

Additional cost saving by using TMT BARS with welded joints Type of Lap Lap Length required Material Requirement % Cost saving per joint/bar Conventional based on concrete steel bonding. Avg. 50 dia.= 1000 mm lw = 50 D 2.47 kg. Of Bar For Welded lap joints 6.3 dia. = 126 mm lw = 6.3 D 0.31 kg of Bar 65% www.steelbrands.co.zw

Savings by using TMT BARS Section Grade of Concrete Grade of Steel Qty. in Kg. % of Saving in Cost over fy-250 CTD-415 AXIALLY LOADED COLUMNS 20 302 - 189 32% TMT-460 169 39% 10.4% UNIAXIAL BENDING WITH COMPRESSION 115 76 28% 70 34% 8% www.steelbrands.co.zw

Some typical Examples of Savings depending on structural design Office Building: Total Saving 12.8% Hotel: Total Saving 14.1% House: Total Saving 11.9% Industrial hall: Total Saving 13.6% www.steelbrands.co.zw

Thermo mechanical treatment process After Finishing stand, bar passes through Quenching system and receives a short /intensive cooling of the surface. Surface of bar is converted to hard martensite structure while core remains austenitic. The core re-heats the quenched surface and tempers the external martensite. The surface and core temperatures become equal. This is called the Equalizing temperature. On further cooling on the cooling beds, the remaining austenite transforms into a fine grained pearlite structure. www.steelbrands.co.zw

Schematic layout of quenching plant From Cold Water Sump Gate Valve Cold Water H.P. Pump House High Pressure Header Ball Valves Finishing Stand Pinch-Roll Quenching Box Flying Shear Compressed Air Line Cooling Bed www.steelbrands.co.zw

Special Safety Features of TMT Bars Earthquake Resistance Heat Resistance Corrosion Resistance www.steelbrands.co.zw

Earthquake Resistance properties of TMT bars TMT bars have high fatigue resistance due to their high ductility. This feature makes them most suited for Earthquake resistant structures and equipment foundations.

Requirements for earthquake resistance Stiffness Strength Ductility www.steelbrands.co.zw

Concrete Homes Reinforced Concrete Homes Stand Up to Earthquakes Built according to good practices, concrete homes can be among the safest and most durable types of structures during an earthquake. Homes built with reinforced concrete walls have a record of surviving earthquakes intact, structurally sound and largely unblemished. In reinforced concrete construction, the combination of concrete and steel provides the three most important properties for earthquake resistance: stiffness, strength, and ductility. Why reinforced concrete is safe? Reinforced concrete walls are a composite system: Concrete resists compression forces, and reinforcing steel resists tensile forces produced by an earthquake. The concrete is cast around the bars, locking them into place. The exceptional ductility of the steel to resist tensile forces, coupled with the rock-like ability of concrete to resist compression, results in an excellent combination of the three most important earthquake resistance properties: stiffness, strength, and ductility. Studies have shown that properly designed reinforced concrete walls offer greater earthquake resistance than other types of construction. www.steelbrands.co.zw

TMT Bars for Earthquake Resistance For Earthquake Resistance structures need to be provided with balanced Stiffness, Strength& Ductility between its members, connections & supports. TMT Bars provide very high strengths with comparatively higher Elongation Values along with better Ductility as compared to other Rebars. Better Weld-ability of TMT Bars helps in making high strength connections with other sections with little overlap. “A Chain Breaks at its Weakest Link” www.steelbrands.co.zw

Stress-Strain Curves www.steelbrands.co.zw

Comparison of % Strain for TMT bars & CTD bars www.steelbrands.co.zw

Need for Earthquake-Resistant Buildings Stable Ground Good foundation High Grade Cement Reinforcing Material Reinforcing Steel CTD bars/ TOR Steel TMT Bars Inherent Qualities of TMT Bars: High Ductility & High Elongation High Fatigue Resistance to Dynamic / Seismic Loading High UTS / Proof Stress Ratio www.steelbrands.co.zw

Heat Resistance Properties of TMT BARS In TMT bars, test results have shown no loss of strength up to 500 deg. C. In the temperature range 550 to 600 deg. C, the Yield strength decreases by 20 N/ sq. mm. Only. Hence TMT bars can be used in places prone to fire hazards. In CTD bars there is a large loss of strength at elevated temperatures.

Effect of Temperature increase on Yield Point www.steelbrands.co.zw

Corrosion Resistance Properties of TMT BARS Corrosion Tests indicate that TMT Bars are comparatively less prone to corrosion than cold twisted deformed bars. In TMT Bars the protective layer of scale, which normally falls down during cold twisting, protects against corrosion. Moreover, stress corrosion is also avoided in TMT bars as internal stresses are absent as compared to CTD bars.

Various Corrosion Tests www.steelbrands.co.zw

Conclusion: Suitability of TMT Bars in Hill Architecture Higher Yield Stress to UTS Ratios Higher Elongation Earthquake Resistance Heat Resistance Weld-ability www.steelbrands.co.zw

I used Conventional Bars I used NEXUS TMT