Best-in-class lifecycle costs in corrosive concrete environments

Top12 is an innovative reinforcing steel with significantly improved corrosion resistance and best-in-class lifecycle costs, developed by Steeltec in Switzerland. Top12:

  • is a high-alloy class 1.4003 material and much more resistant to corrosion than conventional reinforcing steels because it contains at least 12 mass percent chromium.
  • requires no special handling and can be conventionally processed.
  • is approx. four times more resistant to chlorides than conventional reinforcing steel. This reliable protection from corrosion can extend the lifetime of structures many times over.
  • requires only a very low concrete cover due to its higher corrosion resistance in case of chloride or CO2 attacks.
  • In its geotechnical version with higher yield strength, it renders the usual sheathing tube of the anchor system redundant, as it provides the necessary protection for temporary and permanent anchors of protection level 2 in any ground - even in aggressive groundwater.

Contact and expert advice

Dr. Marc Zintel
+49 151 5748 5059
Send e-mail
Advantages at a glance

  • High-alloy 1.4003 material
  • Best-in-class life-cycle cost
  • Ideal solution for many engineering and geotechnical applications
  • Approvals in Germany and Switzerland 
  • > 1500 applications and successfully in use for > 20 years
Available forms

  • Steel bar 
  • Wire rod
  • Geotechnical anchor

Durability tailored to operating needs

Corrosion caused by chlorides is the most common form of reinforcement corrosion. Chlorides penetrate the concrete and, above a certain chloride concentration on the reinforcement level, initiate corrosion. Depending on the corrosion resistance of the reinforcement, damage occurs faster or slower. This in turn is related to the alloy content and surface properties of the stainless steel. This means that the corrosion resistance of the steel can be influenced proactively. To improve the reliability and durability of structures and taking the overall costs into account, an optimized material selection is crucial. As the alloy content increases, not only the resistance of stainless steel increases, but also the material costs. The aim is to select the reinforcement according to the corrosion stress and the intended service life in a balanced cost-benefit ratio.

Best in class life-cycle costs for different structural applications

Cost reduction while ensuring high durability and robustness - a challenge to be solved more and more frequently while planning and repairing infrastructure buildings. With our stainless reinforcing steel Top12, we provide the answer. Top12 increases durability, offers practical construction advantages and keeps life cycle costs at the minimum.

Comparison of different service life calculations (w/z=0,45; β=0,5)
  Component Steel grade Chloride contamination
Concrete layer
Binder Calculated lifetime [a] Target lifetime [a]
  Bridge caps non-alloy steel 3,5 50 / 6 CEM II/B-S 14 50
  Top12 >100
  Bridge center columns non-alloy steel 3,0 55 / 8 CEM II/B-S 73 100
  Top12  +30kg/m2 FA >>100
  Tunnel emergency  walkways non-alloy steel 5,0 50 / 6 CEM II/B-S 10 50
  Top12 55
  Tunnel interior walls non-alloy steel 4,0 60 / 6 CEM II/B-S 68 100
  Top12  +30kg/m2 FA >>100
Comparison of life cycle costs

Comparison of the different variants (standardized to Top12) with regard to life cycle costs - vertical axis cut off at 5.0


Top12: Technical data

Mechanical properties

Min. yield strengths (Rp0.2) expressed in N/mm²

Product Yield strength Rp0,2 Yield to tensile strength ratio Rm/Rp0,2 Elongation at max. load Agt
[Mpa] [ - ] [ % ]
Top 12-500 500 1,08 5,0
Top12-670 670 1,08 5,0
Physical properties
Density in kg/dm2 Electrical resistance at 20°C in (Ω mm2)/m Magnetisa-bility Thermal conductivity at 20°C in W/(m K) Specific heat capacitiy at 20°C
in J/(kg K)
Young's modules in GPa at »20°C Mean thermal expansion coefficient in 10-6K-1 »20°C
 - 100°C
7.7 0.60 yes 25 430 210 10.40
Chemical composition (in % by weight)
Si Mn P S Cr Ni N
0.015 0.70 0.50 max. 0.025 max. 0.005 min. 12.00 0.50 0.02
Delivery options
Type Top12-500 Top12-670
Wire rod (pickled, coiled) Ø 8 / 10 / 12 / 14 mm  -
Steel bar (pickled)  - Ø 16 / 20 / 28 / 36 / 43 mm

Approvals and related applications for Top12


  • DIN 488 (German standard): Top12 has two general building approvals from the German Institute for Building Technology (DIBt); approval number: Z-1.4-266; Z-1.4-272
  • SIA 262 (Swiss standard): Top12-500 and Top12-670 are listed in the “Register normkonformer nichtrostender Betonstähle”.

Civil engineering and underground projects

  • Caps and guide walls
  • Retaining walls
  • Bridge central pier
  • Tunnel walls and portals
  • Tunnel emergency walkway
  • Pile caps and pile head beams
  • Bored piles

Building construction projects

  • Columns, walls, foundations of park buildings
  • Precast concrete elements
  • Sandwich elements
  • Architectural concrete

Geotechnical applications

As nails for:

  • Excavation
  • Slope stabilization
  • Rock nails
  • Tunnel construction
  • Falling object protective structures

As piles for:

  • Foundation plates
  • Bridge foundations
  • Foundation refurbishment
  • Underpinning
  • Buoyancy prevention
  • Absorption of horizontal forces

Take a look at a field study how Top12 compares to other rebar steels

Corrosion results after 12 years under real conditions in an Alps road tunnel (concrete cover 10mm)

Field tests in the Naxberg tunnel in Switzerland have shown impressively how different steels behave under high but common chloride loads from road traffic. Both the unalloyed reinforcing steel and the galvanized reinforcing steel exhibited considerable pitting corrosion and each had a corroded steel surface of over 70%. Top12 showed small rust spots, but no measurable material erosion could be determined for these spots. The duplex steel showed no signs of corrosion and was still passive after 12 years.

with rolling skin 
Duplex steel

Background knowledge: about the production of Top12

Top12 is five times more corrosion resistant

The secret of the excellent mechanical-technological material properties and high corrosion resistance lies in the production of steel: a decisive factor is the selective addition of alloys in the steel melt, including more than 12 % chromium. The ribbed reinforcing steel is manufactured using a patented rolling process. After rolling, the steel is controlled and specifically cooled down to obtain its very good mechanical properties. In order to increase corrosion resistance in line with requirements, Steeltec pickles the Top12 after hot rolling - a further step to increase corrosion resistance by a factor of five. Pickling removes the so-called rolling skin. As a result, the bar surface is smoother and more homogeneous and the ribbed steel is protected against surface corrosion and pitting. Whereas the conventional, unalloyed reinforcing steel B500B withstands a chloride content of approx. 0.5% wt.%/z, this value is up to five times higher in the Top12.


The result: Calculated no repairs over 100 years service life

Therefore, the formula for achieving the calculated service life in civil engineering is made up of the following components: Concrete + adequate reinforcement cover + Top12. Calculations on the prime example of motorway bridge central piers show that building owners or operators can safely achieve the target service life of 100 years without any maintenance measures with Top12. Without Top12, i.e. with a conventional B500B, the pier has to be extensively repaired at least once.




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