Reval - stainless steel reinforcement bars for construction and concrete structures

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For more information about Reval reinforcement bars visit www.reval-stainless-steel.com

Reval® - What is stainless steel?

Stainless steel is not a single specific grade of steel but a family of steels with a wide variety of characteristics with respect to physical and mechanical properties and resistance to corrosive environments.
There are four ranges of stainless steel that are distinguished by their microstructure and possess different characteristics:

· Austenitic
· Ferritic
· Martensitic
· Duplex stainless steel which have a microstructure with similar proportions of austenite and ferrite.

Corrosion resistance, and other useful properties of stainless steel, are enhanced by decreasing carbon content, and increasing nitrogen, chromium, nickel and molybdenum contents.
Only austenitic and duplex stainless steels are recommended for use as reinforcement to concrete because of their high corrosion resistance.

Why use stainless steel reinforcement bar?

Reval® is the trade Mark for stainless steel reinforcement bar manufactured by Acciaierie Valbruna S.p.A Vicenza (Italy).
Concrete structures produced with Reval® meet all requirements demanded by those projects, in concrete, which need protection from corrosion.
Reval® is therefore the solution to problems of degradation, safety and free Maintenance.

Applications

• National infrastructures: roads, bridges, tunnels,
• Marine infrastructures: harbours, piers, jetties, and dams.
• Long endurance buildings
• Renovation of monuments and buildings
• Construction with anti-fire properties
• Construction with anti-earthquake properties
• Refineries
• Military constructions ( submarine docks)
• Building and laboratories requiring non magnetic structure

Stainless steel advantages

• Superior corrosion resistance to chlorides
• Shock and seismic loading resistant.
• Diverse material selection for specialized military and scientific and research applications
• Fire and heat resistant compared to black bar.
• Low magnetic permeability
• Superior strenght levels
• Durable and self-healing to abrasion and handling damage
• Alloys resistant to localized corrosion mechanisms
• Outstanding ductility, even at high strenght levels
• Expected service life in concrete of 100 years
• Cost competitive over Full life Cycle Cost Analysis
• Long shelf, storage and service life

Resistance to corrosion in concrete

The behaviour of Reval® in very aggressive environments, such as in concrete contaminated by chloride and carbonate, has been compared with different types of steel used in concrete structures.
It has emerged that the exposure to high temperature, 40 degrees C in tropical climates, triggers a general diminution, to the limits, of chlorides stability.
That is more evident in galvanized and in mild steels for which corrosion starts, with an increase of temperature, even with a chloride content between 0.4 and 1%.
Reval® 1.4301, 1.4436 and especially 1.4462, show instead a considerable higher resistance to different levels of ph in concrete and at high temperatures.
That peculiar stability makes those steel, at different levels, suitable in the most aggressive environments where concrete is in direct contact with aggressive elements such as chloride from the sea and de-icing salt.


Le considerazioni che emergono sono le seguenti:
- l'esposizione alle elevate temperature tr (40° C, condizioni climatiche tropicali) provoca una diminuzione generalizzata della soglia di stabilità nei confronti dei cloruri (l'abbassamento più evidente si osserva nell'acciaio al carbonio e in quello rivestito di zinco per i quali, a temperatura ambiente, la soglia critica è rispettivamente 0.4 - 1%).
Reval® 1.4301, 1.4436 e specialmente 1.4462 presenta una considerevolmente alta resistenza ai differenti livelli di ph in calcestruzzo e alle alte temperature.
Questa particolare stabilità rende questi acciai, a differenti livelli, adattabile ai più aggressivi ambienti, in cui il calcestruzzo è in diretto contatto con gli elementi aggressivi come ad esempio il cloro del mare e i sali anti-gelo.

Reval® and mild steel

Il Reval® can be used in structures, joint or welded together with mild steel reinforcing bar.
The success of the joints depend upon proper passivation and absence of chlorides of the mild steel.
Cutting, bending, welding and bonding values are according to the standard in force in Europe.

Anti-earthquake properties

The high ductility of Reval® makes it suitable for areas where earthquake are frequent.
Mechanical properties comply with Eurocode 8 clas DC"M" (ductility class "M").
The high ductility and tenacity of Reval® has been compared at the University of Padua, Venice and Rome to that one of mild steel.
Data related to elongation and toughness, which are basically stable at any temperature, and load, confirm the excellent properties of Reval® in an earthquake environment.

Magnetic Properties

Austenitic stainless steel are also called "paramagnetic" steel due ti their low magnetic permeability.
The use of austenitic Reval® is suggested in projects which could be affected by disturbances in electromagnetic fields created by sources other than those directly required by the project itself such as; hospitals radio and TV stations, banks, submarine docks, meteo stations etc…)

Stability at low temperatures

Reval®, being an austenitic steel, can be used successfully in frost and cold environments which cause cracking in concrete and spalling from the steel beneath.
It has to be noted that Reval® maintains the stability of its austenitic structure down to minus 196°Cand therefore displays suitability in very cold climates.

Behaviour in presence of fire

At the Centre Studi and Anti Fire Experience Laboratory in Rome, Reval® behaviour in fire has been tested by relating the mechanical resistance to the variation of the temperature.
The results reported into the two graphics shown demonstrate that the mechanical values remain within the safety limits at critical temperatures, well above those of mild steel (averaging 500°C at 55% proof stress).
The relevant conclusions are reported in the integral text of the experimental programme.

* For more information about Reval reinforcement bars visit www.reval-stainless-steel.com

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