08-08-2014, 02:48 PM
NEW GENERATION STAINLESS STEEL REINFORCEMENT BARS FOR CONCRETE STRUCTURES
Introduction
Construction builds the basic framework and infrastructure of a country . One of the products traditionally used to reinforce concrete is plain carbon steel. Large number of reinforced structures are starting to show serious signs of deterioration, particularly those over 30 years of age due to corrosion of reinforcement. This necessitates costly and time-consuming repairs and maintenance of the structure.
What Causes Corrosion?
Chloride ion is the main culprit
Chlorides may be incorporated into the original mix due to their presence in the sand, aggregate or water. Chlorides penetrate through the "cover" when the external surfaces of the concrete are exposed to seawater, marine atmospheres.
When steel corrodes, it forms an oxide layer. These corrosion products-oxides-have a larger volume than the original steel.
What Is Stainless Steel?
Stainless steel is low carbon steel. It is an alloy of iron with chromium content over 10.5%.Also nickel,molybdenum and certain other alloying elements are added
Chromium is the alloying element that imparts to stainless steel their corrosion resistance qualities
Ferritic
Ferritic stainless steel has properties similar to mild steel but with the better corrosion resistance. These are plain chromium stainless steels with varying chromium content between 12 and 18%, but with low carbon content
Austenitic-ferritic (Duplex):
Austenitic-ferritic (duplex) duplex stainless steels have a metallurgical structure that is a combination of both ferritic and austenitic. They have a high chromium content (from 18 to 26 percent) and a low nickel content (from 4 to 7 percent). Most grades also contain some molybdenum (from 2 to 3 percent)
Conclusions
Despite the initial cost, there is considerable potential in savings of life cycle cost, especially infrastructures, which are exposed to corrosive environment
Best suited material at all temperatures. Also stainless steel are suited for cryogenic applications
Available in different grades and hence significant savings can be done
Also the material is available in different forms, which is more advantageous
Material is new generation and environmental friendly hence can be very rightly utilized as a new generation material for all applications