MYTHS & REALITIES

REALITY :
  • Galvanizing is done at a temperature of 450-460 degree centigrade, whereas the properties of steel change only at a temperature above 700 degree centigrade. Thus there is no possibility of any changes in steel properties.
  • Extensive tests carried out at TATA Steel prove that there is no variation in the steel characteristics before and after galvanizing.
  • Tests conducted in Torsteel Research Foundation, Sardar Patel College of Engineering, Bangalore, TCR Engineering and various international studies have conclusively proven the same.
REALITY :

Studies done across the world and in India have proven that bond strength remains the same after galvanizing, and in same cases even increases as compared to black steel. This is due to the formation of calcium hydroxyzincate when the Eta layer of zinc combines with the surrounding concrete.

REALITY :

The first project using galvanized rebars in India was the Lotus Temple in Delhi in early 1980’s. Since then numerous projects have used it across the country, in marine applications, in jetties, buildings, water retaining structures, sewerage treatment plants, temples, strategic projects etc. There is an exclusive Indian Standard IS 12594: 1988 for galvanization of rebars.

REALITY :

Galvanized rebars have excellent chloride resistance and with stands chloride ingress several times the threshold chloride leaves for black steel. It has very good passivity and withstands both high and low PH leaves. Bridges constructed in regions using heavy de icing salts and passing over the sea using Rebarz have performed excellently even after 30-40 years.

REALITY :

Galvanized coatings provide cathodic protection to steel. This means that zinc being higher in the electro chemical series of metals, is more electro positive to steel, and hence tends to donate electrons to steel. Hence even when there is a cut or damage on surface of steel, zinc sacrifices itself and covers up the crack, by natural process. This totally removes the possibility of holiday and crepe corrosion as observed in other coatings.

REALITY :

Most of the coatings are fragile in nature and tends to peal off during handling and transportation. This than requires wide spread touch ups and even then tends to corrode from exposed areas. However galvanizing produces four zinc iron alloys, which have hardness, values much higher than steel. These alloy layers makes the coating abrasion resistant and with stands rough handling, dragging and pouring of concrete. Also it can be stored on site for long period in the open with no affect on its properties. This makes galvanizing the most user friendly technology.