Premature or untimely weakening or crumbling of cement concrete structures due to corrosion of rebars is indeed a big problem, both financially and technically. According to some recent studies, it shows that many countries worldwide spend a considerable sum of money every year to mend or repair deteriorating concrete structures. The studies even show that some countries have to change the entire structure due to failing rebars. No doubt, that repairs and replacements are too expensive, but aside from such expenses, it is the inconveniences caused to people that make a tremendous impact on the economy of the country.
The primary reason for corrosion or oxidation of rebar is due to the infiltration of chloride from water that contains salt. Since most of the structures and buildings are made of ordinary steel or iron rebar that lacks corrosion resistance properties, they corrode easily with the infiltrated chloride. Concrete structures have a high resistance to compressive stresses and to provide them tensile strength, rebars are cast in them. When corrosion forms on the rebars inside the concrete, this tensile strength weakens. This weakening of tensile strength results in cracking and crumbling of the concrete until it is entirely fallen apart. To overcome this issue, five strategies had been laid down and they are as follows:
1. Apply dense layer of concrete that may eliminate infiltration or ingress of chloride into the structure.
2. Apply cathodic protection or other chemical compounds to restrain corrosion.
3. Use sealants like plastic foams, paint, fabric mats, or clay on the surface of concrete structure.
4. Discover non-metallic and robust reinforcing element.
5. Use corrosion resistance steel as reinforcing bars.
First three strategies were impractical as well as expensive, and the fourth strategy that has been put into use recently, lacked credibility. The only feasible as well as economical solution was to implement the fifth strategy.
The use of corrosion resistance steel as reinforcing bars introduced stainless steel rebars. Stainless steel rebars are easy to produced, robust, and highly corrosion resistive in nature. Compared to concrete structures using ordinary steel or iron rebars, the concrete structures using stainless steel rebars can last up to 125 years.
These days, such stainless steel rebars have become an essential part of all the concrete structures. Whether be it tunnels, highways, retaining walls, skyscrapers, or any other cement concrete structures, the use of stainless steel rebars is imperative. With the introduction of such rebars, now there is no problem of premature or untimely weakening or crumbling of cement concrete structure due to corrosion of rebars.
