Corrosion is not something to be taken lightly. It poses a dangerous threat to the overall strength of the building structure. Corrosion starts out pretty much simple and advances through several stages that result in the eventual collapsing of the structure. Even though corrosion is threatening for RCC, there are preventive measures that can be taken to considerably delay the corrosion effects.
The preventive measures
Mainly corrosion prevention in reinforced concrete is done by the following ways which are:
- Anti-corrosion treatment
- Fusion-Based Epoxy coating
In Anti-corrosion treatment, it mainly deals with the prevention of corrosion using alkaline solutions. This process consists of a certain number of steps. The first step begins with the dipping of the reinforced bars in a pickling tank containing a de-rusting solution. The reinforcements are then left in the solution for about 15-30 minutes until all the rust is removed and a bright surface is obtained. In order to prepare about 100 litres of Derusting Solution, 5 litres of derusting solution, 50 litres of Hydrochloric acid and 50 litres of water are mixed together in the pickling tank.
The reinforced steel rods are then cleaned with a wet waste cloth after removing from the pickling tank and immersed in an Alkaline cleaning tank. This tank contains Alkaline solution which is made in the ratio of 1.5 kg. of powder to 400 litres of water. The rods are left for about 5 minutes, cleaned and removed. By the means of a fibre brush, phosphating jelly is then immediately applied on the surface of the rod. The jelly shall be allowed to react with the rod surface for 45-60 minutes and the jelly removed by rinsing in water or wet cloth.
Corrosion inhibitor and sealing
After the removal of jelly, a corrosion inhibitor solution is mixed with ordinary Portland cement to form a semi-liquid mixture, called slurry. It is prepared in the ratio of 500 CC of inhibitor to 1 kg of OPC. This is applied on the surface of the steel rod by brushing. All these steps should be done on the same day and the steel rod must be let to dry for about 12 to 24 hours.
After the inhibitor process, a corrosion sealing solution must be applied by brushing.
reinforcement surface. The coating is then allowed to dry for 12 – 24 hours. After applying the inhibitor solution, a corrosion sealing solution is applied on the reinforcement surface. This coating is again repeated after 4 hours of air drying. After the anti-corrosion treatment, the steel rods are stored above ground in a covered area on wooden or masonry support.
The preventive measures against corrosion don’t end here. They will be explored in Part-II. Stay tuned.