Anti – corrosive coatings

anti-corrosive-coatings
Generally, we conclude ourselves with the presence of water as a reason for corrosion taking place in steel. But technically that is not the actual reason and the chemical reaction happening during the process of corrosion has something to do with water(H2O). To understand corrosion to the next state, First, we need to know what is corrosion and the properties of steel. Corrosion is generally known as or identified as “Rusting of Rod”, but technically Corrosion is the chemical reaction between the steel and its surrounded materials which cause deterioration to the metal and its properties. First of all, Why steel corrodes? Steel is not a naturally occurring material, Iron ore is smelted into steel and in this process, a lot of energy is added to the steel. But steel is thermodynamically unstable and starts to revert to its original state which is iron ore or Rust. Corrosion does not happen all at once. For corrosion to happen there must either two metals or the same metal in two positions, an Electrolyte, a metallic connection. Comparing the requirement for corrosion with a Reinforced concrete Structure, we could easily relate the rebars, concrete, and ties respectively. Once all the three conditions are positive, the electrochemical process which involves the flow of charges begin, which results in, the iron atom loses its electron and move into the concrete as ferrous ions. This process is called a Half Cell Oxidation reaction.  2Fe → 2Fe2+ + 4e-  So the ions in the concrete flow towards the cathode where they react with water and oxygen in the concrete and this is where the water plays its role in corrosion of steel and as said earlier that is not the only reason for corrosion. A reduction reaction takes place at the cathode and then the ferrous ions migrate through the concrete pores and form iron oxides or rust. Though it is not an immediate process, concern for corrosion is mandatory because once the reaction is started and corrosion begins, the bond between the compression member and tension member is affected and it may also lead to spalling of concrete surfaces. Corrosion can be prevented in various ways with modern construction techniques and construction material which are as follows, 1. Quality concrete is the first step towards the prevention of corrosion, the concrete with a water-cement ratio not more than 0.5 to prevent carbonation and 0.4 to prevent Chloride penetration. 2. The usage of superplasticizers like Tec Mix 550 and water reducers will provide highly effective concrete. 3. Reduction of usage of ingredients that has chlorides in them will prevent the chances of corrosion. 4. Air entrainment is one effective way to provide good quality concrete. Air entrainment can be easily achieved by using relevant air-entraining admixtures. This not only prevents corrosion but also reduces bleeding and excessive cracking. 5. The provision of Sufficient cover is a vital method to delay the corrosion. The chloride penetration and carbonation occur from the outer surface of the concrete. Increasing the cover will increase the time for chloride ions to reach the concrete and thus increases the onset of corrosion. The above methods will prevent corrosion to an extent by providing quality concrete. Now, there is a very effective modern method that could assure one hundred per cent corrosion prevention. Providing a Zinc Rich Anti-corrosive coating will provide one hundred per cent corrosion resistance to the steel rod. The Proper Application of Anti-corrosive coating like TEC BEAT ZR would provide a better result in corrosion prevention. Tec Beat ZR or any other anti-corrosive coating material is mostly an Epoxy-based material, so it will be either two or more component mix. The first important part of concentration is surface preparation, The steel must be dust, rust or other contaminants. Once the surface is ready. The second step is Mixing. Mixing of anticorrosive coating has to carried with caution and it should not be diluted or allowed to thin. The two-component Tec Beat ZR is mixed using a steel paddle with no formation of air bubbles. Then the application of Tec Beat ZR is done with the brush ensuring the coat is not broken. Once the coat is dried, it will act as a barrier layer between the metal, electrolyte, and the Metallic Connection and due to this, the reaction between the 3 components is prevented and so the corrosion of the steel rod.