Efficiency of 2 Aminopyrimidine as Corrosion Inhibitor under Chloride and Carbonated Environment

Abstract

The durability problems encountered in reinforced concrete structures are of serious concern to the concrete infrastructure across the world. The durability of reinforced concrete structures is dependent on the surrounding environmental and exposure conditions. One of the major factors responsible for the deterioration of reinforced concrete structures is the corrosion of reinforcement inside the concrete. The corrosion of concrete takes place majorly due to CO2 and chloride present in the environment. Reinforcement corrosion is generally accompanied by the loss of reinforcement cross-section and a build-up of corrosion products. The corrosion products occupy a larger volume than the original steel, this in turn generates tensile stresses causing cracking and spalling of the concrete cover. Thus, decreasing the service life of the Reinforced Concrete structure.

The purpose of this thesis is to study the effectiveness of 2-Aminopyridine as a corrosion inhibitor against the Carbonation as well as Chloride induced corrosion. Firstly, the experiment was conducted on the pore solution simulating concrete and the effectiveness of inhibitor was checked. Then, concrete specimens using OPC and PPC were cast using the inhibitor and checked under carbonation and chloride induced corrosion. Three types of tests, i.e., Linear polarization Method, Half cell potential and Galvanic potential are performed to find out the values of Icorr and HCP. Cubes were also cast using OPC and PPC to check the carbonation depth in the concrete.

From the results, it was observed that corrosion current i.e. Icorr values were reduced both in pore solution as well as concrete. The inhibitor takes time in forming the layer around the rebar and reducing the corrosion rate in concrete as well as pore solution. The amine group in the 2-Aminopyridine forms a chelate ring around the steel bar. This makes a passive layer around the steel bar, hence providing resistance to corrosion. The carbonation depth was also controlled by the inhibitor admixed specimens as compared to the non-inhibitor admixed specimen.