Corrosion Inhibitors for Reinforced Concrete

Abstract

Reinforced concrete has been widely used in the last century, however, due to aggressive agents such as carbonic gas and chloride ions, it suffers premature deterioration. The concrete is a physical barrier that protects steel from corrosion, and the alkalinity of concrete leads to the formation of a passive layer around the reinforcement, which increases protection against corrosive processes. However, concrete is a porous material and has cracks that allow the entrance of aggressive agents, destabilizing the passive layer and corroding steel. The corrosion is the major cause of deterioration of concrete structures and several methods of protection and repair have been developed to increase the durability of such structures. Corrosion inhibitors, chemical substances that reduce the corrosion rate, have been widely used, both for prevention and correction. Inhibitors are classified according to their method of application, their mechanism of protection and chemical composition. In this chapter, through a literature review the main inhibitors used in reinforced concrete structures and their acting mechanisms are presented, as well as their efficiency and some side effects on concrete. It is very important to know the different types of inhibitors for correct use, thus increasing the life span of reinforced concrete structures.

Ammonium Phosphate as Inhibitor to Mitigate the Corrosion of Steel Rebar in Chloride Contaminated Concrete Pore Solution

“…Initially, once steel (Fe) is exposed in the solution simultaneously it forms Fe(OH) 2 as a corrosion product (Equation (6)). Generally, this corrosion product (Equation (6)) is very unstable and soluble [ 59 ]. Therefore, there is a possibility that Fe(OH) 2 transforms into another oxide by reacting with the inhibitor rather than adsorption onto the steel rebar surface.…”

Sustainable Corrosion Inhibitors for Concrete

“…Amines and alkanolamines have been extensively employed as an organic inhibitors due to their good solubility in water as well as they do not affect the behaviour of concrete [12]. Alkanol amine derived inhibitors might be used to reduce chloride as well as carbonation induced corrosion.…”

Quantificação De Manifestações Patológicas Em Concreto Armado, Metodologia Gde/Unb Estudo De Caso

“…A presença de cloretos no concreto, advindos da água do mar, da atmosfera marinha, de aditivos aceleradores de pega que contenham CaCl2, de água ou agregados contaminados ou de poluentes industriais, é uma das principais causas de corrosão das armaduras de concreto armado (ALMEIDA, SALES, 2014). Na presença de cloretos, o filme passivador pode ser destruído mesmo em valores de pH superiores a 11,5 e pequenas quantidades são necessárias para despassivar a armadura, relacionada com a quantidade de hidróxidos disponíveis nas soluções presentes nos poros do concreto (RIVETTI, et al, 2018). A presença dos cloretos traz à estrutura agentes ácidos que acabam por tornar um ambiente alcalino para a armadura em um ambiente ácido, estando condicionada a espessura do cobrimento nominal à concentração do dióxido de carbono no meio ambiente da edificação.…”