Corrosion Rate Evaluation on Steel in Concrete Exposed to Sulfate Solutions

Electrochemical Performance of Phyllanthus Muellerianus on the Corrosion of Concrete Steel-reinforcement in Industrial/Microbial Simulating-environment

“…This remaining protrusion of steel-rebar was painted with glossy paint after casting of each steel-reinforced concrete slabs. Slabs of steel-reinforced concretes, having 0.5 water cement ratio [3], were cast in duplicates, according to the replication design suggested by Haynie [24], and for this, six concrete block duplicates were cast, with each duplicate admixed with similar P. muellerianus concentrations. These totalled twelve concrete block specimens.…”

“…Corrosion of steel-reinforcement in concrete is a major problem affecting the structural integrity of building structures and infrastructures, for which steel-reinforced concrete, due to its versatility, low cost and ease of manufacture, remained the material of choice globally [1][2][3]. Normally, steel reinforcement (steel-rebar) embedment in concrete is protected by a layer of thin oxide film in the highly alkaline concrete pore at pH > 12 [1,[4][5][6].…”

“…Acidifying agents of the environment include sulphuric acid from acid rain and wastewater in industrial environments [3,[7][8][9] and from sulphur reducing microbial activities in sewage environments [10][11][12]. Acidic sulphate from these sources attacks concrete, forms volume expansive products and an electrochemical cell of corroding steel-reinforcement that could eventually culminate, if unchecked, in the collapse of the steel-reinforced concrete structure [3,5,11]. In many studies, the use of corrosion inhibitors as admixtures in concrete has been identified as an easy and effective technique for mitigating corrosion degradation of steel reinforced concrete in acidic sulphate environment [4,[8][9]13].…”

“…However, aggressive acidifying agents of the environment lower pH in concrete, thereby breaking the passive oxide layer, and render concrete steel-rebar susceptible to corrosion degradation. Acidifying agents of the environment include sulphuric acid from acid rain and wastewater in industrial environments [3,[7][8][9] and from sulphur reducing microbial activities in sewage environments [10][11][12]. Acidic sulphate from these sources attacks concrete, forms volume expansive products and an electrochemical cell of corroding steel-reinforcement that could eventually culminate, if unchecked, in the collapse of the steel-reinforced concrete structure [3,5,11].…”