Monitoring of corrosion Potential and Mechanical Resistance of Contaminated Concrete Exposed to a Chlorinated Environment

Abstract

The electrochemical and mechanical behavior were evaluated for specimens of concrete clean and contaminated with 2 and 4% of NaCl (of the weight of cement), elaborated with two types of cements: compound and waterproof. The dosage of the mixture of concrete was done on the basis of weight in two 0.45 and 0.65 water/cement ratios. The specimens under study were exposed in two media: clean water and 3% of NaCl solution. The test to evaluate the presence of corrosion of the reinforced steel consisted in the monitoring of the half cell potentials as the norm ASTM C-876-91 indicates. For the mechanical behavior the compression test was used, according to the ASTM C-39/C 39-M-99 norms. This paper presents the results obtained for the first 4 months of monitoring, identifying the influence of the attack of chlorides in the corrosion of steel and its mechanical properties. There is no a significant influence of the type of cement on the parameters of the study.Keywords: concrete, steel, corrosion, potentials, chlorides. IntroducciónLa corrosión del acero de refuerzo es la causa más importante del deterioro prematuro de las estructuras de hormigón reforzado [1]. Estudios en E.U.A por parte de la NACE muestran que en 1998, en el territorio estadounidense, tan solo en lo que se refiere a puentes, los cálculos de costos directos anuales ascendían a US $3.800 millones [2]. El costo del ciclo de vida se ha convertido en un factor muy importante para los ingenieros constructores y profesionales en reparación, así como para las dependencias responsables de las estructuras, muelles, puentes,

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

“…(1) Half-cell potential (HCP) measurements versus Cu/CuSO 4 electrode (CSE), Model 8-A, Tinker & Rasor®, using a high impedance digital multimeter conforming to ASTM C876-91 R99 [5,13,[27][28]. (2) Electrochemical cell current (ECC) measurements, versus CSE using zero resistance ammeter (ZRA), Model ZM3P (Corrosion Service®) [29][30][31].…”

“…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]. 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]. 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].…”

Cymbopogon citratusand NaNO2Behaviours in 3.5% NaCl-Immersed Steel-Reinforced Concrete: Implications for Eco-Friendly Corrosion Inhibitor Applications for Steel in Concrete

“…This could lead to insidious failure of the steel-reinforced concrete structure culminating in economic losses, especially, in the bid to avert catastrophic injury to life and property via costly repairs, 2 International Journal of Corrosion rehabilitation, and maintenances of the corrosion-damaged structure [15,16]. These engender interests globally from construction stakeholders, researchers, and governments on how corrosion-induced problems could be mitigated, and it is such that costly budgets are allocated in many countries to corrosion related issues alone [15,[17][18][19].…”

“…Techniques proffered for mitigating chloride-induced steel-in-concrete corrosion include use of steel or concrete surface coating, stainless steel, fibre reinforced polymer encasement, cathodic protection, electrochemical chloride extraction, and corrosion inhibitors [3,[19][20][21][22][23][24][25]. Among these techniques, the use of corrosion inhibitors attracts much preference due to its economically lower cost, labour saving, and ease of applications, all combined with its relative effectiveness at mitigating corrosion of steel embedded in concrete [20,[26][27][28][29][30].…”