Role of Carbon Dioxide on the Corrosion of Carbon Steel Reinforcing Bar in Simulating Concrete Electrolyte

العوامل الرئيسية التي تجعل حدوث تآكل حديد التسليح في الخرسانة ممكنا هي أيونات الكلوريد وامتصاص ثاني أوكسيد الكاربون من المحيط . ويعمل كل منهما حسب آلية معينه تؤدي الى تدميرالطبقة الواقية الموجوده على سطح حديد التسليح في الخرسانة .في هذا العمل، تمت دراسة تأثير ثاني أوكسيد الكاربون في محلول الخرسانة الاصطناعي على سلوك التآكل لقضبان حديد التسليح المصنوعة من الصلب الكربوني (CSRB) بطريقة فعالة باستخدام تيارمن غاز ثاني أوكسيد الكاربون في تراكيز مختلفه تتراوح بين 0.03 – 2.0% ، وتم تتبع تأثير ارتفاع درجة حرارة المحلول الالكتروليتي في المدى بين 20 إلى 50 درجة مئوية. استخدمت منحنيات تافل, منحني الاستقطاب الرجوعي لاستخراج عوامل التآكل وسرعه التأكل وقابلية  حصول تاكل نقري على التوالي. تمت دراسة التغير في التركيب المجهري و تضاريس السطح  في CSRB بعد الاستقطاب في محلول الخرسانة المحاكاة باستخدام المجاهر الضوئية والقوة الذرية.بينت النتائج ان سرع التاكل ازدادت بوجود غاز ثاني اوكسيد الكربون و هذه الزيادة اعتمدت طرديا مع زيادة تركيز الغاز.لم يسجل وجود تاكل تنقري لحديد التسليح في محلول الخرسانه الاصطناعي في جميع تراكيز غاز ثاني اوكسيد الكربون وان التاكل العام هو السائد  في جميع الظروف تحت الدراسة.The main factors that make it possible to get the corrosion of reinforcing steel in concrete are chloride ions and the absorption of carbon dioxide from the environment, and each of them works with a mechanism which destroys the stable immunity of rebar in the concrete. In this work the effect of carbon dioxide content in the artificial concrete solution on the corrosion behavior of carbon steel reinforcing bar (CSRB) was studied, potentiostatically using CO2 stream gas at 6 level of concentrations;  0.03 to 2.0  weight percent, and the effect of rising electrolyte temperature was also followed  in the range 20 to 50ᴼ C. Tafel plots and cyclic polarization procedures were obeyed to investigate the corrosion parameters and pitting susceptibility respectively. The change in the microstructure and morphology of the CSRB after polarization in the simulate concrete solution was studied using optical and atomic force microscopes. The results show that the corrosion rate of the CSRB in artificial concrete greatly increases with the existence of CO2 gas and highly depends on its concentration in the range 0.03 to 2.0% .No sign for pitting corrosion is recorded at all CO2 concentrations and the general corrosion is the main problem in the conditions under consideration. &nbsp

Review on Strain Monitoring of Aircraft Using Optical Fibre Sensor

Structural health monitoring of aircraft assures safety, integrity and reduces cost-related concerns by reducing the number of times maintenance is required. Under aerodynamic loading, aircraft is subjected to strain, in turn causing damage and breakdown. This paper presents a review of experimental works, which focuses on monitoring strain of various parts of aircraft using optical fibre sensors. In addition, this paper presents a discussion and review on different types of optical fibre sensors used for structural health monitoring (SHM) of aircraft. However, the focus of this paper is on fibre bragg gratings (FBGs) for strain monitoring.  Here, FBGs are discussed in detail because they have proved to be most viable and assuring technology in this field. In most cases of strain monitoring, load conditioning and management employs finite element method (FEM). However, more effort is still required in finding the accurate positions in real time where the sensors can be placed in the structure and responds under complex deformation

Review on Strain Monitoring of Aircraft Using Optical Fibre Sensor

Structural health monitoring of aircraft assures safety, integrity and reduces cost-related concerns by reducing the number of times maintenance is required. Under aerodynamic loading, aircraft is subjected to strain, in turn causing damage and breakdown. This paper presents a review of experimental works, which focuses on monitoring strain of various parts of aircraft using optical fibre sensors. In addition, this paper presents a discussion and review on different types of optical fibre sensors used for structural health monitoring (SHM) of aircraft. However, the focus of this paper is on fibre bragg gratings (FBGs) for strain monitoring.  Here, FBGs are discussed in detail because they have proved to be most viable and assuring technology in this field. In most cases of strain monitoring, load conditioning and management employs finite element method (FEM). However, more effort is still required in finding the accurate positions in real time where the sensors can be placed in the structure and responds under complex deformation

An Optical Interferometric Triaxial Displacement Sensor for Structural Health Monitoring: Characterization of Sliding and Debonding for a Delamination Process

This paper presents an extrinsic Fabry-Perot interferometer-based optical fiber sensor (EFPI) for measuring three-dimensional (3D) displacements, including interfacial sliding and debonding during delamination. The idea employs three spatially arranged EFPIs as the sensing elements. In our sensor, the three EFPIs are formed by three endfaces of three optical fibers and their corresponding inclined mirrors. Two coincident roof-like metallic structures are used to support the three fibers and the three mirrors, respectively. Our sensor was calibrated and then used to monitor interfacial sliding and debonding between a long square brick of mortar and its support structure (i.e., a steel base plate) during the drying/curing process. This robust and easy-to-manufacture triaxial EFPI-based 3D displacement sensor has great potential in structural health monitoring, the construction industry, oil well monitoring, and geotechnology

Monitoreo estructural basado en sistemas de sensores de fibra óptica

Este artículo presenta un compendio de métodos para realizar monitoreo en diferentes tipos de estructuras mediante sensores de fibra óptica. Para el análisis de los diferentes métodos se analizaron panoramas de todas partes del mundo,teniendo como principal exponente a China por el desarrollo de un mayor número de sistemas y porque sus modelos están a la vanguardia del monitoreo estructural, incluso con gran aplicación en otros países. Se tuvieron en cuenta sistemasdesarrollados en los últimos cinco años y se presenta una síntesis de los resultados de dichos sistemas en torno a sus ventajas, beneficios y principales características. Se encontró con este artículo que, ya que el monitoreo estructural atañe a distintas disciplinas, para la investigación de los sistemas de fibra óptica en monitoreo, se tuvieron muy en cuenta igualmente sistemas de otras áreas distintas a la electrónica, como lo son la ingeniería civil, la ingeniería de minas, la ingeniería estructural e incluso la medicina

Feasibility of Distributed Fiber Optic Sensor for Corrosion Monitoring of Steel Bars in Reinforced Concrete

This study investigates the feasibility of distributed fiber optic sensor for corrosion monitoring of steel bars embedded in concrete. Two sensor installation methods are compared: (1) attaching the sensor along the bar and (2) winding the sensor on the bar. For the second method, optical fibers were winded spirally on steel bars with different spacings: 0 mm, 2 mm, 5 mm, and 10 mm. Steel bar pull-out testing was conducted to evaluate the effect of presence of distributed sensor on the bond strength of steel—concrete interface. Electrochemical testing was carried out to assess the influence of the installation methods on the corrosion resistance of the reinforced concrete. Winding the optical fiber on steel bars with a 10-mm spacing does not affect the bond strength and corrosion resistance and allows real-time corrosion monitoring. The distributed sensor data can be used to estimate the corrosion induced steel loss and predict concrete cracking

Nondestructive monitoring techniques for crack detection and localization in RC elements

This paper presents the structural and damage assessment of a reinforced concrete (RC) beam subjected to a four-point bending test until yielding of reinforcing steel. The deterioration progress was monitored using different nondestructive testing (NDT) techniques. The strain was measured by distributed fiber optic sensors (FOSs), embedded prior to concrete pouring. The initiation and propagation of cracks were monitored by acoustic emission (AE) sensors attached to the surface of the material. The recorded AE activity results in good agreement with FOS strain measurements. The results of the integrated monitoring system are confirmed by visual observation of the actual crack pattern. At different loading steps, digital image correlation (DIC) analysis was also conducted

Monitoring Concrete Deterioration Due to Reinforcement Corrosion by Integrating Acoustic Emission and FBG Strain Measurements

Corrosion of concrete reinforcement members has been recognized as a predominant structural deterioration mechanism for steel reinforced concrete structures. Many corrosion detection techniques have been developed for reinforced concrete structures, but a dependable one is more than desired. Acoustic emission technique and fiber optic sensing have emerged as new tools in the field of structural health monitoring. In this paper, we present the results of an experimental investigation on corrosion monitoring of a steel reinforced mortar block through combined acoustic emission and fiber Bragg grating strain measurement. Constant current was applied to the mortar block in order to induce accelerated corrosion. The monitoring process has two aspects: corrosion initiation and crack propagation. Propagation of cracks can be captured through corresponding acoustic emission whereas the mortar expansion due to the generation of corrosion products will be monitored by fiber Bragg grating strain sensors. The results demonstrate that the acoustic emission sources comes from three different types, namely, evolution of hydrogen bubbles, generation of corrosion products and crack propagation. Their corresponding properties are also discussed. The results also show a good correlation between acoustic emission activity and expansive strain measured on the specimen surface

Four-point Bending Based Low-Carbon Steel Plate Corrosion Monitoring by Optical Fiber Bragg Grating Strain Sensor

Fiber Bragg Grating (FBG) Sensor is very sensible to strain change, with 1.2 pm shift in Bragg wavelength when suffering 1 μm strain change [1]. Metal corrosion is big problem in our world. In order to monitor this process, many methods are proposed, but seldom focus on the strain change of metal plate during corrosion. One reason for this is that the strain change during corrosion is much smaller than the sensitivities of most sensors. Another problem is the residual strain left in metal products, which will also be released during corrosion without an obvious regularity. Our solution is applying a bending to the metal plate, keeping curvature radius at the medium of the metal plate unchanged during corrosion. As to the residual strain, which has a non-negligible influence in order of magnitudes, we set another metal plate made in same process without bending. By comparing the results of the bent and unbent plates, the strain changes only contributed by the bending during corrosion can be achieved. We calculate a model to analyze the strain changes contributed by bending during corrosion. The expected result is that the rate of strain change during corrosion is always in positive correlation with the corrosion speed. After 500 hours corrosion experiment, the low-carbon steel (0.13-0.20% Carbon) plate with 1.59 mm in thickness at the beginning corroded 0.1202 ±0.0088mm, the total strain change contributed by bending is 91.213 ±3.158με. The rate of strain change during corrosion for the results is positive during corrosion, fitting the expectation very well