Rebar Corrosion In Concrete Research Articles

Design of a long-period fiber grating sensor for reinforcing bar corrosion in concrete

In this article, a fiber monitoring technique for detecting the state of rebar corrosion in concrete is proposed, which uses the sensitivity of the long-period fiber grating (LPFG). In this technique, the configuration of a LPFG rebar corrosion sensor is carefully designed to detect the changes of refractive index around rebar in concrete caused by chloride and liquid rust. In the experiment, the sensor using the corresponding package was embedded in concrete structures. The LPFG spectrum curves corresponding to different refractive indexes of the environment under test were captured by the monitoring technique of LPFG transmission spectra, and the relationship between the resonance peak wavelength and the state of rebar corrosion in concrete was obtained. The experimental results numerically showed that the sensor response has good regularity for a wide range of travel.

Improvement of Resistance of Concrete Against Chloride Ingression Using a New Admixture

This paper studies a new admixture used to improve the resistance of concrete against the chloride penetration. The minerals blends, e.g., fly ash and GGBFS, can significantly improve the resistance of concrete against chloride penetration, which is one of the main reasons causing the corrosion of rebar in concrete. Another measure used to recover the resistance of rebar against corrosion is corrosion inhibitor. The new admixture investigated herein is fabricated by combination of corrosion inhibitor and mineral additive to form a new admixture. One of the typical composition of the new admixture is (in mass percentages) with calcium nitrite 20%~30%, calcined gypsum 15%~20%, instant layered sodium metasilicate 5%~10%, hexamethylene tetramine 3%~5%, sodium tripolyphosphate 1%~3%, water reducer 0% ~20%, AEA 0% ~ 0.4% (optional) and fly ash. Series of tests have been carried out to verify the performance of the new admixture. The results showed that by adding the new admixture with mass dosage of 3~5% of the cementitious materials into concrete, the penetration of chloride of chloride into concrete is significantly slowed down. Also, the new admixture is compared with conventional products experimentally and it is proved that the new admixture does have advantage in the resistance against corrosion of steel bars in concrete.

Real-Time Monitoring of Rebar Corrosion in Concrete

Real-time monitoring of concrete of rebar in concrete is studied in this paper, electrochemical method is the simplest method, monitoring of corrosion of rebar in concrete. This method is simple in an ever-changing environment, can reflect the corrosion of rebar in a long time.It not only can detect the rebar corrosion rate, also can test the long-term corrosion quantity. With the help of the polarization resistance measured regularly, the quantity of rebar corrosion can be estimated in a certain time.

Electromagnetic Metrology on Concrete and Corrosion.

To augment current methods for the evaluation of reinforcing bar (rebar) corrosion within concrete, we are exploring unique features in the dielectric and magnetic spectra of pure iron oxides and corrosion samples. Any signature needs to be both prominent and consistent in order to identify corrosion within concrete bridge deck or other structures. In order to measure the permittivity and propagation loss through concrete as a function of temperature and humidity, we cut and carefully fitted samples from residential concrete into three different waveguides. We also poured and cured a mortar sample within a waveguide that was later measured after curing 30 days. These measurements were performed from 45 MHz to 12 GHz. Our concrete measurements showed that the coarse granite aggregate that occupied about half the sample volume reduced the electromagnetic propagation loss in comparison to mortar. We also packed ground corrosion samples and commercially available iron-oxide powders into a transmission-line waveguide and found that magnetite and corrosion sample spectra are similar, with a feature between 0.5 GHz and 2 GHz that may prove useful for quantifying corrosion. We also performed reflection (S11) measurements at various corrosion surfaces and in loose powders from 45 MHz to 50 GHz. These results are a first step towards quantifying rebar corrosion in concrete.

Effectiveness of pretreatment method to hinder rebar corrosion in concrete

This paper aims to evaluate the ability of phosphate pretreatments applied on steel rebars to hinder the corrosion reinforcements using synthetic pore electrolyte and mortar contaminated by chloride ions. The electrochemical behaviour of the pretreated substrate was assessed by corrosion potential, polarisation resistance and electrochemical impedance spectroscopy measurements. The results have demonstrated that the treatment of the rebar by immersion in the Na3PO4 (0·5M) solution favours the formation of a passive layer on the steel rebar surface, which increases the resistance to corrosion initiation up to 0·3M Cl– instead of 0·1M Cl– without treatment. The pretreatment also provides enhancement of corrosion protection of the steel rebar in mortar. The evolution of the impedance spectra in function of chloride concentration is in a fairly good agreement with the results obtained from RP measurements.

Monitoring corrosion of reinforcement in concrete structures via fiber Bragg grating sensors

Corrosion of steel and rebar in concrete structures is one of the most frequent reasons for civil infrastructure failures. Thus, improving the effective corrosion sensor technology can greatly reduce cost and provide safe structures with long service lives. However, assessing the corrosion condition of rebars is not simple because they are buried in concrete. In this paper, using fiber Bragg grating (FBG), a corrosion sensor for monitoring steel rebars embedded in a concrete structure is developed and validated by experiments. Based on the fact that the volume and diameter of a rebar embedded in concrete will enlarge due to corrosion, an FBG packaged with fiber-reinforced plastics (FRP) is wrapped on the steel bar. During corrosion, the increase in the bar diameter leads to the increase in fiber strain, which can be measured by the shift of the wavelength of FBG. Performances of the corrosion sensor are validated by accelerating corrosion in lab experiments. The corrosion sensor is embedded in a concrete specimen put in a 5% sodium chloride solution with a constant current. Experimental results show that the corrosion sensor can monitor the concurrence of corrosion of rebars in concrete. The corrosion extent can be quantitatively evaluated through the change in the wavelength of FBG. Therefore, the corrosion sensor developed in this paper is feasible for monitoring the early corrosion of rebars in concrete.

Utilization of ultrasonic wave reflection technique to detect corrosion of rebar in concrete

Utilization of ultrasonic wave reflection technique to detect corrosion of rebar in concrete

Effect of Cracks on Corrosion of Rebar in Concrete Studied by Wire Beam Electrode

Effect of Cracks on Corrosion of Rebar in Concrete Studied by Wire Beam Electrode

An evaluation of the stability of concrete by Nyquist criterion

Impedance function is the characteristic function of concrete. Apart from Kramers-Kronig transform, another criterion named after Nyquist can also be applied to evaluate system stability. Nyquist criterion is derived from Cauchy's theory of conformal mapping. A so-called Nyquist contour is defined on the right-half complex plane and mapped onto the complex plane of impedance function. From the number of zeros, poles, and encirclements of image function origin, the stability of the system could be evaluated. An example of corrosion of rebar in concrete is given to show the applicability of the criterion.

Application of Acoustic Emission Technique to Detection of Rebar Corrosion in Concrete

Application of Acoustic Emission Technique to Detection of Rebar Corrosion in Concrete

The electrochemical behaviour of steel under polarization in porous media simulating concrete

For simulating the corrosion of rebars in concrete, steel wire specimens were wrapped in porous polyvinyldiene fluoride sheets and placed in solutions corresponding to cement pore waters of various ages and possibly polluted with chlorides. The corrosion behaviour of steel was determined with potentiodynamic curves. For a given solution, peaks appear on these curves, at potentials which depend on the solution pH. The plots giving the peak potentials versus the solution pH include four straight parallel lines. The sizes of the pores influence these critical potentials because in small pores, the products formed at the metal-solution interface are not able to move freely.

Rebar Corrosion under Simulated Concrete Conditions Using Galvanic Current Measurements

Abstract A galvanic current measurement method was developed as a rapid and simple technique to study the effect of chloride concentration, welding, and bending on the rebar corrosion in concrete. ...

The Use of Harmonic Analysis to Monitor Steel Rebar Corrosion in Concrete

The Use of Harmonic Analysis to Monitor Steel Rebar Corrosion in Concrete

Approach to the effect of concrete resistivity in the corrosion of rebars in concrete

The concrete resistivity has been considered as a factor which affects the corrosion rate of the rebars. Untill now the only relation found has been stablished between potentials and resistivity for steel embedded in Chloride contaminated concrete. In this paper a comparison between corrosion rate of rebars, determined from Polarization Resistance method, and Electrical Resistance data measured through the electronic compensation of the ohmic drop are given. The results of i corr and R ohm has been measured for rebars embedded in mortar made with three different types of cement. The specimens were submited to an accelerated carbonation. The relation between i corr and R ohm is quite similar in all the cases and suggests that the concrete electrical resistivity may be a controling factor of the corrosion rate of the rebars.