Cid Andrade

Cid Andrade
Universidade Estadual de Maringá | UEM · Department of Chemical Engineering

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337
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Introduction
Skills and Expertise

Publications

Publications (337)
Preprint
Full-text available
The present project consists of developing a printed circuit in which it is possible to perform cyclic voltammetry in order to be applicable in amperometric biosensors. The circuit contains a programmable potentiostat (LMP91000, Texas Instruments ™) being controlled by a microcontroller (ATmega168PA-MU, Atmel®). The transducer has electrochemical c...
Article
Full-text available
In the present work, the composition of a corroded reinforcing steel surface is studied at different pH values (related to different degrees of development in the corroding zones of the corrosion process) in solutions simulating chloride-contaminated environments. The media considered consist of saturated calcium hydroxide solutions, progressively...
Chapter
Reinforced concrete may suffer rebar corrosion but also other types of attack to the material integrity. When these processes develop actively at significant rate, they usually manifest through cracking of concrete cover, expansions and efflorescences and they are named, for the sake of the service life calculation, as “propagation” periods. The mo...
Article
Stainless steel is a corrosion resistant metal that has now wide record of good performance in several aggressive media, in spite of which is not fully immune to different types of attack. In present work is presented the performance of 304 stainless steel as forming part of the tubes of a tank that has been operating from 1964 for Liquefied Natura...
Chapter
The Panama Canal, vital to international trade, connects the Pacific Ocean and the Caribbean Sea, through the Gatun inland lake (which is almost entirely freshwater). The canal is now 100 years old. Since 2011, new lanes and locks have been or are being built, which will greatly enhance capacity and accommodate vessels with a much deeper draft. Thi...
Article
La durabilidad de los aceros de alta resistencia en medios agresivos está condicionada por la fragilización por hidrógeno. La fragilización por hidrógeno está presente en muchos de los fallos de estructuras o componentes de acero. En estudios anteriores se ha mostrado el efecto del hidrógeno intersticial dentro de la red de hierro a nivel atómico,...
Chapter
Full-text available
This work is part of the DURACON Ibero-American project, which seeks to characterize concrete durability under environmental conditions, based on reinforced concrete sample exposure in at least two different atmospheres (marine and urban), for each of the 11 countries in the project. Specimens were exposed to the environmental conditions of 13 Mexi...
Article
Concrete quality can be tested on site by coring or non-destructive testing. This paper describes a method based on the four-point or Wenner procedure for measuring electrical resistivity, deployed on a bridge over the River Danube between Vidin, Bulgaria and Calafat, Romania. Due to the high reinforcement density in bridge members, a model had to...
Conference Paper
Full-text available
Hydrogen embrittlement is ubiquitous in many of the failures of steel structures components. The effect of hydrogen inside a periodic lattice of iron has been previously studied at the atomic level concluding that hydrogen does not establish significant chemical bonds with iron; instead it introduces internal stresses that weaken the iron-iron bond...
Chapter
Full-text available
Durability of concrete structures is primarily dependent on the environmental influences, i.e. the penetration of aggressive substances in the structural element from the environment. Penetrability is an important durability indicator of concrete and by specifying different classes of penetrability of concrete it should be possible to design a stru...
Chapter
This chapter presents an overview on several performance-based approaches for concrete durability specification and conformity assessment of the as-built structure.
Article
The kinetics of many reactions important to cement hydration and use are not well understood: this is in part due to the great complexity of many supposedly “simple” processes. One such process, carbonation of portlandite, Ca(OH)2, in moist air at ~ 23 °C has been investigated by microscopy and microchemical analysis. Single crystals of portlandite...
Chapter
Additions to concrete may change some of its basic properties in several ways depending on the nature of these additions. The addition of fibers, in particular, has enabled new concrete characteristics, making standard concrete a very modern composite material. If the fibers are electrical conductors, the properties that change in addition to the m...
Chapter
High strength steels in concrete structures used as reinforcement are usually passivated due to the physical barrier that concrete provides and by a protective passive film developed on the surface by the high alkaline media. Chloride ions can break the passive film. These ions can be found dissolved in the water or in structures in marine environm...
Conference Paper
Full-text available
Hydrogen embrittlement is ubiquitous in many of the failures of steel structures components. The effect of hydrogen inside a periodic lattice of iron has been previously studied at the atomic level concluding that hydrogen does not establish significant chemical bonds with iron; instead it introduces internal stresses that weaken the iron-iron bond...
Article
Chlorides induce local corrosion in the steel reinforcements when reaching the bar surface. The measurement of the rate of ingress of these ions, is made by mathematically fitting the so called “error function equation” into the chloride concentration profile, obtaining so the diffusion coefficient and the chloride concentration at the concrete sur...
Article
Concrete resistivity is a material characteristic that can be related to its durability, as it indicates the amount and tortuosity of the pore network and also informs on the degree of water saturation. Its measurement is usually made in situ by the use of the four-point or Wenner method, but the accuracy of such measurements is affected by the pre...
Article
In this study, the high-strength corrugated steel wire with a diameter of 7.6 mm was subjected to different aerated alkaline mediums (pH8.2, 12.3 and 13.4) with different concentration of Cl−. The electrochemical cell was consisted of a working electrode, an auxiliary electrode and a reference electrode, which was the steel wire, the graphite rod a...
Article
Concrete, together with the steel and reinforced by it, is the most widely used building material. Its site fabrication and diverse performances introduce an enormous variability in its composition and properties. Regarding the embedded reinforcing steel, its alkaline nature provides a protection for hundreds and thousands of years; however, chlori...
Article
Full-text available
RESUMEN El Canal de Panamá fue construido hace unos 100 años y en la actualidad el consorcio “Grupo Unidos por el Canal” (GUPC), coordinado por Sacyr S.A. está construyendo dos nuevas series de esclusas. El hormigón del antiguo Canal no estaba armado pero en el actual se prevé el uso de armadura como parte del diseño antisísmico. La Autoridad del...
Article
Several models have been published to calculate service life of reinforced concrete based on considering diffusion as the main ingress mechanism. However, these models have some limitations and involve destructive and time consuming testing. The authors have developed an alternative model based on electrical resistivity, which is a non-destructive...
Article
Modern concrete has a record of good performance of around 120 years although there are structures in perfect conservation made with roman concrete (mixture of lime and natural pozzolans). El Cabril repository has a design life of 300-500 years and therefore, it should keep its integrity much longer than the back experience we have on reinforced co...
Article
In the present the paper, various tests are described using white and ordinary Portland cement blended with fly ash and a slag to assess their effect on reinforcement corrosion. Natural and accelerated chloride diffusion, carbonation and corrosion tests were performed. The results indicate that the most resistant cement against chloride attack is t...
Article
Full-text available
It is commonly considered that the corrosion of steel in concrete is controlled by the oxygen content of the pore solution and there are service life models that relate the corrosion rate to the amount of oxygen. It is also commonly believed that in water saturated conditions the oxygen content in the pores is negligible and that underwater there i...
Article
RESUMEN Los cálculos de vida útil de las estructuras de hormigón están pasando rápidamente de los laboratorios a las normativas y a ser especificados en la licitación de grandes infraestructuras. Así vidas útiles de 100 años o más se han requerido en puentes como Oresund o en el nuevo canal de Panamá. Sin embargo la especificación se realiza de fo...
Conference Paper
Full-text available
Any number of studies have been conducted in the past to analyse mechanical behaviour of corroded reinforcement steel bars. The general procedure adopted in most studies is threefold: In a first step, rebars are subjected to an accelerated corrosion procedure. Then the corrosion degree, which expresses the material loss of the specimen due to corro...
Article
The RILEM Technical Recommendation intends to give a general description of methods of sampling for obtaining chloride concentration profiles in concrete applicable both for laboratory cast concrete specimens, for concrete cores taken from structures and for testing on site. When sampling one of the most important needs is getting representative sa...
Article
Full-text available
Hydrogen embrittlement is believed to be one of the main reasons for cracking of steel structures under stress and stress corrosion cracking process. To control and prevent the cracking of steel it is necessary to understand the chemical and physical properties of hydrogen inside iron. Usually, pre-stressed steels are high strength steels that incl...
Article
Several models for chloride ingress are being developed in order to calculate service life of the reinforcement. This work presents a numerical solution to approach the behavior of a highly corroded beam in presence of chloride environment during 26 years. In order to make the study, a comparison of the numerical pattern of fracture with the real s...
Article
Chloride threshold for reinforcement corrosion has been found to be very variable in function of several material and environmental characteristics. Regarding carbonation, the corrosion onset is associated to the arrival to the rebar of the carbonation front. In both cases it is usually neglected in the calculations the geometrical fact of consider...
Article
Full-text available
There are many approaches that are made regarding the status of these nuclear structures and the possibility of extending its service life, being corrosion one of the problems that most concern today. Therefore, the corrosion control and evaluation in structures such as the liners of the contention buildings is extremely important to assure that th...
Article
The corrosion of reinforcement can be detected and its evolution quantified through the polarization resistance, Rp, which enables to calculate the instantaneous corrosion rate. In large structures, the determination of the Rp method uses a small counter electrode and the current applied attenuates with the distance, which makes unknown the area po...
Article
In marine environments, reinforcement corrosion develops due to the penetration of chlorides through the concrete pores. Initially the corrosion appears as localized attack, but when the chlorides arrive in high quantities, it extends to the bar surfaces which corrode entirely. In numerous previous studies, the detection of corrosion and its evolut...
Article
Concrete protects the steel embedded until carbonation front or the chloride threshold reaches the rebar. Then a corrosion process develops. In present paper the corrosion process is analyzed from its onset a definition of which is given. The techniques for its measurement are described and also are given a model for the corrosion propagation perio...
Article
It is commonly mentioned that in concrete chloride induced corrosion is controlled by the oxygen content in such a manner that in water saturated conditions no oxygen will be present and thus no corrosion can develop. In the present paper, experimentation has been made in low oxygen availability "pore" solutions with several amounts of chlorides. T...
Article
We have used Ab initio calculations to study the structural changes produced by the inclusion of light impurities into pure bcc iron. In order to obtain a clear picture of the mechanics of the phase changes Bain's pathway was studied in detail for pure iron. The position that hydrogen atoms tend to occupy at high densities favours octahedral sites...
Article
In field structures affected by fire, the temperature progress through the material. The progression of temperature in the concrete material can be determined by simultaneous differential thermal analysis and thermogravimetry. Also, the analysis of the behaviour of concrete in real concrete, by different techniques, permits the corroboration of the...
Article
The hydration process of the cements induces the formation of different kinds of hydration products. The main products of hydration are C–S–H gel and portlandite [Ca(OH)2]. The C–S–H gel is an amorphous compound that is discomposed progressivity with the temperature until approximately 1,000 °C, while the portlandite is discomposed between 450 and...
Article
Cement paste carbonation, i.e., the reaction between CO2 and the hydrated cement phases, mainly calcium hydroxide or portlandite, can lead to a pH decrease, which in turn can give rise to steel corrosion in reinforced concrete. At the same time, the carbonation reaction contributes to combine CO2 and fix it as calcium carbonate. It is a crucial phe...
Article
Corrosion is one of the major durability problems that needs to be solve in order to extend the service life of a reinforced concrete structure. Within the APPLET project, in order to evaluate corrosion kinetics, the influences of both the concrete (sound or polluted) and the environmental conditions (controlled or outdoor) were studied. Four serie...
Article
A conditioning procedure is proposed allowing to install into the concrete specimens any selected value of water saturation degree with homogeneous moisture distribution. This is achieved within the least time and the minimum alteration of the concrete specimens. The protocol has the following steps: obtaining basic drying data at 50 °C (water abso...
Article
In spite of the numerous studies carried out on carbonation of the concrete, very few data have been published on the mechanism of steel depassivation and the corrosion rates involved in this type of phenomenon. Also some uncertainties remain as to the chemical composition of the pore solution of a carbonated concrete. Random behaviours related wit...
Article
Reinforcement corrosion is one of the major durability problems that need to be solved in order to extend the service life of a structure. It is influenced, on one hand, by the concrete itself, sound or polluted (chlorinated or carbonated), and on the other hand, by the environmental conditions (controlled or outdoor). To explore the influence of t...
Article
The inexistence of quantitative data on steel behaviour in carbonated mortar and concrete have driven us to carry out a serie of tests to know the kinetic of the corrosion rebars. Polarization Resistance was the technique used to determine the corrosion rate of the rebars. In the present tests a first study with mortar has been carried out to know...
Conference Paper
Full-text available
Una de las consecuencias de la corrosión de las armaduras, y quizás la menos estudiada, es la pérdida de las propiedades mecánicas en general, y de la ductilidad en particular. Existen diversos estudios experimentales en los que se han realizado ensayos de tracción a barras después de haber sido expuestas a diversos procesos de corrosión. Sin embar...
Article
Full-text available
The present work deals with the carbonation process in cement based materials such as concrete. In order to clarify the evolution of the two main phases involved in the process, portlandite and calcium carbonate as a function of depth, spatially resolved neutron diffraction experiments have been performed at SALSA diffractometer at ILL in carbonate...
Article
Calcium carbonate decomposes under well-defined conditions giving CaO (solid) and CO2 (gas). The process kinetics are known to be strongly influenced by the CO2 partial pressure and temperature. In dynamic conditions, as in thermogravimetric analysis (TG) and differential thermal analysis (DTA), kinetics influence the observed heat effect and mass...
Article
Full-text available
In this work the dielectric properties of concrete with and without chlorides as a function of their water contents were studied by the Electrical Impedance Spectroscopy (EIS). Specimens of cement paste with different water/cement ratio and chlorides content was analyzed. After drying the specimens, the rehydratation was controled by the relative w...
Article
Full-text available
Present paper describes some aspects of the restoration project recently undertaken in La Zarzuela Racecourse, designed by E. Torroja, Despite the good mechanical work of steel, it has started a deterioration process which has caused the reinforcement corrosion by carbonation. It has been detected corrosion attack in some places due the breaking of...
Article
Measurements of corrosion rate of reinforcing steels have been carried out in solutions simulating electrolytic chloride environments in corrosion pits in the propagation period with sodium nitrite. A significant corrosion inhibition has been observed at relatively low chloride contents of 0.045M due to the presence of nitrite in these systems, but...
Article
Full-text available
The effect of humidity on hydrated cement carbonation has been studied by means of in-situ neutron diffraction measurements. The evolution of the main crystalline phases in the bulk of the sample, portlandite and calcite, has been monitored during the process. Data obtained from neutron diffraction allow the quantification of the phases involved. T...
Article
The experimental conditions for corrosion rate measurements of reinforcement by means of the polarization resistance technique, Rp, in order to obtain reliable values (in accordance with the gravimetric losses simultaneously measured) must consider some factors as are: the need to subtract ohmic drop generated by the high resistivity of the concret...
Article
When chloride-induced corrosion takes place, a local acidification occurs at the corrosion pit. Therefore, it is necessary to study the performance of corrosion inhibitors in low-pH environments. Reinforcing steel bars have been exposed to solutions that simulate the electrolytic environment of concrete micropores during the corrosion propagation p...
Article
La necesidad de calcular la durabilidad del hormigón ha llevado a buscar un ensayo que fuera capaz de cuantificar todas las fases del proceso desde la fabricación del hormigón hasta su curado y endurecimiento. La resistividad eléctrica como inversa de la conductividad-difusividad es una propiedad del hormigón que permite su control de forma no dest...
Article
Most of the low-level nuclear waste disposal facilities are based in engineered multi barrier systems where reinforced concrete is one of the basic materials. The calculation of the time until steel reinforcement depassivation is a need due to the demand of prediction of the service life of concrete structures in radioactive repositories. In doing...
Article
Full-text available
The generic design of the centralised spent fuel storage facility was approved by the Spanish Safety Authority in 2006. The planned operational life is 60 years, while the design service life is 100 years. Durability studies and surveillance of the behaviour have been considered from the initial design steps, taking into account the accessibility l...
Article
In order to study the real on-site aging of concrete and the potential corrosion risk for the reinforcements, Enresa has undertaken a monitoring programme in collaboration with Institute of Construction Science ‘Eduardo Torroja’ (IETcc) by permanently monitoring a pilot nuclear waste container through the installation of sensors. The pilot containe...
Article
The steel industry generates a substantial quantity of waste, the so called electric arc furnace dust (EAFD). The chemical composition of this dust varies even for the same factory from one batch to another, but in all cases, this dust contains hazardous metals, and in some cases, it contains other species such as chloride ions. In addition to the...
Chapter
Full-text available
The stress corrosion cracking process is at this moment an unknown mechanism of deterioration. It is a process that implies the joint action of the media, the presence of corrosion or a surface defect and of stress in the metal. Prestressing tendons can suffer SCC jointly with hydrogen embrittlement which dramatically changes not only the type of f...
Article
A recently proposed methodology for measuring the diffusion coefficient of chloride ions through concrete partially saturated with water, has been applied to five high-early-strength Portland cement mortars. The method is based on putting solid NaCl in contact with the concrete surface during the diffusion test. The results obtained indicate a stro...
Article
The electrochemical techniques used to measure metallic corrosion rely on making a direct electrical contact to the working electrode. The inductive or non-contacting method is based in the application of an external electrical signal that does not need to make physical contact to the metal to polarize it. In previous papers, its feasibility has be...
Article
The oxide formed during corrosion has an expansive character which induces the cracking of concrete cover. The properties of this oxide layer are focussing the interest due the need to introduce its mechanical characteristics in the models to calculate crack width. In a previous paper it was suggested that the oxide behave as “water” and in consequ...
Article
Reinforcement corrosion induces several structural damages which affect the serviceability and the safety of concrete structures. The use of sensors can help to control and optimize the life cycle and indicate the best time to undertake repair at the lower cost. However, results are scarce on the interpretation of the values obtained due the diffic...
Article
El Prado Museum in Madrid has been recently submitted to a refurbishment of its roof which from been made with the traditional tiles has been changed to the use of modern waterproofing layers covered with a metallic lead finishing. Due to an unexpected damp patch that produced leaking in the hall in which Las Meninas by Velázquez was exhibited, the...
Article
Durability of concrete structures under marine environments has been studied for a long time. This work was focused on marine atmosphere zone and studied the deposition of chlorides on wet candle devices and its relation with chlorides accumulated into concrete. Concrete specimens with three different mixtures were exposed at places located at four...
Chapter
The importance in real structures of an accurate identification of the zones suffering corrosion, and the determination of the actual loss in cross-section in these zones and the rate of its progress is recognized. Although there exist several techniques used on-site for characterizing corrosion of reinforcements, the most appropriate are those of...
Article
Electrokinetic effects are those that take place by application of an electric field to porous materials, with the zeta potential as the key parameter. Specifically, in the case of contaminated construction materials, the generation of an electroosmotic flux, with the corresponding dragging due to water transport, is a crucial mechanism to succeed...