The present study examines the behavior of three major categories of organic coatings which are applied on the surface of concrete structures and specifically conventional, high performance and nanotechnology paint sy...The present study examines the behavior of three major categories of organic coatings which are applied on the surface of concrete structures and specifically conventional, high performance and nanotechnology paint systems. The comparison is achieved in the means of anticorrosion properties under the presence of chloride ions and carbonation resistance. The evaluation methods included electrochemical measurements in order to assess corrosion properties and the determination of steel’s mass loss after the end of the experimental procedure. Carbonation depth was measured using phenolphthalein as indicator after accelerated and physical exposure. From the results so far it can be shown nanocoatings gave promising results regarding induced chloride ion corrosion.展开更多
The objective of this paper is to investigate the behaviour of amino alcohol corrosion inhibitors when they are used in reinforced cement mortars either as admixtures in the cement paste or as coating applications on ...The objective of this paper is to investigate the behaviour of amino alcohol corrosion inhibitors when they are used in reinforced cement mortars either as admixtures in the cement paste or as coating applications on the surface of the rebars. The reinforced cement mortars were exposed to both partial and full immersion in 3.5 wt% NaCl solution. Electrochemical measurements such as half-cell potential and linear polarization technique, as well as weight loss of the embedded rebars were performed in order to obtain information on the corrosion behaviour of the reinforcing steel in cement mortar. Results demonstrate that the amino alcohol corrosion inhibitors offer protection against rebar corrosion in cement mortars.展开更多
Corrosion of reinforced concrete is the most important cause of concrete structure deterioration. In the present study, the protective effect of the reinforcement mortars against corrosion is examined. In particular, ...Corrosion of reinforced concrete is the most important cause of concrete structure deterioration. In the present study, the protective effect of the reinforcement mortars against corrosion is examined. In particular, the chloride penetration resistance on reinforced cement mortars using organic coating as additive containing was studied. The aforementioned additive consists of corrosion inhibitor for protection of steel rebars against pitting corrosion. For the experimental procedure, four (4) different types of reinforced mortars were prepared. The corrosion protection of the additive was evaluated by electrochemical methods, (linear polarization resistance, Half-cell Potential Resistance and Electrochemical Impedance Spectroscopy). In addition, the mass loss of steel rebars against time of partially immersed in NaCl solution was carried out in the lab. The experimental results showed that in all examined cases the organic coating provides anticorrosion protection on steel rebars against chlorides.展开更多
This paper examines the use of corrosion inhibitors in order to protect the reinforcement of concrete. For this purpose mortar specimens were constructed with or without corrosion inhibitors and were partially immerse...This paper examines the use of corrosion inhibitors in order to protect the reinforcement of concrete. For this purpose mortar specimens were constructed with or without corrosion inhibitors and were partially immersed in sodium chloride. Corrosion inhibitors were used as admixture into concrete and were sprayed on the external surface of mortar specimens. In all mortar specimens, electric junction between reinforcements was achieved. The methods that were used for the evaluation of the reinforcement corrosion in concrete, included half-cell potential measurements, polarization curves of reinforced rebars and mass loss of the reinforcement. Finally, the durability of concrete after the use of corrosion inhibitors was also examined.展开更多
Although reinforced concrete structures are able to withstand towards a variety of adverse environmental conditions, reinforcement corrosion could lead to concrete structure deterioration. The present study examines f...Although reinforced concrete structures are able to withstand towards a variety of adverse environmental conditions, reinforcement corrosion could lead to concrete structure deterioration. The present study examines four different ways of using corrosion inhibitors against pitting corrosion. In particular, it was investigated the chloride penetration resistance of reinforced cement mortars using corrosion inhibitor applied in three different ways. The corrosion behavior of the specimens was evaluated by electrochemical methods such as Linear Polarization Resistance and Halfcell Potential Resistance. In addition, the mass loss of steel rebars against time of partially immersion in sodium chloride (NaCl) solution was carried out in the lab. The experimental results showed that the corrosion systems examined in the study provide anticorrosion protection on steel rebars against chlorides comparing with the reference group.展开更多
The deterioration of concrete over time is the result of various mechanical, physical, chemical and biological processes, with the corrosion of reinforcement being the most serious problem of durability of reinforced ...The deterioration of concrete over time is the result of various mechanical, physical, chemical and biological processes, with the corrosion of reinforcement being the most serious problem of durability of reinforced concrete structures. Over the last 50 years, a tremendous effort has been spent by the international scientific community with laboratory research and experimental field studies in order to increase the resistance of concrete over corrosion. This paper presents an experimental study of the corrosion behavior of 5 different concrete mix designs. The compositions were developed as per the latest concrete regulations and International Standards which are as follows: conventional concrete C30/37, conventional concrete with corrosion inhibitor as an additive, conventional concrete with surface spray sealant, fine aggregate concrete and self-compacting concrete. Their behavior against corrosion was determined via the following tests: water absorption test, water permeability test, mercury intrusion porosimetry, rapid chloride penetration test (RCPT), and accelerated carbonation test. The experimental results showed that the corrosion systems examined in the study provide anti-corrosion protection on steel rebars against corrosion comparing with the reference group. Also, an inversely proportional relationship of the water/cement ratio of a composition with its corrosion behavior was observed. Smaller w/c values (0.4 instead of 0.5) lead to better anti-corrosion resistance. In addition, an analogous relationship between the cement content of a composition and its corrosion behavior was observed.展开更多
The deterioration of concrete over time is the result of various mechanical, physical, chemical and biological processes, with the corrosion of reinforcement being the most serious problem of durability of reinforced ...The deterioration of concrete over time is the result of various mechanical, physical, chemical and biological processes, with the corrosion of reinforcement being the most serious problem of durability of reinforced concrete structures. Over the last 50 years, a tremendous effort has been spent by the international scientific community with laboratory research and experimental field studies in order to increase the resistance of concrete over corrosion. This paper presents an experimental study of the corrosion behaviour of reinforced concrete beams with simultaneous sustained flexural loading. For this purpose, 40 reinforced concrete beams of 5 different compositions were constructed and exposed in simulated harmful environmental conditions in 3 different stress ratios for a total period of 42 months. Their behavior against corrosion was determined via regular measurements of the electrical resistance of concrete (according to ASTM G57) and the corrosion potential of the steel-reinforced bars with the use of copper sulphate (CSE) as reference electrode (according to ASTM C876). A theoretical calculation of the corrosion rate was conducted based on the electrochemical measurements of the beams. The results indicate that the corrosion potential of steel decreased in time and more rapidly after the initiation of the corrosion process;the electrical resistance firstly increased, remained stable for a short period and then decreased with the corrosion development, as expected. An inversely proportional relationship of the water/cement ratio of a composition with its corrosion behaviour as well as an analogous relationship between the cement content of a composition and its corrosion behaviour was observed. Also, the corrosion rate of steel is increased gradually with increasing load.展开更多
The aim of this study is to examine the performance of nano additives in two different sets of mortar specimens armed with reinforcing steel rebars. In particular, three sets of reinforced concrete cylinders with addi...The aim of this study is to examine the performance of nano additives in two different sets of mortar specimens armed with reinforcing steel rebars. In particular, three sets of reinforced concrete cylinders with additives of 0.1% wt of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have been exposed to a solution of 3.5% NaCl, and further examined for the impact of nano-modification on corrosion performance. The anti-corrosive performance of these additives was investigated through linear polarization technique (LPR), mass loss and mercury porosimetry technique (MIP). From the investigation results, it is found that the addition of CNTs/CNFs causes lower steel corrosion, whereas the pore structure of concrete with CNTs/CNFs can significantly reduce the mass loss rate and the relative permeability.展开更多
Following the evolution of currently enforced Performance Based Design standards of reinforced concrete (RC) structures for durability, the designer, rather than complying with given prescriptive limits, may instead s...Following the evolution of currently enforced Performance Based Design standards of reinforced concrete (RC) structures for durability, the designer, rather than complying with given prescriptive limits, may instead specify a cementitious mix design that is proven to exhibit a code prescribed resistance level (class) to a given exposure environment. Such compliance will lead to the protection of the steel reinforcement from corrosion and the cementitious mortar from degradation, during the design lifespan of the structure, under aggressive environmental exposure conditions such as, marine or deicing salts and carbonation. In this context, the enhancement of the physical and durability properties of common cement-based mortars under chloride exposure are experimentally investigated herein. In particular, the experimental program reported herein aims to evaluate the influence of incorporating multi-walled carbon nanotubes on the physical and mechanical properties of reinforced mortars against chloride ions. Furthermore, the anticorrosion protection of cementitious composites prepared with nanomaterials at 0.2% w/w is further investigated, by comparing all test results against reference specimens prepared without any additive. Electrochemical (Half-cell potential, corrosion current) and mass loss of reinforcement steel measurements were performed, while the porosity, capillary absorption and flexural strength were measured to evaluate the mechanical and durability characteristics of the mortars, following a period of exposure of eleven months;SEM images coupled with EDX analysis were further recorded and used for microstructure observation. The test results indicate that the inclusion of the nanomaterials in the mix improved the durability of the mortar specimens, while the nano-modified composites exhibited higher chloride penetration resistance and flexural strength than the corresponding values of the reference mortars. The test results and the comparison between nanomodified and reference mortars showed that the use of CNTs as addition led to protection of steel reinforcing bars against pitting corrosion and a significant improvement in flexural strength and porosity of the mortars.展开更多
In this paper examines the improving durability of different limestone cement and effects of the use of corrosion inhibitor. The target is to experimentally investigate the effect of different types of cement in corro...In this paper examines the improving durability of different limestone cement and effects of the use of corrosion inhibitor. The target is to experimentally investigate the effect of different types of cement in corrosion of reinforcement in presents of corrosion inhibitors and without it. Three types of cement have been used: CEM II, LC1 and LC2. For this purpose constructed mortar specimens, containing 4 reinforcements, with or without corrosion inhibitors for each group, these exhibited to partial immersion in sodium chloride in 3.5% w.t NaCl solution. The methods, with which the corrosion of reinforcement in concrete was tested, were measurements of corrosion potential, corrosion current and mass loss of reinforcement. The mortars with CEM II cement have better durability than that with limestone cement. The use of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with CEM II cement upper 50%. On the other hand, the addition of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with limestone cement 30% or lower.展开更多
文摘The present study examines the behavior of three major categories of organic coatings which are applied on the surface of concrete structures and specifically conventional, high performance and nanotechnology paint systems. The comparison is achieved in the means of anticorrosion properties under the presence of chloride ions and carbonation resistance. The evaluation methods included electrochemical measurements in order to assess corrosion properties and the determination of steel’s mass loss after the end of the experimental procedure. Carbonation depth was measured using phenolphthalein as indicator after accelerated and physical exposure. From the results so far it can be shown nanocoatings gave promising results regarding induced chloride ion corrosion.
文摘The objective of this paper is to investigate the behaviour of amino alcohol corrosion inhibitors when they are used in reinforced cement mortars either as admixtures in the cement paste or as coating applications on the surface of the rebars. The reinforced cement mortars were exposed to both partial and full immersion in 3.5 wt% NaCl solution. Electrochemical measurements such as half-cell potential and linear polarization technique, as well as weight loss of the embedded rebars were performed in order to obtain information on the corrosion behaviour of the reinforcing steel in cement mortar. Results demonstrate that the amino alcohol corrosion inhibitors offer protection against rebar corrosion in cement mortars.
文摘Corrosion of reinforced concrete is the most important cause of concrete structure deterioration. In the present study, the protective effect of the reinforcement mortars against corrosion is examined. In particular, the chloride penetration resistance on reinforced cement mortars using organic coating as additive containing was studied. The aforementioned additive consists of corrosion inhibitor for protection of steel rebars against pitting corrosion. For the experimental procedure, four (4) different types of reinforced mortars were prepared. The corrosion protection of the additive was evaluated by electrochemical methods, (linear polarization resistance, Half-cell Potential Resistance and Electrochemical Impedance Spectroscopy). In addition, the mass loss of steel rebars against time of partially immersed in NaCl solution was carried out in the lab. The experimental results showed that in all examined cases the organic coating provides anticorrosion protection on steel rebars against chlorides.
文摘This paper examines the use of corrosion inhibitors in order to protect the reinforcement of concrete. For this purpose mortar specimens were constructed with or without corrosion inhibitors and were partially immersed in sodium chloride. Corrosion inhibitors were used as admixture into concrete and were sprayed on the external surface of mortar specimens. In all mortar specimens, electric junction between reinforcements was achieved. The methods that were used for the evaluation of the reinforcement corrosion in concrete, included half-cell potential measurements, polarization curves of reinforced rebars and mass loss of the reinforcement. Finally, the durability of concrete after the use of corrosion inhibitors was also examined.
文摘Although reinforced concrete structures are able to withstand towards a variety of adverse environmental conditions, reinforcement corrosion could lead to concrete structure deterioration. The present study examines four different ways of using corrosion inhibitors against pitting corrosion. In particular, it was investigated the chloride penetration resistance of reinforced cement mortars using corrosion inhibitor applied in three different ways. The corrosion behavior of the specimens was evaluated by electrochemical methods such as Linear Polarization Resistance and Halfcell Potential Resistance. In addition, the mass loss of steel rebars against time of partially immersion in sodium chloride (NaCl) solution was carried out in the lab. The experimental results showed that the corrosion systems examined in the study provide anticorrosion protection on steel rebars against chlorides comparing with the reference group.
文摘The deterioration of concrete over time is the result of various mechanical, physical, chemical and biological processes, with the corrosion of reinforcement being the most serious problem of durability of reinforced concrete structures. Over the last 50 years, a tremendous effort has been spent by the international scientific community with laboratory research and experimental field studies in order to increase the resistance of concrete over corrosion. This paper presents an experimental study of the corrosion behavior of 5 different concrete mix designs. The compositions were developed as per the latest concrete regulations and International Standards which are as follows: conventional concrete C30/37, conventional concrete with corrosion inhibitor as an additive, conventional concrete with surface spray sealant, fine aggregate concrete and self-compacting concrete. Their behavior against corrosion was determined via the following tests: water absorption test, water permeability test, mercury intrusion porosimetry, rapid chloride penetration test (RCPT), and accelerated carbonation test. The experimental results showed that the corrosion systems examined in the study provide anti-corrosion protection on steel rebars against corrosion comparing with the reference group. Also, an inversely proportional relationship of the water/cement ratio of a composition with its corrosion behavior was observed. Smaller w/c values (0.4 instead of 0.5) lead to better anti-corrosion resistance. In addition, an analogous relationship between the cement content of a composition and its corrosion behavior was observed.
文摘The deterioration of concrete over time is the result of various mechanical, physical, chemical and biological processes, with the corrosion of reinforcement being the most serious problem of durability of reinforced concrete structures. Over the last 50 years, a tremendous effort has been spent by the international scientific community with laboratory research and experimental field studies in order to increase the resistance of concrete over corrosion. This paper presents an experimental study of the corrosion behaviour of reinforced concrete beams with simultaneous sustained flexural loading. For this purpose, 40 reinforced concrete beams of 5 different compositions were constructed and exposed in simulated harmful environmental conditions in 3 different stress ratios for a total period of 42 months. Their behavior against corrosion was determined via regular measurements of the electrical resistance of concrete (according to ASTM G57) and the corrosion potential of the steel-reinforced bars with the use of copper sulphate (CSE) as reference electrode (according to ASTM C876). A theoretical calculation of the corrosion rate was conducted based on the electrochemical measurements of the beams. The results indicate that the corrosion potential of steel decreased in time and more rapidly after the initiation of the corrosion process;the electrical resistance firstly increased, remained stable for a short period and then decreased with the corrosion development, as expected. An inversely proportional relationship of the water/cement ratio of a composition with its corrosion behaviour as well as an analogous relationship between the cement content of a composition and its corrosion behaviour was observed. Also, the corrosion rate of steel is increased gradually with increasing load.
文摘The aim of this study is to examine the performance of nano additives in two different sets of mortar specimens armed with reinforcing steel rebars. In particular, three sets of reinforced concrete cylinders with additives of 0.1% wt of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have been exposed to a solution of 3.5% NaCl, and further examined for the impact of nano-modification on corrosion performance. The anti-corrosive performance of these additives was investigated through linear polarization technique (LPR), mass loss and mercury porosimetry technique (MIP). From the investigation results, it is found that the addition of CNTs/CNFs causes lower steel corrosion, whereas the pore structure of concrete with CNTs/CNFs can significantly reduce the mass loss rate and the relative permeability.
文摘Following the evolution of currently enforced Performance Based Design standards of reinforced concrete (RC) structures for durability, the designer, rather than complying with given prescriptive limits, may instead specify a cementitious mix design that is proven to exhibit a code prescribed resistance level (class) to a given exposure environment. Such compliance will lead to the protection of the steel reinforcement from corrosion and the cementitious mortar from degradation, during the design lifespan of the structure, under aggressive environmental exposure conditions such as, marine or deicing salts and carbonation. In this context, the enhancement of the physical and durability properties of common cement-based mortars under chloride exposure are experimentally investigated herein. In particular, the experimental program reported herein aims to evaluate the influence of incorporating multi-walled carbon nanotubes on the physical and mechanical properties of reinforced mortars against chloride ions. Furthermore, the anticorrosion protection of cementitious composites prepared with nanomaterials at 0.2% w/w is further investigated, by comparing all test results against reference specimens prepared without any additive. Electrochemical (Half-cell potential, corrosion current) and mass loss of reinforcement steel measurements were performed, while the porosity, capillary absorption and flexural strength were measured to evaluate the mechanical and durability characteristics of the mortars, following a period of exposure of eleven months;SEM images coupled with EDX analysis were further recorded and used for microstructure observation. The test results indicate that the inclusion of the nanomaterials in the mix improved the durability of the mortar specimens, while the nano-modified composites exhibited higher chloride penetration resistance and flexural strength than the corresponding values of the reference mortars. The test results and the comparison between nanomodified and reference mortars showed that the use of CNTs as addition led to protection of steel reinforcing bars against pitting corrosion and a significant improvement in flexural strength and porosity of the mortars.
文摘In this paper examines the improving durability of different limestone cement and effects of the use of corrosion inhibitor. The target is to experimentally investigate the effect of different types of cement in corrosion of reinforcement in presents of corrosion inhibitors and without it. Three types of cement have been used: CEM II, LC1 and LC2. For this purpose constructed mortar specimens, containing 4 reinforcements, with or without corrosion inhibitors for each group, these exhibited to partial immersion in sodium chloride in 3.5% w.t NaCl solution. The methods, with which the corrosion of reinforcement in concrete was tested, were measurements of corrosion potential, corrosion current and mass loss of reinforcement. The mortars with CEM II cement have better durability than that with limestone cement. The use of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with CEM II cement upper 50%. On the other hand, the addition of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with limestone cement 30% or lower.
