{"title":"Dispersion Mechanisms of Alite Stabilized by Superplasticizers Containing Polyethylene Oxide Graft Chains","authors":"E. Sakai, M. Daimon","doi":"10.14359/6184","DOIUrl":"https://doi.org/10.14359/6184","url":null,"abstract":"","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74942503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Coppola, R. Troli, A. Borsoi, P. Zaffaroni, M. Collepardi
Reactive powder mortar (RPM) mixtures cured at room temperature with different portland cement, silica fume and steel fibers were manufactured. The influence of the superplasticizer type on the ROM performance - in terms of w/c and compressive strength - was studied. The acrylic polymer (AP) admixture performed better than the naphthalene (SNF) or melamine (SMF) based superplasticizers in regard to lower water-cement ratio and higher compressive strength at ages after 3 days. The 1-day compressive strength of the RPM with the AP admixture was much lower than that of the corresponding mixtures with SNF or SMF with C3a-free portland cement with a low specific surface are was used. This was due to a strong retarding effect of the early hydration when this cement was used in combination with some silica fume types. With other portland cements, the retarding in the early hydration caused by AP did not occur and therefore the 1-day compressive strength was quite high. The 28-day compressive strength of RPM specimens, cured at room temperature, were strongly dependent on the type of cement, silica fume and superplasticizer. However, the highest values obtained in this investigation (160-180 Mpa) were lower than those reported by the inventors of RPM (170-230 Mpa).
{"title":"Influence of Superplasticizer Type on the Compresive Strength of Reactive Powder Mortars","authors":"L. Coppola, R. Troli, A. Borsoi, P. Zaffaroni, M. Collepardi","doi":"10.14359/6201","DOIUrl":"https://doi.org/10.14359/6201","url":null,"abstract":"Reactive powder mortar (RPM) mixtures cured at room temperature with different portland cement, silica fume and steel fibers were manufactured. The influence of the superplasticizer type on the ROM performance - in terms of w/c and compressive strength - was studied. The acrylic polymer (AP) admixture performed better than the naphthalene (SNF) or melamine (SMF) based superplasticizers in regard to lower water-cement ratio and higher compressive strength at ages after 3 days. The 1-day compressive strength of the RPM with the AP admixture was much lower than that of the corresponding mixtures with SNF or SMF with C3a-free portland cement with a low specific surface are was used. This was due to a strong retarding effect of the early hydration when this cement was used in combination with some silica fume types. With other portland cements, the retarding in the early hydration caused by AP did not occur and therefore the 1-day compressive strength was quite high. The 28-day compressive strength of RPM specimens, cured at room temperature, were strongly dependent on the type of cement, silica fume and superplasticizer. However, the highest values obtained in this investigation (160-180 Mpa) were lower than those reported by the inventors of RPM (170-230 Mpa).","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75088489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This project has shown that it is possible to make concrete with low-heat and high-strength by properly exploiting the potentials of the materials used. The high-range water-reducing air-entraining agent (AE) used played an important role. However, there was a need to reduce the slump loss. A new high-range water-reducing AE agent was developed for this purpose. The agent is a compound of a polycarboxylate type copolymer and a special polymeric surface active agent. This paper describes strength and heat properties of concrete with the developed agent. A moderate heat portland cement and a super-ground granulated blast-furnace slag were used. The test results showed that the newly-developed high-range water-reducing AE agent makes it possible to reduce the slump loss of concrete without losing the properties of low-heat and high-strength. However, it was found that the low-heat property of the developed concrete is lost when the concrete is proportioned to be flowable.
{"title":"Slump-Loss Improvement of Low-Heat High-Strength Concrete","authors":"K. Sakai, H. Watanabe, M. Kinoshita","doi":"10.14359/6189","DOIUrl":"https://doi.org/10.14359/6189","url":null,"abstract":"This project has shown that it is possible to make concrete with low-heat and high-strength by properly exploiting the potentials of the materials used. The high-range water-reducing air-entraining agent (AE) used played an important role. However, there was a need to reduce the slump loss. A new high-range water-reducing AE agent was developed for this purpose. The agent is a compound of a polycarboxylate type copolymer and a special polymeric surface active agent. This paper describes strength and heat properties of concrete with the developed agent. A moderate heat portland cement and a super-ground granulated blast-furnace slag were used. The test results showed that the newly-developed high-range water-reducing AE agent makes it possible to reduce the slump loss of concrete without losing the properties of low-heat and high-strength. However, it was found that the low-heat property of the developed concrete is lost when the concrete is proportioned to be flowable.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79526140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Different superplasticizers have been tested in order to evaluate their effect on concrete properties and to express concrete's rheology in fundamental parameters such as yield stress and plastic viscosity. Measurements were made on concrete's rheology with two different viscometers, once for mortar and one for results from slump tests at different times after mixing, slump loses by means of time required to lose 30 mm of slump and time required to lose half the initial slump value were calculated. The time necessary before trowelling was also measured. Results show that viscosity-measurements on mortar give useful information about the fresh concrete's properties, information that cannot be attained with the traditional methods, such as slump, spread, etc. The method of evaluating trowelling hardness very efficiently measures the admixture's effect on retardation. Only those superplasticizers containing new types of acrylic and vinyl polymers show effects efficient enough to belong to the second generation.
{"title":"Effects of a New Generation of Superplasticizers on the Properties of Fresh Concrete","authors":"J. Norberg, Peterson, P. Norberg, P. Billberg","doi":"10.14359/6203","DOIUrl":"https://doi.org/10.14359/6203","url":null,"abstract":"Different superplasticizers have been tested in order to evaluate their effect on concrete properties and to express concrete's rheology in fundamental parameters such as yield stress and plastic viscosity. Measurements were made on concrete's rheology with two different viscometers, once for mortar and one for results from slump tests at different times after mixing, slump loses by means of time required to lose 30 mm of slump and time required to lose half the initial slump value were calculated. The time necessary before trowelling was also measured. Results show that viscosity-measurements on mortar give useful information about the fresh concrete's properties, information that cannot be attained with the traditional methods, such as slump, spread, etc. The method of evaluating trowelling hardness very efficiently measures the admixture's effect on retardation. Only those superplasticizers containing new types of acrylic and vinyl polymers show effects efficient enough to belong to the second generation.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88568994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fluidity of self compacting concrete is influenced by the fluidity of the composed mortar. This paper discusses the rheological estimation of the fluidity of high-flowing mortars with superplasticizers. The character of fine aggregates is considered the most effective factor on mortar fluidity. The applicability of the viscosity equation proposed by Mori and Ototake for condensed suspension liquids to highly-flowing mortar is discussed. Mortars were tested with different volume concentration of fine aggregate-suspended in highly-flowing paste. The result from rheological test using a Brookfield type viscometer indicated good agreement with the equation. Provided that the fluidity of the mortar behaves as a Bingham fluid, it can be estimated by plastic viscosity and yield value. These rheological tests were applied to two types of highly-flowing mortars composed of self compacting concrete mixtures ranging from 60 to 70 cm of slumping flow value. The effects of fine aggregate fluctuated with differences in water content, sand content and sand grading of the basic mortar. Test results showed that the character of the sand remarkably affects the fluidity of highly-flowing mortar.
{"title":"Rheological Estimation of Flowing Mortar with a Superplasticizer","authors":"S. Kakuta","doi":"10.14359/6195","DOIUrl":"https://doi.org/10.14359/6195","url":null,"abstract":"The fluidity of self compacting concrete is influenced by the fluidity of the composed mortar. This paper discusses the rheological estimation of the fluidity of high-flowing mortars with superplasticizers. The character of fine aggregates is considered the most effective factor on mortar fluidity. The applicability of the viscosity equation proposed by Mori and Ototake for condensed suspension liquids to highly-flowing mortar is discussed. Mortars were tested with different volume concentration of fine aggregate-suspended in highly-flowing paste. The result from rheological test using a Brookfield type viscometer indicated good agreement with the equation. Provided that the fluidity of the mortar behaves as a Bingham fluid, it can be estimated by plastic viscosity and yield value. These rheological tests were applied to two types of highly-flowing mortars composed of self compacting concrete mixtures ranging from 60 to 70 cm of slumping flow value. The effects of fine aggregate fluctuated with differences in water content, sand content and sand grading of the basic mortar. Test results showed that the character of the sand remarkably affects the fluidity of highly-flowing mortar.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82501168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seven different polymer latexes, characterized by different resistance to alkaline hydrolysis, were used to produce polymer-modified cement mortars. The following polymers were tested: styrene-butadiene copolymer, vinyl acetate-vinyl versatate copolymer, vinyl acetate-vinyl versatates terpolymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl propionate copolymer, vinyl acetate-dibutyl maleate copolymer and vinyl acetate homopolymer. Measurements of compressive strength, dynamic modulus of elasticity, water absorption and bond-strength to a concrete substrate were carried out on the polymer-modified mortars in comparison to a reference mixture without polymers. Infrared and XRD analytical techniques were used to investigate the alkaline hydrolysis of the polymers and cement hydration, respectively. The results indicate that polymers with higher resistance to hydrolysis performed better in terms of higher bond strength to the concrete substrate and lower water absorption of the corresponding mortars.
{"title":"The Influence of Vinyl Polymers on the Characteristics of Polymer-Modified Mortars","authors":"R. Arcozzi, G. Ferrari, L. Gini, G. Pistolesi","doi":"10.14359/6183","DOIUrl":"https://doi.org/10.14359/6183","url":null,"abstract":"Seven different polymer latexes, characterized by different resistance to alkaline hydrolysis, were used to produce polymer-modified cement mortars. The following polymers were tested: styrene-butadiene copolymer, vinyl acetate-vinyl versatate copolymer, vinyl acetate-vinyl versatates terpolymer, vinyl acetate-ethylene copolymer, vinyl acetate-vinyl propionate copolymer, vinyl acetate-dibutyl maleate copolymer and vinyl acetate homopolymer. Measurements of compressive strength, dynamic modulus of elasticity, water absorption and bond-strength to a concrete substrate were carried out on the polymer-modified mortars in comparison to a reference mixture without polymers. Infrared and XRD analytical techniques were used to investigate the alkaline hydrolysis of the polymers and cement hydration, respectively. The results indicate that polymers with higher resistance to hydrolysis performed better in terms of higher bond strength to the concrete substrate and lower water absorption of the corresponding mortars.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83891490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polybasic organic phosphate and lignosulphonate were combined in appropriate proportions to be a kind of high-range retarder-plasticizer (KM) for use in higher temperatures. Various retarders have been used in ordinary concrete and roller-compacted concrete (RCC) for testing under 45(C) degrees and 25% relative humidity. Rheology and time of setting for fresh concrete and mechanical properties of hardened concrete, allowance of exposure time of bond between two construction layers of RCC, etc. were investigated. Simulated testing for Three Gorges Project was also carried out by testing at the Development General Co. and the Testing Center of Gezhouba group.
{"title":"Use of High-Range Retarder-Plasticizer for Roller-Compacted Concrete of the Three Gorges Project in China","authors":"Liang Wenquan, L. Huizhen, H. Zhen, Li Yajie","doi":"10.14359/6215","DOIUrl":"https://doi.org/10.14359/6215","url":null,"abstract":"Polybasic organic phosphate and lignosulphonate were combined in appropriate proportions to be a kind of high-range retarder-plasticizer (KM) for use in higher temperatures. Various retarders have been used in ordinary concrete and roller-compacted concrete (RCC) for testing under 45(C) degrees and 25% relative humidity. Rheology and time of setting for fresh concrete and mechanical properties of hardened concrete, allowance of exposure time of bond between two construction layers of RCC, etc. were investigated. Simulated testing for Three Gorges Project was also carried out by testing at the Development General Co. and the Testing Center of Gezhouba group.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81112904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Acrylic polymer (AP) performs better than other superplasticizers based on sulfonate-naphthalene-formaldehyde (SNF), sulfonated-melamine formaldehyde (SMF) or modified lignosulfonate (MLS). It is better than the other superplasticizers in terms of higher initial slump, at equal water-cement ratio (w/c), and lower rate of slump loss. AP, however, is a little more expensive than SMF and much more expensive than either NSF or MLS. Therefore, blending of AP with the other polymers could reduce the cost. The purpose of the present work was to study the influence of binary blended admixture (AP on one hand, and SNF, MSF or MLS on the other one) on the performance of superplasticized concretes in terms of slump, slump loss, specific gravity, air content and compressive strength at equal w/c. The data presented in this paper indicates that there is no practical advantage in blending AP with NSF or MSF. Moreover the combination of AP with NSF seems to be unreliable because produces an erratic reduction in the workability of the concrete mixture when about 75% of AP is replaced by NSF. On the other hand, a combination of AP with MLS appears to perform as well as the pure acrylic polymer in terms of workability, slump loss, air content and strength development, provided that the replacement of AP by MLS is not higher than 25%. Therefore, these blended AP-MLS superplasticizers appear to be very interesting because they are cheaper than the pure acrylic polymer at approximately equal performance.
{"title":"\"Blending of Acrylic Superplasticizer with Napthalene, Melamine or Lignosulfoate-Based Polymers\"","authors":"L. Coppola, E. Erali, R. Troli, M. Collepardi","doi":"10.14359/6185","DOIUrl":"https://doi.org/10.14359/6185","url":null,"abstract":"Acrylic polymer (AP) performs better than other superplasticizers based on sulfonate-naphthalene-formaldehyde (SNF), sulfonated-melamine formaldehyde (SMF) or modified lignosulfonate (MLS). It is better than the other superplasticizers in terms of higher initial slump, at equal water-cement ratio (w/c), and lower rate of slump loss. AP, however, is a little more expensive than SMF and much more expensive than either NSF or MLS. Therefore, blending of AP with the other polymers could reduce the cost. The purpose of the present work was to study the influence of binary blended admixture (AP on one hand, and SNF, MSF or MLS on the other one) on the performance of superplasticized concretes in terms of slump, slump loss, specific gravity, air content and compressive strength at equal w/c. The data presented in this paper indicates that there is no practical advantage in blending AP with NSF or MSF. Moreover the combination of AP with NSF seems to be unreliable because produces an erratic reduction in the workability of the concrete mixture when about 75% of AP is replaced by NSF. On the other hand, a combination of AP with MLS appears to perform as well as the pure acrylic polymer in terms of workability, slump loss, air content and strength development, provided that the replacement of AP by MLS is not higher than 25%. Therefore, these blended AP-MLS superplasticizers appear to be very interesting because they are cheaper than the pure acrylic polymer at approximately equal performance.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84497316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The relationship among the amounts of adsorption admixtures to cement particles, the interactive force between cement particles and the zeta potential of cement particle and fluidity of cement paste prepared at the W/C ratio of 0.3 with lignin sulfonic acid-based admixture (LS), aminobenzene sulfonic acid-based admixture (AS) or melmine sulfonic acid-based admixture (MS) was studied in this paper, aiming at obtaining the basic data for elucidating the effects of the characters of sulfonic acid-based organic admixtures on the fluidity of concrete. The amount of adsorption of the sulfonic acid-based admixture by cement particles are logarithmically related to the molecular weight of the admixtures. The lower the molecular weight, the more the amount adsorbed are. The zeta potential of cement particle in cement paste depends upon the content of sulfonate group in the admixture and the adsorption state of admixture. The interactive force between cement particles are linearly related to the fluidity of cement paste. The steric repulsive force considerably contributes to the dispersion of particles even in the addition of sulfonic acid-based admixture which has been considered so far to disperse the particles mainly by the electrostatic repulsive factor. The steric repulsive force is related to the molecular weight of the sulfonic acid-based admixture except AS. The rate of contribution of electrostatic repulsive force to the total repulsive force accounting for the interactive force correlates with the content of sulfonate group in the admixture. The reason why the action of AS is different from those other mixtures is probably because the adsorption state of AS is different than those from others.
{"title":"Influence of Characteristics of Sulfonic Acid-Based Admixture on Interactive Force Between Cement Particles and Fluidity of Cement Paste","authors":"H. Uchikawa, S. Hanehara","doi":"10.14359/6176","DOIUrl":"https://doi.org/10.14359/6176","url":null,"abstract":"The relationship among the amounts of adsorption admixtures to cement particles, the interactive force between cement particles and the zeta potential of cement particle and fluidity of cement paste prepared at the W/C ratio of 0.3 with lignin sulfonic acid-based admixture (LS), aminobenzene sulfonic acid-based admixture (AS) or melmine sulfonic acid-based admixture (MS) was studied in this paper, aiming at obtaining the basic data for elucidating the effects of the characters of sulfonic acid-based organic admixtures on the fluidity of concrete. The amount of adsorption of the sulfonic acid-based admixture by cement particles are logarithmically related to the molecular weight of the admixtures. The lower the molecular weight, the more the amount adsorbed are. The zeta potential of cement particle in cement paste depends upon the content of sulfonate group in the admixture and the adsorption state of admixture. The interactive force between cement particles are linearly related to the fluidity of cement paste. The steric repulsive force considerably contributes to the dispersion of particles even in the addition of sulfonic acid-based admixture which has been considered so far to disperse the particles mainly by the electrostatic repulsive factor. The steric repulsive force is related to the molecular weight of the sulfonic acid-based admixture except AS. The rate of contribution of electrostatic repulsive force to the total repulsive force accounting for the interactive force correlates with the content of sulfonate group in the admixture. The reason why the action of AS is different from those other mixtures is probably because the adsorption state of AS is different than those from others.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81601368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effectiveness of CA(NO2)2 and NaNO2 as corrosion inhibitors has been confirmed. However, the behavior of NO2-ion and its stability in the pore solution in concrete containing the inhibitors is a matter of concern for their effective use as a corrosion-inhibiting admixture. Furthermore, it may be important from the viewpoint of the corrosion of reinforcement in concretes contaminated with CI-ion to examine the behavior of No2-ions in relation to CI-ion concentration in the pore solution in concrete. In this study, the analyses of pore solutions expressed from NaCI containing-mortars with and without the inhibitors were carried out to elucidate effects of the inhibitors on the chloride binding capacity of mortars. Simultaneously, the corrosion rate of steel bars embedded in the mortars was monitored by measurements of the potential and polarization resistance. The NO2-ion concentrations in the pore solutions in NaCI-containing mortars treated with 1% Ca(NO2)2 by mass of cement were lower than those in the corresponding mortars with NaNO2. The addition of NaNO2 raised the OH-ion concentration slightly, but the OH-ion concentration was somewhat reduced in the mortars with Ca(NO2)2. The combined addition of NaCI and NaNO2, on the other hand, greatly raised the OH-ion concentration. However, the CI- /NO2- ratios in the pore solutions in mortars containing Ca(N)2)2 were slightly lower than in mortars containing NaNO2 because of the dissipation of greater amounts of CI-ions from the pore solutions in the former than in the latter.
{"title":"Pore Solution Composition and Electrochemical Behavior of Steel Bars in Mortars with Nitrite Corrosion Inhibitors","authors":"M. Kawamura, S. Tanikawa, R. Swamy, H. Koto","doi":"10.14359/6177","DOIUrl":"https://doi.org/10.14359/6177","url":null,"abstract":"The effectiveness of CA(NO2)2 and NaNO2 as corrosion inhibitors has been confirmed. However, the behavior of NO2-ion and its stability in the pore solution in concrete containing the inhibitors is a matter of concern for their effective use as a corrosion-inhibiting admixture. Furthermore, it may be important from the viewpoint of the corrosion of reinforcement in concretes contaminated with CI-ion to examine the behavior of No2-ions in relation to CI-ion concentration in the pore solution in concrete. In this study, the analyses of pore solutions expressed from NaCI containing-mortars with and without the inhibitors were carried out to elucidate effects of the inhibitors on the chloride binding capacity of mortars. Simultaneously, the corrosion rate of steel bars embedded in the mortars was monitored by measurements of the potential and polarization resistance. The NO2-ion concentrations in the pore solutions in NaCI-containing mortars treated with 1% Ca(NO2)2 by mass of cement were lower than those in the corresponding mortars with NaNO2. The addition of NaNO2 raised the OH-ion concentration slightly, but the OH-ion concentration was somewhat reduced in the mortars with Ca(NO2)2. The combined addition of NaCI and NaNO2, on the other hand, greatly raised the OH-ion concentration. However, the CI- /NO2- ratios in the pore solutions in mortars containing Ca(N)2)2 were slightly lower than in mortars containing NaNO2 because of the dissipation of greater amounts of CI-ions from the pore solutions in the former than in the latter.","PeriodicalId":21898,"journal":{"name":"SP-173: Fifth CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1997-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78514942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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