P. Zhang, F. Wittmann, M. Haist, H. Müller, P. Vontobel, T. Zhao
{"title":"Water Penetration into Micro-cracks in Reinforced Concrete","authors":"P. Zhang, F. Wittmann, M. Haist, H. Müller, P. Vontobel, T. Zhao","doi":"10.1515/rbm14.20.2-0008","DOIUrl":"https://doi.org/10.1515/rbm14.20.2-0008","url":null,"abstract":"","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"47 1","pages":"85 - 94"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91159181","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}
{"title":"Composition and Properties of SHCC; Part I: Influence of Composition of Cement-based Matrix on Strain Capacity and Crack Distribution","authors":"R. Wu, P. Wang, F. Wittmann, T. Zhao","doi":"10.1515/rbm14.20.2-0010","DOIUrl":"https://doi.org/10.1515/rbm14.20.2-0010","url":null,"abstract":"","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"11 3 1","pages":"103 - 110"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88795500","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}
W. P. Lu, F. Wittmann, P. Wang, Y. Zaytsev, T. Zhao
{"title":"Influence of an Applied Compressive Load on Capillary Absorption of Concrete: Observation of Anisotropy","authors":"W. P. Lu, F. Wittmann, P. Wang, Y. Zaytsev, T. Zhao","doi":"10.1515/rbm14.20.2-0014","DOIUrl":"https://doi.org/10.1515/rbm14.20.2-0014","url":null,"abstract":"","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"26 1","pages":"131 - 136"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87863897","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}
{"title":"Influence of Moisture Content on Chloride Diffusion in Concrete","authors":"M. Zhang, P. Wang, F. Wittmann","doi":"10.1515/rbm14.20.2-0013","DOIUrl":"https://doi.org/10.1515/rbm14.20.2-0013","url":null,"abstract":"","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"43 1","pages":"127 - 130"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74863783","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}
P. Wang, F. Wittmann, P. Zhang, E. Lehmann, T. Zhao
{"title":"Observation of Water Penetration into Cracked and Water Repellent SHCC after Imposed Strain by Means of Neutron Radiography","authors":"P. Wang, F. Wittmann, P. Zhang, E. Lehmann, T. Zhao","doi":"10.1515/rbm14.20.2-0009","DOIUrl":"https://doi.org/10.1515/rbm14.20.2-0009","url":null,"abstract":"","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"189 1","pages":"95 - 102"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79463802","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}
Pub Date : 2014-04-01DOI: 10.12900/rbm14.20.2-0013
M. Zhang, P. Wang, F. Wittmann
Chloride penetration into the cover of reinforced concrete is often at the origin of early damage due to corrosion of the steel reinforcement. The penetration rate of chloride, however, depends strongly of the water content. If diffusion coefficients as measured on saturated concrete are used for the prediction of service life by means of Fick's second law, chloride penetration may be overestimated. The mobility of chloride in concrete in hygral equilibrium with different relative humidity of the surrounding air was determined experimentally. Chloride mobility in concrete, which is in equilibrium with 50 % RH, is very low. This has to be taken into consideration in realistic service life prediction. (A)
{"title":"Influence of Moisture Content on Chloride Diffusion in Concrete","authors":"M. Zhang, P. Wang, F. Wittmann","doi":"10.12900/rbm14.20.2-0013","DOIUrl":"https://doi.org/10.12900/rbm14.20.2-0013","url":null,"abstract":"Chloride penetration into the cover of reinforced concrete is often at the origin of early damage due to corrosion of the steel reinforcement. The penetration rate of chloride, however, depends strongly of the water content. If diffusion coefficients as measured on saturated concrete are used for the prediction of service life by means of Fick's second law, chloride penetration may be overestimated. The mobility of chloride in concrete in hygral equilibrium with different relative humidity of the surrounding air was determined experimentally. Chloride mobility in concrete, which is in equilibrium with 50 % RH, is very low. This has to be taken into consideration in realistic service life prediction. (A)","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"1 1","pages":"127 - 130"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83121057","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}
Pub Date : 2014-04-01DOI: 10.12900/rbm14.20.2-0007
P. Zhang, F. Wittmann, T. Zhao, E. Lehmann
By impregnation of concrete with a water repellent compound such as silane, a water repellent surface layer can be established. Due to this surface impregnation capillary absorption of water and aqueous salt solutions can be significantly reduced. The aim of this protective surface treatment is in many cases to obtain better frost resistance and to reduce chloride penetration. Water vapor can still transgress the impregnated layer in and out of concrete. In the contribution experimental results to visualize the width and the water content within the water repellent surface layer are described. The water distribution was determined quantitatively by neutron radiography. The results obtained allow to explain earlier findings, which indicated that an efficient chloride barrier can be established by deep impregnation only. In a water repellent layer with a thickness lower than 6 mm there remains enough water which allows reduced migration of chloride into the pore space of the material. The requirements of published recommendations are herewith supported and justified. (A)
{"title":"Investigations into the Water Repellent Surface Near Layer in Concrete by Neutron Radiography","authors":"P. Zhang, F. Wittmann, T. Zhao, E. Lehmann","doi":"10.12900/rbm14.20.2-0007","DOIUrl":"https://doi.org/10.12900/rbm14.20.2-0007","url":null,"abstract":"By impregnation of concrete with a water repellent compound such as silane, a water repellent surface layer can be established. Due to this surface impregnation capillary absorption of water and aqueous salt solutions can be significantly reduced. The aim of this protective surface treatment is in many cases to obtain better frost resistance and to reduce chloride penetration. Water vapor can still transgress the impregnated layer in and out of concrete. In the contribution experimental results to visualize the width and the water content within the water repellent surface layer are described. The water distribution was determined quantitatively by neutron radiography. The results obtained allow to explain earlier findings, which indicated that an efficient chloride barrier can be established by deep impregnation only. In a water repellent layer with a thickness lower than 6 mm there remains enough water which allows reduced migration of chloride into the pore space of the material. The requirements of published recommendations are herewith supported and justified. (A)","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"118 1","pages":"79 - 84"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86606746","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}
Pub Date : 2014-04-01DOI: 10.12900/rbm14.20.2-0009
P. Wang, F. Wittmann, P. Zhang, E. Lehmann, T. Zhao
Huge strain capacity of SHCC under tensile stress can be reached by multiple crack formation, while the cracks remain bridged by fibers. Under protective conditions the full strain capacity can be used in practice. In this contribution it is shown that even at comparatively modest imposed strain cracks are formed, which may transport water and ions dissolved in water deep into structural elements made of SHCC. One way to reduce water penetration into cracked SHCC has been investigated, the use of an integral water repellent cement-based matrix. It is shown that in this way water penetration is significantly reduced and hence durability is increased.
{"title":"Observation of Water Penetration into Cracked and Water Repellent SHCC after Imposed Strain by Means of Neutron Radiography","authors":"P. Wang, F. Wittmann, P. Zhang, E. Lehmann, T. Zhao","doi":"10.12900/rbm14.20.2-0009","DOIUrl":"https://doi.org/10.12900/rbm14.20.2-0009","url":null,"abstract":"Huge strain capacity of SHCC under tensile stress can be reached by multiple crack formation, while the cracks remain bridged by fibers. Under protective conditions the full strain capacity can be used in practice. In this contribution it is shown that even at comparatively modest imposed strain cracks are formed, which may transport water and ions dissolved in water deep into structural elements made of SHCC. One way to reduce water penetration into cracked SHCC has been investigated, the use of an integral water repellent cement-based matrix. It is shown that in this way water penetration is significantly reduced and hence durability is increased.","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"17 1","pages":"102 - 95"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86869353","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}
Migration of dissolved ions into concrete by capillary absorption (convection) and by diffusion has been studied in great detail in recent years. These two processes are considered to be major mechanisms of chloride penetration into concrete in contact with seawater or with water containing deicing salt. In practice, however, there exist many reinforced concrete structures, such as harbor constructions, subsea tunnels or bridge pillars, which are in permanent or temporary contact with salt containing water under considerable hydrostatic pressure. Penetration of chloride into concrete under hydrostatic pressure has been investigated to the same extent so far. Chloride penetration into concrete under the influence of a hydrostatic pressure has been studied on five types of concrete. The influence of blended cements has been investigated in particular. The results indicate that a pressure less than 0.1 MPa has hardly any influence on chloride penetration. Once the water pressure overcomes 0.3 MPa, the water and chloride penetration depth as well as the chloride content at a given exposure time increase significantly. If fly ash and slag are added to Portland cement, the resistance with respect to water and chloride penetration increases. Longer moist curing reduces the rate of chloride penetration. If an aqueous salt solution penetrates into concrete under hydrostatic pressure, the dissolved chloride does not follow the penetrating water but it is accumulated in a surface near zone. The porous structure of concrete obviously acts like a molecular filter. The ratio between water and chloride penetration depths can be expressed by means of an exponential function. (A)
{"title":"Penetration of Water and Chloride Dissolved in Water into Concrete under Hydraulic Pressure","authors":"Y. Zhao, F. Wittmann, P. Zhang, P. Wang, T. Zhao","doi":"10.1515/RBM14.20.2-0012","DOIUrl":"https://doi.org/10.1515/RBM14.20.2-0012","url":null,"abstract":"Migration of dissolved ions into concrete by capillary absorption (convection) and by diffusion has been studied in great detail in recent years. These two processes are considered to be major mechanisms of chloride penetration into concrete in contact with seawater or with water containing deicing salt. In practice, however, there exist many reinforced concrete structures, such as harbor constructions, subsea tunnels or bridge pillars, which are in permanent or temporary contact with salt containing water under considerable hydrostatic pressure. Penetration of chloride into concrete under hydrostatic pressure has been investigated to the same extent so far. Chloride penetration into concrete under the influence of a hydrostatic pressure has been studied on five types of concrete. The influence of blended cements has been investigated in particular. The results indicate that a pressure less than 0.1 MPa has hardly any influence on chloride penetration. Once the water pressure overcomes 0.3 MPa, the water and chloride penetration depth as well as the chloride content at a given exposure time increase significantly. If fly ash and slag are added to Portland cement, the resistance with respect to water and chloride penetration increases. Longer moist curing reduces the rate of chloride penetration. If an aqueous salt solution penetrates into concrete under hydrostatic pressure, the dissolved chloride does not follow the penetrating water but it is accumulated in a surface near zone. The porous structure of concrete obviously acts like a molecular filter. The ratio between water and chloride penetration depths can be expressed by means of an exponential function. (A)","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"29 1","pages":"117 - 126"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82482777","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}
{"title":"Investigations into the Water Repellent Surface Near Layer in Concrete by Neutron Radiography","authors":"P. Zhang, F. Wittmann, T. Zhao, E. Lehmann","doi":"10.1515/rbm14.20.2-0007","DOIUrl":"https://doi.org/10.1515/rbm14.20.2-0007","url":null,"abstract":"","PeriodicalId":20957,"journal":{"name":"Restoration of Buildings and Monuments","volume":"5 1","pages":"79 - 84"},"PeriodicalIF":0.0,"publicationDate":"2014-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78658818","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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