There are many cracked concrete structures worldwide. Although there have been numerous efforts to eliminate cracks, some cracks are very harmful and should be repaired as soon as possible. On the other hand, some cra...There are many cracked concrete structures worldwide. Although there have been numerous efforts to eliminate cracks, some cracks are very harmful and should be repaired as soon as possible. On the other hand, some cracks are almost harmless. So, a good guideline regarding how to deal with cracks in concrete structures is needed. In this guideline, the practical investigation, repair and strengthening method of cracked concrete structures is discussed. And the detecting subjects are cracks generated immediately after casting and during the service time. This guideline targets on the owners (including managers) of concrete structure and the engineers working for the maintenance of concrete structure. JCI (Japan Concrete Institute) published first version of "Practical Guideline for Investigation and Repair of Cracked Concrete Structures" in 1980, and then the fourth version titled "Practical Guideline for Investigation, Repair and Strengthening of Cracked Concrete Structures--2009" was published. This guideline is very practical when cracks are observed in existing concrete structures, in any other countries as well as in Japan. These three authors led the establishment of this guideline.展开更多
The European Standard EN 1504 "Products and systems for protection and repair of concrete structures -- Definitions, requirements, quality control and evaluation of conformity" can be considered a real milestone for...The European Standard EN 1504 "Products and systems for protection and repair of concrete structures -- Definitions, requirements, quality control and evaluation of conformity" can be considered a real milestone for the companies involved in the rehabilitation of buildings, bridges, piers, pipelines, and other civil or industrial concrete structures. However in some cases the examination and, even more, the practical application of the proposed guidelines are made difficult by a complicated sub-division in principles and methods, and by a confusing and repetitive layout. The paper deals in particular with the principles and methods for the rehabilitation of concrete damage due to reinforcement corrosion, often strictly connected, anyway, to those adopted in order to rehabilitate the concrete itself. Suggestions are given for a possible future update of the Standard, based on the personal experience of the Authors.展开更多
As a result of longer term exploitation, exposure to severe weather conditions or influence of chemical conditions, concrete walls of concrete structures get damaged internally as well as externally. This study includ...As a result of longer term exploitation, exposure to severe weather conditions or influence of chemical conditions, concrete walls of concrete structures get damaged internally as well as externally. This study includes a preliminary analysis of chemically treated water in existing concrete structures, and another after the application of the method and using materials for the structures in future. One of the priorities was to examine the existing concrete structures by using nondestructive and destructive methods. After that, based on the results of the analysis, adequate new materials are proposed for the repairs, most commonly new technology polymer carbonated materials, in order to achieve durability of structure elements in using technological processes. Behavior of the repairing structures was tested using the in situ methods, and especially pull-of test, to verify the adhesion force between the old concrete structures and new applied layer. After the repairing, the concrete structures will be monitored to record the behavior under the chemical treated water.展开更多
This paper investigates the strength and deformation characteristics of reinforced normal and high-strength concrete rectangular beams which failed in shear and repaired by external bonding of carbon fiber and steel p...This paper investigates the strength and deformation characteristics of reinforced normal and high-strength concrete rectangular beams which failed in shear and repaired by external bonding of carbon fiber and steel plate. Five simply supported reinforced concrete beams with shear reinforcement are tested, three of which are made with NSC (normal-strength concrete) and the other two with HSC (high-strength concrete). The span of the simply supported beams is 0.9 m with 100 mm wide by 200 mm deep cross section. All five beams are tested under four-point bending. Careful repair process is adopted and proved successful. The aim is to restore or increase shear strength of these beams and to monitor their post-repair load-deflection behavior. The effect of concrete compressive strength on the behavior and strength of beams before and after repair is also investigated. Shear cracks patterns and their evolution are observed and discussed.展开更多
文摘There are many cracked concrete structures worldwide. Although there have been numerous efforts to eliminate cracks, some cracks are very harmful and should be repaired as soon as possible. On the other hand, some cracks are almost harmless. So, a good guideline regarding how to deal with cracks in concrete structures is needed. In this guideline, the practical investigation, repair and strengthening method of cracked concrete structures is discussed. And the detecting subjects are cracks generated immediately after casting and during the service time. This guideline targets on the owners (including managers) of concrete structure and the engineers working for the maintenance of concrete structure. JCI (Japan Concrete Institute) published first version of "Practical Guideline for Investigation and Repair of Cracked Concrete Structures" in 1980, and then the fourth version titled "Practical Guideline for Investigation, Repair and Strengthening of Cracked Concrete Structures--2009" was published. This guideline is very practical when cracks are observed in existing concrete structures, in any other countries as well as in Japan. These three authors led the establishment of this guideline.
文摘The European Standard EN 1504 "Products and systems for protection and repair of concrete structures -- Definitions, requirements, quality control and evaluation of conformity" can be considered a real milestone for the companies involved in the rehabilitation of buildings, bridges, piers, pipelines, and other civil or industrial concrete structures. However in some cases the examination and, even more, the practical application of the proposed guidelines are made difficult by a complicated sub-division in principles and methods, and by a confusing and repetitive layout. The paper deals in particular with the principles and methods for the rehabilitation of concrete damage due to reinforcement corrosion, often strictly connected, anyway, to those adopted in order to rehabilitate the concrete itself. Suggestions are given for a possible future update of the Standard, based on the personal experience of the Authors.
文摘As a result of longer term exploitation, exposure to severe weather conditions or influence of chemical conditions, concrete walls of concrete structures get damaged internally as well as externally. This study includes a preliminary analysis of chemically treated water in existing concrete structures, and another after the application of the method and using materials for the structures in future. One of the priorities was to examine the existing concrete structures by using nondestructive and destructive methods. After that, based on the results of the analysis, adequate new materials are proposed for the repairs, most commonly new technology polymer carbonated materials, in order to achieve durability of structure elements in using technological processes. Behavior of the repairing structures was tested using the in situ methods, and especially pull-of test, to verify the adhesion force between the old concrete structures and new applied layer. After the repairing, the concrete structures will be monitored to record the behavior under the chemical treated water.
文摘This paper investigates the strength and deformation characteristics of reinforced normal and high-strength concrete rectangular beams which failed in shear and repaired by external bonding of carbon fiber and steel plate. Five simply supported reinforced concrete beams with shear reinforcement are tested, three of which are made with NSC (normal-strength concrete) and the other two with HSC (high-strength concrete). The span of the simply supported beams is 0.9 m with 100 mm wide by 200 mm deep cross section. All five beams are tested under four-point bending. Careful repair process is adopted and proved successful. The aim is to restore or increase shear strength of these beams and to monitor their post-repair load-deflection behavior. The effect of concrete compressive strength on the behavior and strength of beams before and after repair is also investigated. Shear cracks patterns and their evolution are observed and discussed.