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Kakegawa M.,Taiheiyo Materials Corporation | Masuda Y.,Utsunomiya University | Matsubayashi Y.,Taiheiyo Materials Corporation | Kage T.,Japan Building Research Institute
Journal of Structural and Construction Engineering | Year: 2012

This paper reports the results of long-term outdoor exposure test on the rate of corrosion of reinforcing bar in concrete which contains chloride ion. The factor of experiment are sodium chloride content (0∼1.0%sand), water-cement ratio (50∼65%), and thickness of concrete cover (15∼40mm).It is concluded as follows, The corrosion loss of reinforcing bar in long-term outdoor exposure test increases in proportion to square root of exposure period. Rate of corrosion of reinforcing bar decreases with increasing thickness of concrete cover in sodium chloride content( 0∼0.3%/sand). The estimation equation of the rate of corrosion of sodium chloride content(0∼1.0/sand) are proposed by thickness of concrete cover and water- cement ratio.


Kakegawa M.,Taiheiyo Materials Corporation | Masuda Y.,Utsunomiya University | Matsubayashi Y.,Taiheiyo Materials Corporation | Kage T.,Japan Building Research Institute
Journal of Structural and Construction Engineering | Year: 2012

This paper reports the results of accelerated test (20°C, 40°C, 60°C and 80°C , moist condition) on the rate of corrosion of reinforcing bar in concrete which contains chloride ion. The factor of experiment are sodium chloride content (0∼1.0%/sand), water-cement ratio (50∼65%), and thickness of concrete cover (10∼30mm). It is concluded as follows, The corrosion loss of reinforcing bar in accelerated test increases in proportion to square root of test period. Rate of corrosion of reinforcing bar in carbonated concrete containing sodium chloride is larger than the rate of corrosion of reinforcing bar in un-carbonated concrete containing sodium chloride. The estimation equation of the rate of corrosion of reinforcing bar in concrete are proposed by sodium chloride content and water- cement ratio.


Kakegawa M.,Taiheiyo Materials Corporation | Masuda Y.,Utsunomiya University | Matsubayashi Y.,Taiheiyo Materials Corporation | Kage T.,Japan Building Research Institute
Journal of Structural and Construction Engineering | Year: 2012

This paper reports the results of accelerated test (60°C and 80°C, moist condition) on the rate of corrosion of reinforcing bar in concrete which contains chloride ion. The factor of experiment are sodium chloride content (0∼1.0%/sand), water-cement ratio (50∼65%), and thickness of concrete cover (15∼40mm).It is concluded as follows, The corrosion loss of reinforcing bar in accelerated test increases in proportion to square root of exposure period. Rate of corrosion of reinforcing bar in concrete containing 0 and 0.1% sodium chloride in 80°C is larger than rate of corrosion in 60°C. However rate of corrosion of reinforcing bar in concrete containing 0.3 and 1.0% sodium chloride in 80°C is smaller than rate of corrosion in 60°C. The estimation equation of the rate of corrosion of sodium chloride content(0∼1.0%/sand) are proposed by thickness of concrete cover and water- cement ratio.


Tanibe T.,Taiheiyo Materials Corporation | Ozawa M.,Gunma University | Kamata R.,Taiheiyo Materials Corporation | Rokugo K.,Gifu University
Journal of Structural Fire Engineering | Year: 2014

This paper reports on an experimental study regarding the behavior of restrained high-strength concrete in response to the type of extreme heating associated with fire. The study was intended to support estimation of thermal stress from the strain in a restraining steel ring and vapor pressure in restrained concrete under the conditions of a RABT 30 rapid heating curve. The size of the specimens was φ300 × 100 mm, and the results showed that explosive spalling occurred between 4 and 10 minutes in terms of heating time. It was also observed that the thermal stress was greater than the vapor pressure value of 0.1 MPa at a point 10 mm from the heated surface at 5 minutes. The maximum spalling depth was about 61 mm. It was inferred that spalling behavior caused by thermal stress may become predominant under restrained conditions. © 2014 Journal of Structural Fire Engineering. All Rights Reserved.


Nishimura S.,Utsunomiya University | Masuda Y.,Utsunomiya University | Kage T.,Japan Building Research Institute | Matsubayashi Y.,Taiheiyo Materials Corporation
Journal of Structural and Construction Engineering | Year: 2010

This paper reports the results of outdoor exposure test on the repair performance on corrosion of reinforcing bar in saIt containing concrete by various repairing materials. When there is much chlorination amount ofmaterial in the concrete, effect on repression of the reinforcing bars corrosion by the repair method of construction can't be expected very much. When the repair of the section repair part is done, that countermeasure is important frorn showing a tendency of progressing in the part of the boundary remarkably as for the reinforcing bars corrosion after the repair. If chipping isn't taken to the back of the reinforcing bars, the effect of rust is prevented material, section repair material, When chlorination amo?it ofmaterial increases, corrosion spreads out in surface direction and depth direction as well.


Tanibe T.,Taiheiyo Materials Corporation | Ozawa M.,Gunma University | Kamata R.,Taiheiyo Materials Corporation | Sato R.,Gifu University | Rokugo K.,Gifu University
MATEC Web of Conferences | Year: 2013

This paper reports on an experimental study regarding the behavior of steel ring-restrained concrete in response to fire exposure. The study was conducted to enable estimation of thermal stress based on steel ring strain in such concrete under the conditions of a RABT 30 heating curve. The specimens used were made from high-strength concrete (Fc: 80 MPa) restrained using steel rings with thicknesses of 0.5, 8 and 18 mm. © Owned by the authors, published by EDP Sciences, 2013.


Nagashio Y.,Taiheiyo Materials Corporation | Masuda Y.,Utsunomiya University
Journal of Structural and Construction Engineering | Year: 2010

This study discusses the drying shrinkage and the carbonation of Ecocement with ground granulated blast-furnace slag, as compared with those of Ordinary portland cement with ground granulated blast-furnace slag. As a result, The drying shrinkage of Ecocement with ground granulated blast-furnace slag had become small, as compared with that of Ordinary portland cement with ground granulated blast-furnace slag, in case of ground granulated blast-furnace slag 50% mixture. The carbonation of Ecocement and Ordinary portland cement with ground granulated blast-furnace slag was increase, but the increase ratio of carbonation when ground granulated blast-furnace slag was mixed was different in Ecocement and the Ordinary portland cement.


Lin W.,Waseda University | Yoda T.,Waseda University | Taniguchi N.,Maebashi Institute of Technology | Satake S.,Taiheiyo Materials Corporation | Sugino Y.,Taiheiyo Materials Corporation
Life-Cycle of Structural Systems: Design, Assessment, Maintenance and Management - Proceedings of the 4th International Symposium on Life-Cycle Civil Engineering, IALCCE 2014 | Year: 2015

A strengthening method for old steel railway bridges by using rubber-latex mortar, GFRP plates, lightweight rapid hardening concrete, and reinforcing bars was introduced in this paper. The present method was used to strengthen an old steel railway bridge that has been used for 61 years, and field tests were performed on both strengthened and un-strengthened bridges to confirm the real effects of this strengthening method. Both experimental and numerical results indicate that the present renovation method can greatly enhance the stiffness and reduce the stress levels of steel members, resulting in the extension of the residual service life of the old steel railway bridge. © 2015 Taylor & Francis Group, London.


Lin W.,Waseda University | Yoda T.,Waseda University | Taniguchi N.,Maebashi Institute of Technology | Satake S.,Taiheiyo Materials Corporation | Kasano H.,Waseda University
Journal of Constructional Steel Research | Year: 2014

Structural repairing or maintenance technique has been a hot issue in recent years due to the increasing aging problems of old railway bridges. A strengthening method for welded joints in old steel railway bridges by integrating the rapid hardening concrete, rubber-latex mortar, and reinforcing bars is introduced in this paper. The purpose of the present study is to investigate the mechanical performance of the strengthened connection joints in old steel railway bridges. Depending on the locations of the concrete and possible loading conditions, the joint needs to sustain both negative and positive bending moment, therefore, two experimental plans were employed. The static loading tests on the steel joints before and after strengthening were performed to confirm the effects of the present strengthening method. Moreover, three-dimensional FE models were built to make a comparison study between the strengthened and original steel joints. Load versus deflection relationship and strain development process on the web of the joints were measured and compared between the original joints and the strengthened joints. Both experimental and numerical results indicate that the present strengthening method can greatly enhance the stiffness and reduce the stress levels of steel joints, resulting in the extension service life of aged steel railway bridges. © 2013 Elsevier Ltd.

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