Concrete Research and Technology
Online ISSN : 2186-2745
Print ISSN : 1340-4733
ISSN-L : 1340-4733
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Volume 21, Issue 1
Displaying 1-6 of 6 articles from this issue
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  • Proposal for Estimation Method of Surface Chloride Content of RC Deck in Open-Piled Pier considering the Structural Types and the Influence of Wave Action
    Takahiko Amino, Nobuaki Otsuki, Tsuyoshi Saito, Takashi Habuchi
    2010 Volume 21 Issue 1 Pages 1_1-1_11
    Published: 2010
    Released on J-STAGE: December 22, 2011
    DOIhttps://doi.org/10.3151/crt.21.1_1
    JOURNAL FREE ACCESS
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    In this paper, the surface chloride content at the different positions in over 15-years old RC decks in open-piled piers with the various structural types and wave action were analyzed. The structural types were classified in terms of the existence or nonexistence of the curtain wall at the berthing side and the revetment behind the pier. Also, as the wave action, the wave from the open sea and the position of ship's arrival were considered. As the results, the value of surface chloride content was varied depending on the distance from the sea level. Furthermore, the value was influenced by the difference in structural types of RC decks and the wave action. From these results, the relation between the surface chloride content and the distance from the sea level, which can apply to the positions that not influenced by the structural types and the wave action, has been proposed. Moreover, the surface chloride content at the positions that influenced by the structural types and the wave action could be estimated by adding the proper amount of correction to the value calculated by the above proposed relation.
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  • Fundamental Study on Mechanical Performance of Rigid Joint PCaPC Member to Cast-in-place Bottom Slab
    Masahiro Nakai, Nobuaki Arai, Hidenori Hamada
    2010 Volume 21 Issue 1 Pages 1_13-1_24
    Published: 2010
    Released on J-STAGE: December 22, 2011
    DOIhttps://doi.org/10.3151/crt.21.1_13
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    This paper describes reports the mechanical performance of the new rigid joint system of PCaPC member and cast-in-place bottom slab .This rigid joint is PRC structure which is to connect the PC bar and reinforcement to the special metal anchor plate embedded in the PCaPC member and to introduce tensioning force to the joint face, and this rigid joint has the restoration performance. The static loading test using the full scale model shows as follows: 1) this rigid joint is able to be designed using the same method as the joint-less structure and has seismic performance and anti water leak performance same as the joint-less structure, 2) this metal anchoring system is designed by our original design concepts with structural appropriateness for Level 1 earthquake ground motion and the ultimate load.
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  • Development of a Simple Test Method to Assess Freeze-thaw Resistance of Recycled Aggregate
    Hiroshi Katahira, Hiroshi Watanabe
    2010 Volume 21 Issue 1 Pages 1_25-1_33
    Published: 2010
    Released on J-STAGE: December 22, 2011
    DOIhttps://doi.org/10.3151/crt.21.1_25
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    This paper describes test method of freeze-thaw resistance on recycled aggregate. Proposed test method measures a variation of fineness modulus(F.M.) of recycled aggregate after 10 cycles of freeze-thaw with a freezer and a water bath. The F.M. variation of the test results showed good correlation to the durability factor of concrete using coarse recycled aggregates. We proposed a requirement for recycled aggregates to ensure required durability based on the test results.
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  • Properties of Ecocement Concrete Exposed in Marine Environment for Five Years
    Yasuhiro Nagashio, Masami Uzawa, Toru Yamaji, Yoshikazu Akira
    2010 Volume 21 Issue 1 Pages 1_35-1_48
    Published: 2010
    Released on J-STAGE: December 22, 2011
    DOIhttps://doi.org/10.3151/crt.21.1_35
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    This study discusses compressive strength, penetration of chloride ion and pore size distribution of Ecocemet concrete exposed in marine environments for five years. As a results, Compressive strength is not recognized to lower after exposed for five years. Penetration of chloride ion was admitted to permeate into Ecocement concrete. Total pore volume was admitted to decrease passing in the age , but the pore volume influencing the penetration of chloride ion was a lot of volumes. Ecocement concrete with blast-furnace slag powder was recognized the long-term strength gain, and Penetration of chloride ion did not permeate into Ecocement concrete with blast-furnace slag powder.
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  • A Study on Alkali-Silica Reactivity of Super Lightweight Aggregate Made of Yellow River Sedimentary Soil
    Masashi Funahashi, Koji Tsuruta, Takahiko Sasaki, Junichiro Niwa
    2010 Volume 21 Issue 1 Pages 1_49-1_61
    Published: 2010
    Released on J-STAGE: December 22, 2011
    DOIhttps://doi.org/10.3151/crt.21.1_49
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    It was found that there was a difference of reactivity between the surface portion and inside portion of super lightweight aggregates (SLA) made of the Yellow River sedimentary soil in the alkali-silica reaction (ASR) test. Moreover, neither harmful expansion was observed as a result of ASR test by Danish method with the concrete specimen using available lightweight aggregates (LA) and SLA. However, the formation of the ASR gel was not observed in SLA while the formation of the ASR gel was observed in the interface of mortar and the aggregate in LA. It was concluded that the alkali silica reactivity of SLA was very low. Therefore, SLA is available enough to actual concrete structures.
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  • Influence of Scaling Resistance on Frost Damage of Porous Concrete
    Takuro Nakamura, Takashi Horiguchi, Kazunori Shimura, Tuyoshi Ishii
    2010 Volume 21 Issue 1 Pages 1_63-1_72
    Published: 2010
    Released on J-STAGE: December 22, 2011
    DOIhttps://doi.org/10.3151/crt.21.1_63
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    Frost resistance of porous concrete (PoC) was examined based on the scaling and water absorption property under freeze-thaw action with JIS A 1148 procedure A/B and RILEM CIF/CDF tests. As a result, water absorption behavior of PoC could be subdivided into two parts: water absorption under isothermal temperature and frost suction during freezing and thawing cycles. Little amount of frost suction made PoC more resistant to frost scaling. Air entraining was effective against frost scaling of PoC, as well as that of conventional concrete. In addition, frost damage of PoC which has a service period of 10 years at cold climate corresponded to that of the replicated PoC. This replicated PoC had been subjected to approximately 40 freezing and thawing cycles with CDF test. In this study it was found that if the scaling quantity of PoC exceeds 300g/m2, the relative dynamic modulus of elasticity and the flexural strength sharply decreases. It was confirmed that the scaling resistance was an important factor to evaluate the frost resistance of PoC.
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