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No.13 (1977/03) >

Title :石垣島の鉄筋コンクリート造校舎の耐久性
Title alternative :An Investigation Studiy on Durability and Deterioration of Reinforced Concrete School Houses in Ishigaki Island
Authors :具志, 幸昌
和仁屋, 晴讙
伊良波, 繁雄
Authors alternative :Gushi, Yukimasa
Waniya, Haruyoshi
Iraha, Shigeo
Issue Date :28-Mar-1977
Abstract :This paper describes an study on durability aspect of reinforced concrete school houses in Ishigaki Island. The school houses have been seriouly damaged on account of corrosion of steel bars embeded in concrete. The highest salt content of concrete samples taken from school houses amounts to as high as 1.41%, and the average salt content of the samples is 0.37%. The salt contained in concrete has been responsible for the above damages. 33% of all of the school houses are damaged in columns and girders, and 83% of school houses are deteriorated in some to considerable degree in slabs. It must be said that some fundamental changes in the method of construction of reinforced concrete school buildings are needed. Some remarks clarified in this investigation are mentioned: 1. The salt above come from sea sands, sea gravels and mixing water. Some salt in concrete also come from sea water directly. The concrete made from sea gravels contains 0.52% of salt in mortar weight, and the concrete made from crushed stones contained 0.24% salt on the average. 2. The protective measures for harmful salt content must be taken by regulating not only the use of sea sands but also the use of sea gravels. The mixing water other than tap water must be examined before its use. 3. The average values of concrete samples in specific weight and absorption capacity are 2.23 and 9.49%, respectively. These values show the concrete quality of the school houses in this island are not durable. 4. Even the laves in newly built school houses are slightly damaged. The most responsible for this fact is poor construction practice in placing steel bars. 5. The hand-rails of stairs are damaged at 100% degree. The conditions exposed to rain, wind and sunshine, small cross sections and containing many steel bar in small spaces are responsible for the above damage. 6. The high ratio of damaged school houses are due partly to small number of newly built houses, which comes from decreasing tendency of population in Ishigaki Island. 7. Slabs near the outdoor columns and lave ends are damaged fastly and seriously. The main reasons for the above are their small dimensions and thin concrete covers on steel bars.
Type Local :紀要論文
ISSN :0387-429X
Publisher :琉球大学理工学部
URI :http://hdl.handle.net/20.500.12000/26814
Citation :琉球大学理工学部紀要. 工学篇 = Bulletin of Science & Engineering Division, University of the Ryukyus. Engineering no.13 p.147 -201
Appears in Collections:No.13 (1977/03)

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