報告書番号

382047

タイトル（和文）

膨脹コンクリートの圧縮クリープ特性

タイトル（英文）

CREEP CHARACTERISTICS OF EXPANSIVE CONCRETE UNDER UNIAXIAL COMPRESSIVE STRESSES

概要 （図表や脚注は「報告書全文」に掲載しております）

地中線シールドトンネル二次覆工コンクリートのひびわれ発生を防止するために，その対策の一環として，膨脹コンクリートを試験施工区間に打設して現地計測を実施した。本報告は，この現地計測した二次覆工コンクリートの応力解析に必要となる膨脹コンクリートの圧縮クリープ特性についてまとめたものである。膨脹コンクリートの圧縮クリープに及ぼす載荷材令，温度および養生条件の影響について検討を加えるとともに，引張クリープとの比較を行った。その結果膨脹材を多量に使用し，膨脹効果を期待するコンクリートは通常のコンクリートに較べ特に若材令載荷の場合に，クリープが特異な性状を示すことを明らかにした。これは膨脹コンクリートの適用に際し，留意すべき事項であることを指摘した。また，応力解析に直接使用できるように，クリープ曲線の関数表示式を与えた。

概要 （英文）

THIS PAPER DISCUSSED EXPERIMENTAL RESULTS OFTHE CREEP CHARACTERISTICS OF EXPANSIVE CONCRETE SUBJECTED TO UNIAXIAL COMPRESSIVE STRESSES FOR THE PURPOSE OF APPLYING THE CREEP ANALYSIS OF LINING CONCRETE FOR SHIELD TUNNEL. A SUMMARY OF THE RESULTS IS AS FOLLOWS. (1)EFFECT OF LOADING AGE ON COMPRESSIVE CREEP; 1)THE YOUNGER THE LOADING AGE OF EXPANSIVE AND NON-EXPANSIVE CONCRETE,THE LARGER THE CREEP UNDER UNIAXIAL COMPRESSION BECAME. 2)THE CREEP OF CONCRETE WHICH IS MIXED WITH THE EXPANSIVE ADMIXTURE HAVING LOW HYDRATION HEAT(UNIT CONTENT;30KG/CUBIC M),WAS NEARLY EQUIVALENT TO THAT OF ORDINARY NONEXPANSIVE CONCRETE. 3)THE CREEP OF EXPANSIVE CONCRETE(UNIT CONTENT:55KG/CUBIC M),WHICH WAS LOADED AT THE AGE OF 3 DAYS AFTER MIXING,WAS CONSIDERABLY LARGER OWING TO THE INCREASED PERCENTAGE OF ETTRINGITE PRODUCED IN THE HYDRATION PHASE. 4)THE CREEP LOADED AT THE AGE OF 7 DAYS WAS NEARLY 1.5 TIMES AS LARGE AS THAT AT 28DAYS,AND WAS INDEPENDENT OF MIX PROPORTIONS. (2)IN CASE OF OLD AGED CONCRETE,IT IS WELL KNOWN THAT THE HIGHER THE TEMPERATURE OF CONCRETE,THE LARGER THE CREEP OF CONCRETE BECAME.HOWEVER,THECOMPRESSIVE CREEP OF YOUNG EXPANSIVE CONCRETE,SEALED IN COPPER JACKETS,STORED FROM THE AGE OF 5DAYS AT 40 DEGREE AND LOADED AT THE AGE OF 7 DAYS,WAS APPROXIMATELY EQUAL TO THAT AT 20 DEGREE DUE TO THE EFFECT OF THERMALLY ACCELERATED HYDRATION,I.E.,AGEING. (3)THE CREEPS OF EXPANSIVE CONCRETES STORED IN SEALED AND UNDER WATER CONDITIONS WERE IDENTICAL ATTHE AGE OF 6 MONTHS AFTER LOADING.ON THE OTHER HAND,THE CREEP OF CONCRETE SUBJECTED TO SIMULATANEOUS DRYING WAS REMARKABLY INCREASED,NAMEY THE CREEP AFTER 6 MONTHS WAS 1.75 TIMES AND 1.92 TIMES AS LARGE AS THAT OF SEALED AND IN-WATERED CONCRETES,RESPECTIVELY. (4)A LOGARITHMIC SPECIFE CREEP FUNCTION COMBINED WITH A HYPERBOLA,GAVE A MOST APPROPRIATE FITTING TO THE EXPERIMENTAL DATA.

報告者

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