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Title |
Preventive Measures on Alkali -Silica Reaction of Crushed Stones
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Authors |
전쌍순 ; 이효민 ; 서기영 ; 황진연 ; 진치섭 |
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Keywords |
쇄석 골재; 알칼리-실리카 반응; 플라이애쉬; 실리카퓸; 메타카올린; crushed stone; alkali-silica reaction; fly ash; silica fume; metakaolin |
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Abstract |
In Korea, due to the insufficiency of natural aggregates and increasing needs of crushed stones, it is necessary to examine the alkali-silica reaction of the crushed stones. The reaction produces an alkali-silica reaction gel which can imbibe pore solution and swell to generate cracks that are visible In affected concrete. In general, crushed stones are tested by petrograptuc examination, chemical method and mortar-bar method, but the most reliable method Is mortar-bar test. This study tested alkali-silica reactivity of crushed stones of various rock types using ASTM C 227 and C 1260, and compared the results of two test methods. This study also analyzed effects of particle size and grading of reactive aggregate on alkali-silica reaction expansion of mortar-bar. The effectiveness of mineral admixtures to reduce detrimental expansion caused by alkali-silica reaction was investigated through the ASTM C 1260 method. The mineral admixtures used were nv ash, silica fume, metakaolin and ground granulated blast furnace slag. The replacement ratios of 0, 5, 10, 15, 25 and 35% were commonly applied for all the mineral admixtures and the replacement ratios of 45 and 55% were additional applied for the admixtures that could maintain workability. The results indicate that replacement ratios of 25% for ay ash, 10% for silica fume, 25% for metakaolin or 35% for ground granulated blast furnace slag were most effective to reduce alkali-silica reaction expansion under the experimental conditions.
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