Durability challenge of concrete due to Alkali Silica Reaction (ASR) was recognized during 1940 by Stanton. For design of concrete structures having life of 50 to 100 years such as bridges, dams, it is essential to carry out test on aggregates for knowing potential reactivity. ASR in concrete is caused due to sufficient quantity of reactive aggregates, alkalis from cement and moisture. Poorly crystalized silica such as amorphous or cryptocrystalline quartz in aggregates are potential reactive. ASR in concrete structure may appear after one or two decades and may accelerate deterioration in concrete due to other processes such as chloride or sulphate attacks. Various test methods exist for ASR based on standards such as ASTM, RILEM. Exclusive of any test method is not suitable for identifying potential ASR. Hence more than two or more tests are practiced. Minerals which contribute to potential reactivity recommended method is Petrographic Examination ASTM C 295 or RILEM AAR 1 is method to find minerals which contribute to potential reactivity. Bar Mortar Method is well accepted and ASTM 1260 C or RILEM AAR 2 is suitable to identify potential reactivity of aggregates. Use of Information Technology for advanced testing techniques needs to be established for identifying potential ASR in the field with laboratory testing.
کلید واژگان :ACR, ASR, TESTIng
ارزش ریالی : 300000 ریال
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