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Title |
Effect of Fly Ash on Rheology and Strength of Recycled Aggregate Concrete
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DOI |
https://doi.org/10.4334/JKCI.2013.25.2.241 |
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Keywords |
순환골재 ; 플라이애쉬 ; 유동성 ; 압축강도 ; 쪼갬인장강도 recycled aggregate ; fly ash ; rheology ; compressive strength ; split tensile strength |
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Abstract |
As the amount of construction wastes increase, reuse of demolished concrete is being considered in research areas. Reflecting these interests, this experiment was performed to clarify concrete’s mechanical property and workability using recycled aggregate as a coarse aggregate. Eleven cases of concrete specimens were produced by changing the rates of replacement of coarse recycled aggregate, replacement of fly ash, design strength, and moisture state of coarse aggregate. Compressive and tensile split strength tests were taken to study the mechanical properties of hardened concrete. To verify flowability of fresh concrete, a slump test and a flow curve test using ICAR Rheometer were performed. It was found that using recycled aggregate and fly ash leads good workability by testing slump and flow curve. The yield stress of fresh concrete decreased with increase of recycled aggregate substitution rate. Through the test, it was confirmed that there is inversely proportional relationship between the slump and yield stress roughly. Recycled aggregate concrete containing fly ash has considerably lower plasticity viscosity than not containing fly ash. Strength test results showed that recycled aggregate tended to decrease compressive and tensile strength of concrete, when recycled aggregate was used as a coarse aggregate. Using over 30% recycled aggregate caused significant decreases in compressive and tensile strength. Replacing 30% cement with fly ash was helpful to improve the long-term strength of concrete.
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