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Title |
Prediction of Setting Time of Concrete Using Fly Ash and Super Retarding Agent
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Keywords |
super retarding agent(SRA) ; fly ash ; maturity ; setting time ; equivalent age |
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Abstract |
This paper presents a method to estimate the setting time of concrete using super retarding agent(SRA) and fly ash(FA) under various curing temperature conditions by applying maturity based on equivalent age. To estimate setting time, the equivalent age using apparent activation energy(Ea) was applied. Increasing SRA content and decreasing curing temperature differences in response to mixture type. It is estimated to be from 24~35KJ/mol in all mixtures, which is smaller than that of conventional mixture ranging from 30~50KJ/mol. Based on the application of Ea to Freisleben-Hansen and Pederson's equivalent age function, equivalent age is nearly constant, regardless of curing temperature and SRA contents. This implies that the concept of maturity is applicable in estimating the setting time of concrete containing SRA. A high correlation between estimated setting time and measured setting time is observed. Multi-regression model to determine appropriate dosage of SRA reflection FA contents and equivalent age was provided. Thus, the setting time estimation method studied herein can be applicable to the concrete containing SRA and FA in construction fields.
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