| Composition design of the optimum bloating activation condition for artificial lightweight aggregate using coal ash |
Young Min Wie
, Ki Gang Lee
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| Department of Materials Engineering, Kyonggi University, Suwon 162‑27, Korea |
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Received: November 27, 2019; Revised: December 20, 2019 Accepted: February 18, 2020. Published online: February 29, 2020. |
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| ABSTRACT |
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This study analyzed the characteristics of reject ash and bottom ash as raw materials for lightweight aggregate and suggested an optimum mixing ratio for recycling coal ash. The physical and chemical properties of reject ash and bottom ash for the manufacture of lightweight aggregate were examined. Rapid sintering tests were conducted to find an optimum mixing ratio to produce lightweight aggregates, density was measured, and cross-sections were observed. XRD-CT analysis was performed to observe the crystal phase distribution of the lightweight aggregate. Aggregate was sintered in a pilot rotary kiln using the optimum mixing ratio obtained through the experiment and its properties were measured. Coal ash has been found to be an unsuitable raw material for producing lightweight aggregate. By adding 3 wt% of carbon and 5 wt% of Fe2O3 to the bottom ash-dredged soil mixture, it was possible to prevent the adhesion of aggregate at the bloating activation temperature by lowering the firing temperature. Aggregates manufactured in the pilot rotary kiln meet the relevant standards and exhibit properties similar to those of commercial aggregates. |
| Key words:
Bloating activation zone · Lightweight aggregate · Black core · Viscous behavior · XRD-CT |
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