| Characteristics of artificial aggregates employing self-hydraulic fly ash |
| Woong-Geol Lee1, Myong-Shin Song2, Kyung-Nam Kim1 |
1Department of Advanced Materials Engineering, Kangwon National University, Samcheok 245-711, Republic of Korea
2Research Center of Advanced Convergence Processing on Materials, Kangwon National University, Samcheok 245-711, Republic of Korea |
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Received: November 13, 2020; Revised: July 31, 2021 Accepted: August 3, 2021. Published online: September 30, 2021. |
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| ABSTRACT |
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Due to the instability of the aggregate supply and demand chain, it is expected that the price of aggregate will increase, consequently increasing construction expenses. Therefore, achieving a stable aggregate supply and demand chain by developing alternative aggregates and implementing environmentally friendly aggregate collection plans that do not affect the natural ecosystem are mandatory. To address the issues of natural aggregate shortage and treating circulating fluidized bed boiler fl y ash (CFBA), an artificial aggregate was manufactured by using CFBA with BFS and MT added AA, as a possible replacement for natural aggregate. The optimum artificial aggregate mix had a specific gravity of 2.47 and a water absorption rate of 4.05% after aging for 28 days. Over time, the number of gel pores in the artificial aggregate increases, and the porosity decreases. In other words, C–S–H formation in CFBA causes the size of the large pores that appear in the initial hydration to decline, attributed to the continuously generated C–S–H, and hence the number of gel pores increases, leading to a decrease in the porosity. XRD measurement of the artificial aggregate confirmed the presence of calcium silicate (C–S–H), calcium aluminosilicate (C–S–A–H), Al2O3–Fe2O3–mono, and calcium hydride. Comparing the compressive strength of ISO standard aggregate mortar and manufactured artificial aggregate mortar, the initial compressive strength of CFBA was ~ 80% of that of the standard aggregates; however, the compressive strength of CFBA increased with aging. As a result of synthesizing an artificial aggregate using self-hydric FA, it is possible to use some substitution of natural aggregate. |
| Key words:
CFBA · Artificial aggregate · Porosity · Calcium silicate · Gel pore |
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