Recycled cenosphere, which is a hollow shaped particle from fly ash, has become attractive as a building material due to its light weight and excellent heat insulation and soundproof properties. In this paper, we investigated the effect of cenosphere size on the physical and optical properties. High brightness of cenosphere as raw material is required for a wide range of ceramics applications, particularly in fields of building materials and industrial ceramic tiles. Cenospheres were sorted by particle size; the microstructure was analyzed according to the cenosphere size distribution. Cenospheres were generally composed of quartz, mullite, and amorphous phase. Colour measurement corresponding to chemical composition revealed that the contents of iron oxide and carbon in the cenospheres were the major factors determining the brightness of the cenospheres.

• 이원준(한국세라믹기술원 이천분원) | Won-Jun Lee (Icheon Branch, Korea Institute of Ceramic Engineering & Technology(KICET), Icheon 17303, Republic of Korea)
• 황해진(인하대학교 신소재공학부) | Hae-Jin Hwang (School of Material Science and Engineering, Inha University, Incheon 22212, Republic of Korea)
• 한규성(한국세라믹기술원 이천분원) | Kyu-Sung Han (Icheon Branch, Korea Institute of Ceramic Engineering & Technology(KICET), Icheon 17303, Republic of Korea)
• 황광택(한국세라믹기술원 이천분원) | Kwang-Taek Hwnag (Icheon Branch, Korea Institute of Ceramic Engineering & Technology(KICET), Icheon 17303, Republic of Korea)
• 조우석(한국세라믹기술원 이천분원) | Woo-Suk Cho (Icheon Branch, Korea Institute of Ceramic Engineering & Technology(KICET), Icheon 17303, Republic of Korea)
• 김진호(한국세라믹기술원 이천분원) | Jin-Ho Kim (Icheon Branch, Korea Institute of Ceramic Engineering & Technology(KICET), Icheon 17303, Republic of Korea) Corresponding author