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Title |
Infrared Transmitted-Light Sensor Response to Fine Aggregate Fines
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Authors |
장지성(Jisung Jang) ; 안예린(Yerin An) ; 유은지(Eunji Yu) ; 김민형(Minhyeong Kim) ; 박세언(Se-Eon Park) ; 이방연(Bang Yeon Lee) |
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DOI |
https://doi.org/10.11112/jksmi.2026.30.5.57 |
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Keywords |
잔골재; 미립분; 광물; 적외선 투과광 센서; 광학밀도 Fine aggregate; Fines content; Mineral type; Infrared transmitted-light sensor; Optical density |
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Abstract |
Material finer than 0.08 mm in fine aggregate affects the workability and strength development of concrete. The standard washing test requires two oven-drying stages to constant mass before and after washing and typically takes about 48 h, so it is impractical at the point of aggregate delivery. The purpose of this study is to evaluate the effects of the mineral type of fines and the coexistence of fine aggregate on the output voltage of an infrared transmitted-light sensor and, on this basis, to derive an empirical relationship for the fines content of fine aggregate. Kaolin, bentonite, and calcium carbonate were selected to represent non-swelling clay, swelling clay, and crushed rock powder. Suspensions containing 1 g to 10 g of fines per 100 g of washed fine aggregate were prepared with and without fine aggregate, and each condition was measured five times. The response to aggregate addition was opposite depending on the mineral: the output voltage decreased for kaolin but increased for bentonite. At the 1 g condition with fine aggregate, the relative contributions to the apparent optical density were 45.9 % for kaolin, 44.6 % for calcium carbonate, and 9.5 % for bentonite. Rescaling the coefficient of the power-law relationship derived from the mixed-fines data by a factor of 3.11 with four unwashed natural sand samples yielded residuals of ?0.66 % to +0.71 % over a fines content range of 4.4 % to 5.0 %.
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