Quality improvement of recycled fine aggregate using steel ball with the help of acid treatment
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There is a need to promote high-value added utilization of recycled aggregates, considering the aspect of effective use. It should be noted, however, that recycled fine aggregates are generally low in quality due to the presence of cement paste attached to the aggregate surface. Based on this, there have been studies, which aimed to improve the quality of recycled aggregates using mechanical abrasion methods of removing the cement paste based on the principles of crushing, grinding and abrasion and beneficiation method using heat or acid. Accordingly, this study was performed as part of the research to improve the quality of recycled fine aggregates with the aim to effectively remove cement paste using steel ball as mechanical method and acid as chemical method. The results of the experiment showed that the oven-dry density and absorption ratio obtained after the abrasion process using sulfuric acid solution were 2.51 g/cm3 and 2.3%, respectively. This evidenced the quality improvement of the recycled aggregates as they satisfied the quality criteria of over 2.2 g/cm3 and under 5%, respectively, for Class I concrete proposed in the quality standards for recycled aggregates as well as natural sand proposed in Korea Standard criteria of over 2.5 g/cm3 and under 3%.
KeywordsWaste concrete Recycled fine aggregate Acid treatment Cement paste Absorption ratio
This study was supported by the Research Program funded by the Seoul National University of Science and Technology.
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