Waste concrete fine powder that is residue after aggregates recycling of demolished concrete is disposed as a low material of value. We have developed the process of dividing waste concrete fine powder into a material by using acid. In this paper, the process of waste concrete fine powder was applied and the manufacturing process of recycled fine aggregate which does not discharge waste concrete fine powder was developed. And by using ultrasonic for this recycled-fine-aggregate process, it succeeded in the quality of recycled fine aggregate, and improvement in processing efficiency.
