Neutralization process packed with fine recycled-concrete aggregates (RCAs) in alkali-producing reactor was tested to verify the treatability of AMD (Acid Mine Drainage) in terms of acid neutralization potential, sludge production, and removal efficiency of heavy metals and SS. As a result, alkaline water produced from the side-stream reactor packed with RCAs was efficient to neutralize AMD to meet effluent pH range of 6-8, and to remove heavy metals and SS. Direct contacting of RCAs to AMD main-stream was not proper because of precipitation of metal-hydroxides on the surface of RCAs, and handling problem of used RCA with metal component contamination.