The document discusses the recycling of concrete waste. It begins by introducing concrete as the world's second most consumed material and its importance for urban development. Issues with construction and demolition waste like lack of landfill space are also mentioned. The rest of the document discusses in detail recycling of concrete aggregates through various methods. Two case studies on experimental studies of recycled aggregates in high strength concrete and their effect on compressive strength of different grades of concrete are also presented. The conclusions indicate that recycled aggregates can be used as substitutes for natural aggregates, especially at lower replacement levels, helping reduce waste and save space in landfills.