The document discusses using recycled aggregates in concrete to improve sustainability. It studies the compressive strength of concrete made with various combinations of recycled and natural aggregates. Recycled aggregates are produced from construction and demolition waste through crushing. Using recycled aggregates can help reduce the depletion of natural resources and cut down on waste sent to landfills. The document tests the compressive strength of different concrete mixes containing recycled aggregates to determine their suitability for construction applications.