Lightweight aggregates are materials used in construction that have a lower density than traditional aggregates like sand and gravel. They are often made from natural materials, such as expanded clay, shale, or pumice, or from synthetic materials like expanded polystyrene. These aggregates help reduce the overall weight of concrete, making it easier to handle and transport. The use of lightweight aggregates can improve the thermal insulation properties of concrete structures, leading to energy savings. Additionally, they can enhance the durability and workability of concrete, making it suitable for various applications, including precast concrete and lightweight concrete blocks.