Group I moderate lightweight concrete uses what type of aggregates?

Group I moderate lightweight concrete is specifically designed to provide a lower density while still maintaining sufficient strength for various construction applications. The key to achieving this lightweight nature lies in the use of expanded aggregates.

Expanded aggregates are made from materials that have been processed to create a porous structure. These materials, such as expanded clay, shale, or slate, have a significantly lower density compared to traditional aggregates. When incorporated into concrete, these expanded aggregates reduce the overall weight of the mixture while also offering good thermal and acoustic insulation properties. Additionally, they help to improve the workability of the concrete mix.

Natural sand, coarse aggregates, and granite gravel, while all commonly used in concrete applications, do not provide the lightweight characteristics that are essential for Group I moderate lightweight concrete. These traditional materials tend to have higher densities, which contradicts the objective of creating a lightweight concrete mix. Thus, the correct answer highlights the unique characteristic of expanded aggregates in lightweight concrete production.