What types of aggregates are typically used in lightweight concrete?

Lightweight concrete is designed to reduce the overall weight of the concrete mixture while maintaining adequate strength. To achieve this, lightweight aggregates are typically utilized. These aggregates have lower specific gravities compared to traditional aggregates, allowing for a reduction in weight without significantly compromising structural integrity.

Common types of lightweight aggregates include expanded clay, expanded shale, pumice, and other synthetic aggregates. These materials create air pockets within the concrete, leading to a lower density and improved thermal insulation properties. This can be beneficial in various construction applications where weight reduction is essential, such as precast concrete elements and structural components.

Using heavy aggregates would actually increase the concrete's density, which goes against the primary purpose of creating lightweight concrete. Similarly, natural aggregates or aggregates exclusively under 1 mm do not necessarily contribute to the lightweight characteristics intended for this type of concrete. Thus, the choice of lightweight aggregates is key to formulating effective lightweight concrete mixtures.