What type of aggregate is commonly used in lightweight concrete mixes?

Expanded clay is commonly used in lightweight concrete mixes because it has a lower density compared to traditional aggregates like granite, basalt, and sandstone. The process of expanding clay involves heating it until it is transformed into lightweight, porous particles, which reduces the overall weight of the concrete while still providing adequate strength and insulation. This characteristic makes lightweight concrete ideal for applications where weight is a crucial factor, such as in structural elements designed for minimizing load on buildings or other constructions.

In contrast, granite, basalt, and sandstone are all denser natural aggregates that would increase the weight of the concrete mix and are typically used in standard or heavy-duty concrete applications.