Lightweight aggregates are used to make lightweight concrete.
Lightweight aggregates can be processed natural materials (for example expanded clay or expanded shale), processed by-products (for example foamed slag or sintered pulverized fuel ash) or unprocessed materials (for example pumice).
The strength of a lightweight aggregate is directly related to its particle density, since the percentage of voids in an aggregate particle largely determines its strength. An aggregate’s relative density should be less than 2 to qualify as ‘lightweight’ and it should be at least 1.2 for the aggregate to be suitable for use in structural lightweight concrete. The strength is also related to modulus of deformation (Ecd) of the aggregate particles, which may be measured ultrasonically.
Lightweight aggregates may be specified by means of the Laboratory Measurements Dialog.