This Section of BS 812 describes a gravimetric method, based on sedimentation, for the determination of the proportion of material finer than 20 µm in particle size in aggregates.
This method is not suitable for particles larger than 20 µm because of their short settling times.
Methods for the determination of particle size distribution of an aggregate down to the passing 75 µm fraction are described in BS 812-103.1. If the proportion of material between 20 µm and 75 µm is required, this may be calculated from the results of the determination carried out in accordance with this Section of the BS 812 series and BS 812-103.1.