The compression and strength characteristics of soils were examined in relation to the presence of isolated solid inclusions. Investigations were carried out on samples of kaolin with solid inclusions of angular crushed basalt and steel ball bearings (to represent rounded particles). The presence of solid inclusions was found to have a significant effect on the compression and strength characteristics of these composite soils and it is postulated that this behaviour is related to the formation of strong arches between the individual solid inclusions. This phenomenon was found to be subdued when the surface of the solid inclusion was smooth, suggesting that particle shape also has a considerable influence on the mechanical behaviour of composite materials.
Sivakumar, V., Donohue, S., Rødvand, L., Nanda, S., & Tripathy, S. (2018). Behaviour of normally consolidated clay containing isolated solid inclusions. Proceedings of the ICE - Geotechnical Engineering, 171(4), 345-356. https://doi.org/10.1680/jgeen.17.00131