… of a kind commonly used for concrete aggregates, for road metalling or for railway or other ballast, shingle and …
Explanatory notes
… of a kind commonly used for concrete aggregates, for road metalling or for railway or other ballast, shingle and … of broken pieces of stone which are used for the same purposes, either as such or after crushing, also fall … Round modules of flint are used in ball mills for crushing lime, cement, etc. Flint is, however, mainly used, after …