Abstract: A method for the preparation of aggregates (as herein defined) comprising the following steps: 1. providing core materials selected from the group consisting of particulate and granular material in a predetermined size range; 2. admixing said core materials with a coating composition comprising a. a film forming agent (about 10%-20% by weight). b. a gluing agent (5%-10% by weight) and c. a volatile solvent (70%-90% by weight) in which both, the film forming agent and the gluing agent are soluable, and removing thereafter substantially all of said solvent from the mixture of core materials and coating composition, thereby to deposit on said core materials an adherent first coat being at least 1% of the aggregate; 3.