Bituminous composn filler - heat treated paleozoic silico-argilaceous limestone

摘要

The filler comprises a finely-ground material principally consisting of a paleozoic silico-argilaceous limestone which has been preground and treated at 500-1000 degrees C. The material may consist entirely of the above material or a mixture thereof with other finely-ground minerals, e.g. limestone, porphyry, schist, slag, or fly-ash, or a mixture of finely-divided materials prepd. by thermal treatment of clay or schist, pure or as a mixture.