Patent ID: 7413602

Claim:
A process for the production of concrete, comprising as a pozzolanic constituent a proportion of glass powder produced by processing a stream of post-consumer waste glass containing items of non-frangible materials, comprising the following steps, performed in the sequence given: producing a dry glass powder comprising particles of which at least a major fraction are of size 325 mesh or finer, and containing no more than about 2% moisture, by: pulverizing the stream of post-consumer waste glass containing non-frangible constituents such that glass in said stream is reduced to fragments of average maximum size ⅛ inch or less; while non-frangible items are not reduced to said size, and performing a size-based separation of said reduced glass fragments from said non-frangible items; washing said reduced glass fragments, to separate plastic and paper fragments therefrom, and to remove organic contaminants therefrom; drying the washed glass fragments to a moisture content of no more than about 2% by weight; and grinding the dried glass fragments into a powder, using a ball mill and a size-based classifier in a continuous ball milling and size-based classification process, wherein the glass fragments having been ground into particles are withdrawn from said ball mill and conveyed to said size-based classifier, with particles over a maximum average particle size being returned to said ball mill for further grinding, and the remainder being separated so as to form a powder, such that at least about 60% of the particles of said powder are of no more than 325 mesh particle size; and mixing said glass powder with a larger quantity of Portland cement, aggregate materials, and water, said glass powder serving as a pozzolan, to form concrete.