A clean dry glass powder useful as a substitute for Portland cement in concrete, in paints, and for other known uses for glass powder produced conventionally can be produced from unsorted post-consumer waste glass, including a subsatantial fraction of non-glass items, by employing glass pulverizing equipment to reduce waste glass to small fragments, allowing removal of trash, employing a multistep washing process to clean the glass fragments, in the preferred embodiment using aggregate cleaning equipment, drying the fragments, preferably using fluidized bed techniques, and grinding the glass to a desired particle size, preferably using a ball mill, in combination with an air classification step to produce a glass powder of uniform particle size.