Described is a building material composition prepared from or having added thereto a particulate material selected from particulate polysaccharides or particulate polysaccharide derivatives. The particulate material of the building material composition is prepared by a method comprising: (a) forming a feed composition comprising a member selected from the group consisting of polysaccharides and polysaccharide derivatives, and 35 wt. % to 99 wt. % of water, based on the total weight of the feed composition, wherein said member is at least one of swelled and dissolved in the feed composition; (b) contacting, in a mill, the feed composition with a gas stream, thereby converting simultaneously the water of said feed composition into water vapor, and said member of said feed composition into a solid state form of finely particulate material; (c) separating the particulate material from the gas stream; and (d) optionally drying the particulate material. Examples of building material compositions according to the present invention include tile adhesives and joint fillers.