Four types of blast furnace slag-based geopolymers from prodn. of crude iron and optionally modified with (i) alkalies (KOH or NaOH) or (ii) with the alkalies and Al dust were prepd. and then studied for their suitability as potential building materials. Bending and compression strength and thermal conduction coeff. were used as criteria for the suitability of geopolymers. The detd. values of the parameters were compared with the corresponding values in the stds. Geopolymer obtained by (ii) method was recommended as a housing material for floor heating of rooms.