UTILIZATION OF ZEOLITE-RICH TUFF FOR THE MANUFACTURE OF BUILDING-MATERIALS BASED ON CALCIUM SILICATE AND TRISULPHOALUMINATE HYDRATES

Hydration of the system tuff-lime-gypsum with and without small additi on of Portland cement has been studied in the range 25-85 degrees C an d up to 28 days curing. The simultaneous formation of calcium silicate and trisulphoaluminate hydrates makes cured products suitable for man ufacturing pre-formed building elements, provided that curing temperat ure is at least 40 degrees C. Portland cement acts as a true catalyst as its addition enhances the formation of both the hydration products. Among other sources of reactive silica and alumina, such as granulate d blast furnace slag and coal fly ash, tuff has proved to be the most reactive material. The process studied in this paper offers an opportu nity for optimally employing tuff by recycling quarry dust. (C) 1997 E lsevier Science B.V.