The specific structural groups present in the 20Li20-80Si02 wt% base glass compositions with the addition of gradually increased percent of blast furnace slag, all samples and their corresponding glass ceramics were investigated by means of infrared spectroscopy. The density of the glass and heat treated glass ceramics were also measured. The effect of addition of slag to glass and glass ceramics in its mechanical properties such as microhardness was measured. The crystalline phases found in the glass ceramics were defined with the aid of an x-ray diffractometer. Leaching behaviour was also studied. The results showed an improvement in the glass properties with the addition of the slag. However, there was deterioration in the glass ceramic properties especially in its durability in acidic solution. This was discussed on the basis of phase separation.
