The effect of curing temperature on basic geopolymeric reactivity and hardening behaviour of blast furnace slag were investigated using the mixture of pulverized slag and several alkaline solutions of relatively high concentration. For the pastes prepared at several different temperatures between 20 o C and 90 o C, setting time and heat of reaction were examined while mineralogical and morphological examinations were performed for the hardened paste after curing period at same temperature. The geopolymeric reaction of slag was revealed to be accelerated strongly according to the curing temperature regardless of the sort and concentration of the alkaline solution. The increase of concentration of the alkaline solution within 9 M and the existence of silicic ion in the solution also promoted the reaction severely. The mineral component and their ratio of the hardened paste were revealed to be influenced by the chemical species and silicic ion contained in alkaline solution rather than by the curing temperature. The higher temperature and longer period of curing stage were effective for the sustained formation of geopolymer and succeed improvement of density and uniformity of morphology of the final hardened body.

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For the lower-temperature preparation of calcium monoaluminate(CA, C:CaO, A:Al 2 O 3 ) clinker which is hard to synthesize purely within its melting point, an equimolar hydrate was obtained and then used as a starting raw material of clinker burning. The hydrate was prepared from a mixture of waste oyster shell and industrial aluminium hydroxide by heating to 1200 o C, grinding and mixing with water. The hydrate was composed of amorphous aluminium hydroxide and C 3 AH 6 (H:H 2 O) formed by resolution-precipitation mechanism of the system C-A-H. By heating the hydrate, nearly pure and porous calcium monoaluminate clinker was formed at 1400 o C which is fairly lower temperature than that of its melting point. The formation of calcium monoaluminate was performed mainly by the reaction between amorphous alumina and C 12 A 7 caused by the decomposition of C 3 AH 6 . The immediate and earlier formation of C 12 A 7 seemed to be accelerated by not only high surface area and instability of the thermally decomposed hydrate but also the catalytic effect of water decomposed from the hydrate. The final calcium monoaluminate clinker was very porous because of the influence of highly porous shape of the thermally decomposed hydrate.

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