POLYMERIZATION OF ALKALINE-CALCIUM-SILICATE HYDRATES OBTAINED BY INTERACTION BETWEEN ALKALI-SILICA SOLUTIONS AND CALCIUM COMPOUNDS - A SI-29 NUCLEAR-MAGNETIC-RESONANCE STUDY

Alkali-silica solutions containing varying amounts of silica and alkal i ions have been prepared. Solids were obtained by interaction of thes e solutions with calcium hydroxide, calcium chloride or calcium sulpha te. A Si-29 nuclear magnetic resonance study has been carried out on t hese products during the initial and final stages of the synthesis. Th ree major kinds of solids appear in the CaO-Na2O(K2O)-SiO2 phase diagr am; a chain-like nanocrystalline solid, a plate-like amorphous solid, and a three-dimensional amorphous network solid. A relationship betwee n the initial system (i.e., the initial solution) and the final system (i.e., the solid plus the residual solution) is established. The soli d is found to have a higher degree of polymerization than the initial solution while the residual solution is mearly an alkali-silica soluti on without calcium ions.