A batch of coal fly-ash, soda and lime was melted, quenched to a glass and then devitrified, by one-step heating cycles, forming coarse fibrous microstructures with pores and cracks, resulting in low strength materials. The crystallization behaviour of the based glass was further studied by adding a nucleating agent, TiO(2). The resulting structural and microstrutural changes were investigated by differential thermal analysis, scanning electron microscopy, x-ray diffraction, dilatometry and density measurements. The results indicated that the addition of TiO(2) could provide a finer grained microstructure, suitable for the production of structural materials.