Strength characteristics of lime-activated slag cement

This paper reports on the strength and hydration products of slag cement prepared by activating ground granulated blast-furnace slag with lime and plaster of Paris (PoP). The compressive strengths of slag–lime–PoP mixes at specified curing periods were determined by varying the lime content from 5% to 40% and PoP from 1% to 10% of the dry weight of slag. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and differential scanning calorimetry tests were performed to examine the hydration products, the rate of hydration and the microstructure. A correlation was established between the developed strength, raw material compositions and the microstructure. Optimisation of raw material compositions in the mix was determined by adopting the generalised reduced gradient algorithm and it was found that the optimum composition of raw material changed marginally with the curing period of mortar specimens.