Preparation and properties of geopolymer from blast furnace slag

In this paper, blast furnace slag was investigated as a source of the basic Si–Al ingredient of geopolymer. On the basis of compressive strength, the effects of grinding time on the activity of blast furnace slag and the effects of activator types, compound activator and particle size of blast furnace slag on the compressive strength were studied. The results showed that the optimum parameters were as follows: the grinding time was 12 hours, the granularity of blast furnace slag powders was 0·053–0·075 mm, the incorporation of blast furnace slag was 90 wt-%, the mass ratio of water glass/NaOH was 7:3, the liquid-to-solid mass ratio was 0·25, Additionally, X-ray diffraction, infrared spectroscopy and scanning electron microscope with energy dispersive spectrometer analysis were used to analyse the composition and polymerisation mechanism of the geopolymer. The reaction products of slag-based geopolymer paste was composed of two separate amorphous phases (geopolymeric and CSH gel).