Low temperature depolymerization and polycondensation of a slag-based inorganic polymer

In this paper, the depolymerization and polycondensation process, compressive strength, gel content and conductance of an alkali-activated slag (AAS) (an inorganic polymer or high-calcium geopolymer) paste cured at low temperature (-25 degrees C similar to 25 degrees C) were studied. The results showed that gel content of the AAS inorganic polymer sample first increased and then decreased with the decreasing of the curing temperature for 24 h, reaching a maximum value of 37.8 wt% in the samples cured at 0 degrees C. Chemical structural data are obtained by nuclear magnetic resonance (NMR) spectroscopy for 6-coordinated (octahedral) aluminum can be observed at low temperature (< 0 degrees C) and the gel contains primarily Q(1),(1Al), Q(2)(Al-1) and Q(3) at 0 degrees C. The inductively coupled plasma emission spectrometry (ICP) analysis of the products showed depolymerization of a great amount of slag at low temperature. The impedance analysis indicated that low temperature (< 0 degrees C) will inhibit the polycondensation process but almost not affect the depolymerization process so as to make a distinction between the depolymerization and polycondensation process in the AAS inorganic polymer system.