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 °C~25 °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 °C. Chemical structural data are obtained by nuclear magnetic resonance (NMR) spectroscopy for 6-coordinated (octahedral) aluminum can be observed at low temperature (<0 °C) and the gel contains primarily Q1(1Al), Q2(1Al) and Q3 at 0 °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 °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.