The dehydration behavior of VM-Raw was determined by the thermogravimetric analysis (TGA, Q5000) method. This TGA test was carried out over a temperature range from 25 C to 1000 C, at a heat ramping rate of 10 K/min under nitrogen gas atmosphere. The mineralogical compositions of VM-Raw and the thermally expanded ones were examined by X-ray diffractometer (X’pert Pro, PANalytical). Their specific surface areas were measured by the Brunauer–Emmett–Teller method (BET, Coulter SA3100). Furthermore, the micro-morphologies of VM-Raw and EVM-800 were characterized by scanning electron microscopy (SEM) instrument (JEOL-6390).