We prepared foam glasses from cathode-ray-tube panel glass and CaCO3 as a foaming agent.We investigated the influences of powder preparation, CaCO3 concentration and foaming temperature and time on the density, porosity and homogeneity of the foam glasses.The results show that the decomposition kinetics of CaCO3 has a strong influence on the foaming process.The decomposition temperature can be modified by varying the milling time of the glass-CaCO3 mixture and thus for a specific CaCO3 concentration an optimum milling time exists, at which a minimum in density and a homogeneous closed porosity are obtained.Under the optimum preparation conditions the samples exhibit a density of 260 kg/m3.The thermal conductivity of the foam glass was measured to be 50-53 mW/(m K).The observed dependence of the foaming process on the decomposition kinetics of the foaming agent can be applied as a universal rule for foaming processes based on thermal decomposition.