The results of the research in the field of microwave energy application in the process of manufacturing foam glass gravel from colored glass waste, calcium carbonate as a foaming agent, borax as a fluxing agent and sodium silicate solution as a binder are presented in the paper. The thermal process of sintering/ foaming the powder mixture was carried out in a 0.8 kW-domestic microwave oven adapted for high temperature operation. The foamed product at 845 ºC, with 1.5% calcium carbonate, 7% borax and 8% sodium silicate, reached the highest value of compressive strength (9.5 MPa), thermal conductivity 0.105 W/ m·k, apparent density 0.80 g/ cm3 and a homogeneous distribution of pores in the material structure with dimensions below 1 mm.