This article presents the research of dependencies with a filler in the form of fly ash, the mixture temperature and other factors influencing the kinetic characteristics of composite foaming based on the mixture of thermosetting resin (phenol-formaldehyde resins of different brands), fly ash and special modifiers. The article shows the duration and multiplicity of foaming, as well as the induction period of the composition depending on the amount of the filler used and other process parameters. It was found out that to obtain a homogeneous composite, the minimum thickness of the upper layer in the wooden form (S = 1m2 ) should be not less than 4 mm. The reaction with fly ash Thermal Power Station-9 (Open jointstock company “Irkutskenergo”, Angarsk) starts by 27% earlier than the use of fly ash in Ust-Ilimsk Hydroelectric Power Station. Using the obtained data, we developed mathematical models, expressed by regression equations.