Construction and validation of a model for asphalt foaming behavior

Asphalt and water produce foamed asphalt through contact collision, turbulent mixing, heat and mass transfer. In this process, the viscosity change of asphalt affects the flow characteristics and heat transfer of the fluid, and the gas content in foamed asphalt is determined by the transformation rate of water from liquid state to gas state. The standard volume of fluid (VOF) model can capture the flow characteristics of phase interfaces and interactions between phases in asphalt foaming behavior but cannot characterize the viscosity changes and water state changes of asphalt. This article introduced the functions of asphalt viscosity change and water state change in the standard VOF model. Furthermore, a control model for asphalt foaming behavior was constructed. This model, the standard VOF model, and the relevant data from the asphalt foaming test were compared. The results show that the numerical simulation results of the two models are consistent with the change trend of the asphalt foaming test results in terms of foaming cavity pressure. The root mean square (RMS) error of pressure values between the standard VOF model and asphalt foaming test results is 2.2%. The RMS error between the asphalt foaming behavior model constructed in this article and the pressure values obtained from asphalt foaming tests is 1.3%. This further validates the accuracy of the asphalt foaming model constructed in this article.