Influence of slurry characteristics on the bubble stability in foamed concrete

Foamed concrete is a porous material widely used in construction, but its production remains challenging due to bubble stability issues. To address these problems, this study analyzed the influence of bubble characteristics and paste viscosity on bubble stability in foamed concrete, specifically examining pore diameter distribution, collapse depth, and density deviation. Results showed that increasing the strength of the bubble film led to a decrease in the collapse depth of foamed concrete, along with a more uniform distribution of pores and a smaller average pore diameter, indicating improved bubble stability. Adequate viscosity in the cement paste was crucial for limiting the collapse and decreasing density deviation of foamed concrete, as well as ensuring a uniform distribution of early strains. Furthermore, the bubble duration remained unruptured for longer than the setting time of foamed concrete, which was necessary for bubbles to stay stable. A theoretical model of paste viscosity and bubble film strength, based on force analysis of bubbles in foamed concrete, was developed and can predict the required paste viscosity for bubble stability. This study provides important insights into the production of stable foamed concrete and offers a theoretical basis for future research in this area.