Effect of Surface Tension, Foaming Stabilizer, and Graphene Oxide on the Properties of Foamed Paste

Foamed paste has attracted much attention because of its excellent thermal insulation performance and diverse applications in infrastructure projects. However, there are still some shortcomings hindering the further application of foamed paste, such as the low mechanical strength and the lack of effective methods to evaluate the properties of foaming bubbles. In this study, surface tension was used as the key parameter to characterize the properties of bubbles. A novel nanomaterial, graphene oxide was employed to enhance the mechanical strength of foamed paste, which was also effective in decreasing the surface tension of aqueous solution. A central composite design scheme was employed to evaluate the influence of three selected factors, surface tension, Sodium Phosphate/foaming reagents mass ratio, and graphene oxide/binder mass ratio, on the engineering properties of foamed paste. Additionally, mercury intrusion porosimetry and scanning electron microscope were employed to elucidate the structure of pores, X-ray diffraction and thermogravimetric analysis were employed to further analyze the hydration products at the microscopic scale. This study reveals that surface tension holds great potential in predicting the engineering properties or performances of foamed paste, and a new mechanism may be developed for explaining the influence of graphene oxide on the pore structure of cementitious materials by evaluating the surface tension of pore solution.