Generation and stability of bubbles in a cement based slurry

In this article, the fabrication of a single stable cement bubble is investigated. To achieve this goal, the stability of model particle covered bubbles is firstly experimentally studied, by bubbling in a pool filled with micrometric silica particles. Bubble stability is shown to be governed mainly by particle covering rate, which is maximized when particle wetting angle prior to liquid approaches π/2. This angle can be adjusted in situ by electrostatic adsorption of cationic surfactant on silica if proper amount of surfactant is added in the silica suspension. The covering rate is also shown to be governed by the time spent by the bubble in the pool, allowing us to define a timescale for particle adsorption at the liquid/gas interface. In the end, this method is shown to be successful with other types of foamed granular materials such as cement, and the fabrication of a stable and fully covered solid cement bubble is for the first time demonstrated.